`United States Patent
`[191
`Stengel
`
`
`
`US005506493A
`
`I 1111111111111111 11111 111111111111111 111111111111111
`
`
`
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`
`
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`IIIII IIIIII Ill lllll llll
`5,506,493
`[11]Patent Number:
`
`
`
`[45]Date of Patent:Apr. 9, 1996
`
`[54]SWITCHING REGULATOR AND AMPLIFIER
`SYSTEM
`
`5/1988 Van Der Zwart ....................... 330/297
`
`4,742,311
`4,752,747
`
`
`6/1988 Botti et al ............................... 330/297
`5,075,634 12/1991 French .................................... 330/146
`
`[75]Inventor:
`Robert E. Stengel,
`
`Ft. Lauderdale, Fla.
`
`OTHER PUBLICATIONS
`
`Ill.Motorola, [73]Assignee: Inc., Schaumburg,
`
`
`
`
`Motorola Semiconductor-Master Selection Guide 1992
`
`
`
`
`
`
`(Rev 5)-Cover pages, pp. 5.3-7.
`
`[21]Appl. No.: 402,242
`
`[22]Filed:Mar. 10, 1995
`
`Primary Examiner-James B. Mullins
`
`
`
`
`Attorney, Agent, or Firm-Barbara R. Doutre
`
`[57]
`
`ABSTRACT
`
`
`
`
`
`Related U.S. Application Data
`
`a controller A voltage regulator (200) includes (204) which
`
`
`
`
`
`
`
`
`selectively activates a plurality of switching means (208,
`[62] Division of Ser. No. 237,325, May 3, 1994, Pat. No. 5,422,
`
`
`
`
`
`current 210, 214, and 212) in order to select between a first
`
`
`317, which is a continuation of Ser. No. 269,944, Jun. 29,
`
`
`1994, abandoned, which is a continuation of Ser. No.
`
`
`
`
`loop in which an energy storage device is charged by an
`
`974,017, Nov. 10, 1992, abandoned.
`
`
`
`input supply and a second loop in which the energy storage
`6 ......................................................
`
`
`
`
`device is coupled to the output terminal (242) of the regu­
`[51]Int. Cl.
`G0SF 1/613
`
`
`
`
`lator The switching from the second current loop to
`(200).
`
`[52]U.S. Cl ........................... 323/223;
`
`323/224; 323/285;
`
`
`the first is governed by the controller that (204) determining
`
`323/351
`
`
`
`the loop current in the second loop has reached a predeter­
`
`[58]Field of Search ..................................... 323/223, 224,
`
`
`
`
`mined level. A first switching audio amplifier (300) is
`
`323/225, 282, 285, 299, 351
`
`
`
`disclosed which uses the voltage regulator (200) to provide
`
`
`
`
`a continuously variable output voltage (318) in order to
`
`
`
`provide for high quality amplification which is independent
`
`
`of the volume setting. A second audio amplifier
`(400)
`
`
`
`discrete voltage includes a converter (436) which provides
`
`
`
`
`3,531,712 9/1970 Cecchini ................................. 323/224
`
`
`
`levels to a full wave bridge in order to provide improved
`
`
`3,829,788 8/1974 Ford .......................................... 330/10
`audio output.
`
`4/1977 Jasinski et al . .
`4,016,501
`
`
`4,586,002 4/1986 Carver .
`
`
`
`
`
`7 Claims, 5 Drawing Sheets
`
`[56]
`
`
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,717,889 1/1988 Engelmann ............................. 330/297
`
`Iin
`
`--
`
`208
`
`L
`
`242
`
`�!vout
`
`228
`
`Vin
`-\
`206
`
`230
`
`204
`
`GND
`
`i-Vin
`
`2161 RL
`
`C
`
`CONTROL
`..........
`202
`
`200
`
`220
`
`226
`234
`
`IPR2022-00716
`Apple EX1005 Page 1
`
`

`

`U.S. Patent Apr. 9, 1996 Sheet 1 of 5 5,506,493
`
`FIG.1
`
`(PRIOR ART)
`
`Iin --
`
`Vin
`
`S D
`01
`
`,-------
`
`R3
`
`-----�
`
`L Iout
`Vout
`
`---"
`
`--
`
`D
`
`R1
`
`C
`
`-_,JCONTROLLEl-<'I------
`
`R4
`
`100
`
`R2
`GND
`
`FIG.2
`
`Iin
`
`208
`
`L
`
`214 Vin �/Vout
`
`242
`
`----------
`
`Vin
`-'\
`206
`230
`
`204
`
`GND
`
`32 03 -155
`i---Vin
`2161 RL
`C
`
`CONTROL
`202
`
`200
`
`220
`
`226
`234
`
`IPR2022-00716
`Apple EX1005 Page 2
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`

`

`U.S. Patent Apr. 9, 1996 Sheet 2 of 5
`
`5,506,493
`
`FIG3
`
`CONTROL
`342� /316
`306 336
`\ \ IA(t)
`I t
`318
`01"\ EFFICIENT
`/ajA(t)I
`DC TO DC
`CONVERTER
`
`.----- J!---<,_,_____------1
`
`328
`\
`
`A(t)
`1\J
`314
`A(t) /'---e--4
`\
`
`334
`
`-A(t)
`
`304
`
`6
`
`320 340
`302
`L�EL
`.J7...i
`/ SGN(A(t))
`SHIF.TE
`.z-�/----t==:::;::::;:::;.::;:::-t
`---.....-------'
`I
`SGN(A(t)) _......,. __
`332 338
`CONTROL
`
`300
`
`IPR2022-00716
`Apple EX1005 Page 3
`
`

`

`�
`\C
`�
`
`01
`
`01
`
`s,
`�
`
`tit
`
`v:;
`
`� v:;
`�v:;
`
`!:"I
`> "0
`
`"""" �
`�
`�
`•
`•
`
`/
`
`SGN(A(t))
`
`434
`
`.J7...i
`
`406
`
`408
`
`444
`
`402
`I
`A(t)�.
`
`SHIFTER
`LEVEL
`PWM/
`/
`418
`
`DC TO DC
`
`452 MULTILEVEL
`
`436
`
`DISCRETE-ANA CONVERTER
`CONT -ANA I EFFICIENT
`
`438---
`
`440
`
`454
`
`---
`
`BATTERY
`
`CONTROLS
`
`FIG.4
`
`TO
`
`IA(t) I
`IV\
`416
`
`A(t)
`
`---u1JUU1J1f �
`
`/
`450
`
`456 422
`
`432
`
`/
`
`�
`
`CONTROLS
`
`/
`
`448
`
`414
`
`400
`
`SGN(A(t))
`
`7.-1'
`
`410
`
`-A(t)
`J'
`
`442
`
`�
`
`/446
`
`a( I A( t) I)
`
`�
`
`IPR2022-00716
`Apple EX1005 Page 4
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`

`

`U.S. Patent Apr. 9, 1996
`
`Sheet 4 of 5 5,506,493
`
`LO
`
`...... /
`:::i
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`I 1111 Ill
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`
`IPR2022-00716
`Apple EX1005 Page 5
`
`

`

`U.S. Patent Apr. 9, 1996 Sheet 5
`of 5
`
`5,506,493
`
`(.Q
`
`_J
`0
`
`0:::
`0:::
`I-
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`
`IPR2022-00716
`Apple EX1005 Page 6
`
`

`

`1
`SWITCHING REGULATOR AND AMPLIFIER
`SYSTEM
`
`5,506,493
`
`2
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a diagram of a prior art step down switching
`
`voltage regulator.
`
`
`
`This is a divisional of Ser. No. 237,325, filed May 3,
`FIG. 2 is a diagram of a switching voltage regulator in
`
`
`
`
`
`
`1994, now U.S. Pat. No. 5,422,317, issued Aug. 15, 1995, 5
`
`
`accordance with the present invention.
`which is a File Wrapper Continuation of patent application
`
`
`
`
`
`
`FIG. 3 is a diagram of a switching audio amplifier in
`Ser. No. 08/269,944, filed Jun. 29, 1994, now abandoned,
`
`
`accordance with the invention.
`which is a File Wrapper Continuation of patent application
`
`
`
`Ser. No. 07/974,017, filed Nov. 10, 1992, now abandoned.
`
`
`FIG. 4 is a second embodiment of a switching audio
`
`
`
`
`
`
`10 amplifier in accordance with the present invention.
`
`
`
`FIG. 5 is a diagram of a voltage converter for use with the
`
`amplifier of FIG. 4.
`
`
`
`
`
`
`This invention relates generally to switching voltage
`
`present invention.
`
`
`
`regulators and more specifically to an audio amplifier which 15
`
`
`uses a switching voltage regulator.
`
`
`
`TECHNICAL FIELD
`
`with the FIG. 6 is a diagram of a radio in accordance
`
`Background
`
`DETAILED DESCRIPTION OF THE
`
`
`
`PREFERRED EMBODIMENT
`
`Referring now to the drawings, and particularly to FIG. 2,
`
`
`
`20
`
`
`
`As the input and output voltages in a step-down switching
`200
`
`
`
`there is shown a step-down switching voltage regulator
`
`
`
`
`
`voltage regulator get closer in voltage level, the voltage
`200
`
`in accordance with the present invention. Regulator
`
`
`
`
`
`potential across the energy storage inductor of the regulator
`
`
`receives an input voltage at first 228 and second 230 input
`
`
`
`
`
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`decreases, causing the inductor's rate of energy storage to
`
`
`
`voltage terminals. The input voltage can come from a
`
`
`decrease. Referring to FIG. 1, there is shown a prior art
`
`
`
`
`or other commonly 25 standard voltage source such as a battery
`
`
`
`step-down switching voltage regulator 100. Current flows in
`
`
`
`
`used energy source. Regulator 200 utilizes a switching
`
`
`
`
`
`
`regulator 100 from the battery (Vin), through inductor (L)
`
`
`(Q2) 210 means such as an N-channel TMOS® SENSEFET
`
`
`and then to the load components, capacitor (C) and resistor
`
`
`
`as the commutating device. Transistor (Q2) 210 is a power
`
`
`
`(R), when transistor switch (Ql) is "on" (activated). When
`
`
`
`MOSFET having the built-in capability of being able to
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`
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`transistor switch (Ql) is "off" (deactivated), diode (D)
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`
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`30 sense the transistor's drain current by measuring a small
`
`
`
`
`conducts, maintaining a current loop with inductor (L) and
`
`
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`portion of the total transistor drain current. The use of
`
`load (R) until transistor (Ql) is turned "on". Once transistor
`
`
`
`transistor 210 provides for a way of determining when the
`
`
`(Ql) is turned "on", diode (D) is biased "off'' again. The
`
`
`
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`commutating current in the loop comprised of inductor (L),
`
`
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`controller used in voltage regulator 100 controls the duty
`
`
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`load (RJ, transistor (Q3) 214, and transistor 210 goes to
`
`cycle (the rate at which the transistor is turned on and off)
`
`
`
`
`switching to be 35 zero, thereby allowing for the regulator
`
`
`
`of transistor Ql in order to maintain a constant output
`
`
`controlled by the loop current. Transistor 210 also provides
`
`
`
`
`
`voltage to the load The divider circuit formed by
`
`for less voltage drop in the loop than a diode.
`(R).
`
`
`
`resistors Rl and R2 is used to inform the controller the
`
`
`
`
`A signal, preferably in the form of a voltage level, is
`
`
`
`output voltage level, while the divider formed by R3 an R4
`
`
`provided via line 218 from transistor 210 to one of the input
`
`
`
`
`is used to inform the control�er the voltage level of the mput
`
`
`
`204. The voltage signal informs
`40 terminals of controller
`
`voltage source.
`
`
`controller 204 of the amount of current flowing in the
`
`The problems encountered with the prior art voltage
`
`
`
`
`previously mentioned current loop comprising of inductor
`
`regulator shown in FIG. 1 are several, as previously dis­
`
`
`214 and 210. By the time the
`(L), load (RL), and transistors
`
`cussed, the amount of energy storage which is achieved by
`
`
`
`
`
`
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`current in the loop reaches zero, the energy stored in
`inductor (L) is dependent on both the input and output
`
`
`
`
`
`
`(C) or stored in capacitor 45 inductor (L) has been either
`
`
`
`voltages of the regulator. Also, the commutating diode (D)
`
`dissipated by load (RJ. Upon controller 204 determining
`
`
`
`
`
`being a fairly high dissipation device (approximately pro­
`
`
`
`that the current in the loop has reached approximately zero,
`
`
`
`viding for a 0.5 volt voltage drop), takes away much of the
`
`
`transistors 210 and 214 are turned off (switched open) by
`
`circuits efficiency during the time transistor (Ql) is turned
`
`
`
`
`
`controller 204 via lines 222 and 226.
`
`
`
`"off'', especially as Vout gets lower in voltage level and the 50
`Saturated switch 210 provides for a lower voltage drop
`
`
`
`
`
`
`
`
`voltage drop across diode (D) becomes a larger percentage
`
`
`
`
`
`and higher efficiency, especially at low output voltages, as
`
`
`
`
`of the overall voltage drop in the loop. A need thus exists for
`
`
`compared to using a commutating diode as shown in FIG. 1.
`
`a switching voltage regulator which is dependent only on the
`
`
`
`
`
`
`
`A lower voltage drop across the commutating device (tran­
`input voltage level and which can provide for lower output
`
`
`
`
`
`
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`sistor 210), allows for an output voltage which can reach
`voltage levels.
`
`
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`55 below two volts with a DC to DC efficiency of greater than
`
`
`
`In switching audio amplifier systems as the audio volume
`50%.
`
`
`
`
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`setting and the battery supply voltage vary, the efficiency of
`The rate of power stored by inductor (L) in FIG. 2, is
`
`
`
`
`
`
`
`the amplifier also varies. Variable supply speaker loads exist
`
`
`determined by the following relationship:
`
`
`
`in the field of audio amplifiers, however they require a
`
`
`
`transformer to move both terminals of the speaker load 60
`
`
`
`about a ground reference as taught in U.S. Pat. No. 4,445,
`
`
`
`
`095, entitled "Audio Amplifier", by Robert W. Carver. The
`
`
`
`addition of a transformer adds both expense and increases
`where:
`
`
`
`
`the size of the audio amplifier circuit. A need exists for an
`R=total resistance in current loop
`
`
`
`
`
`
`audio amplifier system which provides for substantially
`65
`
`L=inductance in Henries
`
`
`
`
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`constant efficiency over varying voltage and volume settings
`
`
`
`V =voltage potential across the inductor
`
`without the need for the use of a transformer.
`
`V2 _!!!... 2
`p .,(t) = Vi(t) = � (1 - e L )
`
`_d
`
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`

`5,506,493
`
`V2
`Rs�aker = 2P audio
`
`4
`3
`t=time transistor (Q2) is in the "ON" (activated) state.
`
`
`
`commutating loop. With the low voltage drop of the com­
`
`
`
`M) allows for a vari­
`
`For a given value of (L) and (t), the rate of energy storage
`
`
`mutating device 210 (the SENSEFETJ'
`
`
`able output voltage below two volts with a DC to DC
`
`
`
`in inductor (L) can be increased by increasing the potential
`
`across the inductor and decreasing the resistance in the
`
`
`
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`efficiency greater than 50%. By using the voltage regulator
`
`charging loop composed of battery 206, transistors (Ql) 208
`
`
`
`
`
`
`
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`such as operated devices 5 of the present invention, battery
`
`
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`transistors and (Q4) 212, and inductor (L). By switching 210
`
`
`
`
`portable radios can operate for longer periods of time given
`
`and 214 to the "OFF' state (not conducting) and switching
`
`
`
`the improved regulation efficiency provided.
`
`
`when (conducting) transistors 208 and 212 to the "ON" state
`
`
`
`
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`Typically, audio amplifiers employed in battery operated
`
`
`
`it is detennined that the commutating current has reached
`
`
`
`devices are class B bridge load amplifiers. The DC to audio
`
`zero, the potential across inductor (L) is increased to Vin and
`
`
`
`
`
`con­10 sine wave power efficiency of this type of amplifier
`
`
`the resistance in the loop is decreased well below the
`
`
`
`figuration is highest (approximately 78% efficiency) at the
`
`
`resistance of the load (RJ. The result is an increased energy
`
`
`amplifier's highest power output and where the device
`
`
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`storage capacity rate and the capability of using faster
`
`
`
`
`voltage drop is lowest. For a fixed supply voltage, the DC to
`
`
`switching frequencies in regulator
`
`
`
`audio power efficiency is directly related to the audio output
`200.
`
`
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`Transistor disconnects 214 temporarily the load (RL) from
`
`
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`
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`voltage level decreases As the output 15 average voltage level.
`
`
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`the inductor, while transistor 212 places one side of the
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`
`
`
`from the supply voltage, more power is dropped across the
`
`
`inductor (L) to ground. At the same time, the other side of
`
`
`
`devices, with the maximum device dissipation occurring at
`
`
`
`
`the inductor is coupled to the input voltage source (Vin)
`
`
`
`
`0.707 of maximum output voltage level. In addition, distor­
`
`
`
`providing for improved energy storage rate to inductor (L).
`
`
`
`
`tion or audio quality degrades quickly as the output level
`
`
`into By using the architecture storage of FIG. 2, energy
`
`
`
`
`level. 20 approaches the supply voltage
`
`
`
`inductor (L) is dependent only on the input voltage. In
`
`
`To optimize the relationship, the impedance of the speaker
`
`
`
`addition, the switching of voltage regulator 200 is controlled
`
`
`used in conjunction with an audio amplifier is usually
`
`
`by the commutating loop current and not a predetermined
`
`
`chosen by the following relationship:
`
`
`switching rate as in other regulator designs.
`
`
`
`a SENSEFET transistor Transistor 208 is also preferably
`25
`
`
`
`
`or other similar current sensing switch in order to allow for
`
`
`
`(lin) controller the amount of input current 204 to measure
`where:
`
`
`with via line 240. Resistor Rl is used in conjunction
`V=supply voltage, and
`
`
`
`
`
`transistor a voltage 208 to provide level at line 240 which
`
`
`=maximum expected power level
`
`corresponds to the amount of input current. 30
`P aud;
`
`
`
`
`
`
`
`
`audio power level is example, if the expected In a particular a node divider having Resistors R3 and R4 form a voltage
`
`224 which is used by controller 204 via line 232 to deter­
`
`
`
`equal to 500 milliwatts and the supply voltage is equal to six
`
`
`
`mine the approximate Vout voltage of regulator 200 (the
`
`
`
`
`volts, the optimum speaker impedance would equal 36
`
`
`
`amount of voltage drop attributed to transistor 214 is also
`ohms.
`Referring to FIG. 3, there is shown a switching audio
`
`
`
`
`
`taken into account by controller 204). Controller 204 by 35
`
`
`
`
`with the present inven­amplifier system 300 in accordance
`
`
`
`rate that the switching monitoring node 224 can -adjust
`
`
`
`
`the com­between controller the regulator 204 is switching
`
`
`
`the input audio signal tion. Audio amplifier 300 processes
`
`
`mutating loop and the charging loop in order to keep the
`
`
`
`rectified magnitude A(t) 334 and separates it into a full-wave
`
`
`
`
`output voltage at approximately the desired level.
`
`
`I A (t)I 336 and sine (SGN) signals of positive SGN (A(t))
`
`Input audio signal 302 and negative SGN (A (t)) 304 cycles.
`
`
`
`
`for switching the voltage Controller 204 is responsible
`40
`
`regulator from the first ( charging) loop consisting of battery
`
`
`
`
`
`amplifier 334 is received by operational 314, which sepa-
`(L) and the 206, transistors 208 and 212, and inductor
`
`
`
`
`
`rates the signal into positive A(t) and negative -A(t) differ­
`
`
`
`
`
`ential signals. The positive and negative signals are then
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`second (commutating) loop consisting of inductor (L), load
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`(RJ, transistor 214 and transistor 210. By being able to
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`inputted into a pair of comparators 310 and 312. Comparator
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`know exactly when the current in the second loop is approxi-
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`SGN (A(t)) 312 provides the positive cycle signal 302, while
`45
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`regulator mately zero, controller switch 204 can quickly 200
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`cycle the second comparator the negative 310 provides
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`signal SGN (A (t)) 304.
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`back to the first loop. The present invention not only
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`
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`provides for higher efficiencies, but also provides for a
`Both outputs of operational amplifier 314 are sent one
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`
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`voltage regulator which is only dependent on the input
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`
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`each to digital switches 308 and 306 which are under the
`voltage.
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`the 50 control of signals 302 and 304 in order to produce
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`full-wave rectified magnitude signal I A (t)I 336. Ope ra­
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`of Transistor (QS) 216 which is also under the control
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`opera­controller 204 via line 234 is used in battery saving
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`
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`tional amplifier 314, comparators 310 and 312 and switches
`
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`tions whereby when transistor in a non­(QS) is placed
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`the 306 and 308 form a conversion means which converts
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`cycle audio signal into a magnitude signal 336 and positive
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`conducting ("open") state, the charge in capacitor (C) can be
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`
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`maintained for longer periods of time. This is useful for 55
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`
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`Those skilled in the art 302 and negative cycle 304 signals.
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`
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`battery operated devices in periods of time when the voltage
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`will appreciate that the conversion means can be imple-
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`
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`regulator does not have to be operational, the charge in the
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`mented using a number of known hardware configurations.
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`
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`capacitor (C) can be maintained until the voltage regulator
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`Magnitude signal 336 is in tum sent to a DC to DC
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`
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`
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`begins normal operations again. An external control signal
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`
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`in FIG. regulator discussed converter 316 such as the voltage
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`
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`the 60202 can be provided to controller 204 in order to adjust
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`
`
`
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`signal "al Aoutput 2.Converter an adjusted 316 provides
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`(C) is coupled output voltage of regulator 200. A capacitor
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`(t)I" 318. In effect converter 316 acts as a power amplifier
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`
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`tenninals. in parallel to first 242 and second 220 output
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`
`
`
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`having a continuously changing output signal proportional
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`
`
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`The present invention provides for a voltage regulator
`
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`to impedanceto the input signal I A (t)I 336 which is applied
`200
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`having an energy storage method dependent on the input
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`
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`changeload 322 (e.g., a speaker). The amount of voltage
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`
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`voltage of the regulator only. In addition, the voltage regu-65
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`
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`(denoted by the symbol "a" in output signal 318) which
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`
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`byis controlled signal converter to the output 316 provides
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`
`
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`lator provides for a low dissipation commutating device with
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`the switching controlled by the current flowing in the
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`
`
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`an external control signal 342. Control signal 342 can be a
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`0
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`IPR2022-00716
`Apple EX1005 Page 8
`
`

`

`5,506,493
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`5
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`6
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`416
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`426
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`applied to a pulse width modulator and level shifter 418
`
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`signal which is dependent on the volume setting of amplifier
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`
`
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`which provides two corresponding output signals 434 and
`300, etc ..
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`456which are level shifted and pulse width modulated. The
`
`The output signal 318 coming from converter 316 is then
`
`
`amount of pulse width modulation and level shifting pro-
`
`
`applied to a speaker bridge network comprising of power
`
`
`e signal s vided by circuit 418 is dependent on magnitud
`
`switches such as field-effect transistors 324, 326, 328 and
`
`and external control signal 448. PWM/level shifter 418
`
`330and a load such as a speaker 322. The positive SGN
`
`
`includes an input terminal for receiving external control
`
`
`(A(t)) signal 302 and negative SGN (A (t)) signals 304 are
`signals 448 which come from an external device such as the
`
`
`
`in tum applied to a conventional voltage level shifting
`
`control unit of the electronic device the audio amplifier is
`
`
`circuit 320 as known in the art. Level shifting circuit 320
`
`being used in. For example, if audio amplifier 400 is being
`
`
`preferably adjusts the level of signals 302 and 304 between
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`
`used in a radio, the radio's main control unit (e.g., micro­
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`
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`a voltage range having a top rail equaling the magnitude of
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`signal IA (t)I and a bottom rail of negative five volts. The
`
`
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`processor) can provide an adjustment signal 448 to PWM/
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`level shifting voltage range provides "on" and "off' control
`
`
`level shifter circuit 418 in order to adjust the amount of
`
`of transistors 324, 326, 328, and 330 independent of the
`
`
`PWM and/or level shifting provided. External control sig­
`
`
`output signal level 318. Signals 340 and 338 are equivalent
`
`
`nals 448 can also include a supply voltage.
`to 302 and 304 with levels shifted as needed. Level shifter
`
`
`Output signal 434 is provided to the inputs of logic gate
`
`320 can include an optional control terminal for receiving an
`
`
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`(AND gate) 420, while output signal 456 is applied directly
`external control signal 332. Control signal 332 can come
`to logic gate 432. The other input to logic gate 420 is
`
`
`from the control unit (e.g., microprocessor) of the device
`e SGN (A (t)) signal 410, while the second input
`negativ
`amplifier 300 is being used in. For example, in the case
`
`signal to gate 432 is positive SGN (A(t)) signal 408. The
`
`amplifier 300 is being used in a communication device such
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`output signal 422 of gate 420 is coupled to FETs 424 and 426
`
`
`as a radio, the radio's controller can adjust the amount of
`
`
`while output signal 450 oflogic gate 432 is coupled to FETs
`
`
`level shifting provided by circuit 320 by way of control
`
`428 and 430.Signals 422 and 450 determine which of the
`
`
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`signal 332. Output signal 340 of circuit 320 is applied to the
`FETs are activated.
`
`
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`transistor activation terminal on the left side of the bridge
`
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`and signal 338 is applied to the transistor activation terminal
`25 resfs:i�:��;�:�t:��:
`
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`
`on the right side of the bridge.
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`full-wave bridge formed by FETs 424, 428, 426 and 430. As
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`
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`Output signal 318 is used to adjust the bridge network by
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`
`
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`previously discussed when discussing the full-wave bridge
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`
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`changing the supply voltage into the bridge. While the two
`
`in FIG. 3, the input to the field-effect transistors will
`level shifted signals 338 and 340 are used to determine
`
`
`determine which of the transistor pairs 424 and 430 or 428
`
`
`
`which portion of the bridge is activated. During the positiv
`
`and 426 will be conducting at any given point in time. In the
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`
`
`or negative portion of one conduction cycle, either the upper
`
`preferred embodiment, output signals 422 and 450 cause the
`
`
`left 324 and lower right 330 FETs or the upper right 328 and
`
`
`full-wave bridge to cycle between a first current loop in
`the lower left 326 FETs are turned on. Each associated pair
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`which transistor pairs 424 and 430 or 428 and 426 are
`
`
`of FETs conduct on alternate portions of a cycle. This places
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`activated and a second current loop in which transistors
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`the full voltage of signal 318 across the speaker 322 in a
`
`
`35 and 430 are activated (transistors 424 and 428 deactivated).
`varying and alternating manner. Audio amplifier 300 pro­
`The second current loop occurring in the "off' cycle of
`vides for improvements in both dynamic range and audio
`PWM signals 422 and 450. (In the first current loop, output
`
`
`
`distortion without the need of an isolating transformer.
`signal 446 supplies energy to speaker 442 causing energy to
`In FIG. 4, another embodiment of an audio amplifier 400
`
`be stored in the speaker (inductive portion). When the
`
`in accordance with the present invention is shown. Audio
`
`
`full-wave bridge is in the second current loop (loop formed
`amplifier 400 unlike amplifier 300 which continuously
`
`by transistors 426 and 430 and speaker 442), the energy
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`changes the input voltage 318 being sent into the full-wav
`
`
`
`stored in the speaker is dissipated by the resistive portion of
`
`
`bridge, amplifier 400 provides for discrete voltage levels
`
`the speaker. Amplifier 400 can compensate for changes in
`
`
`446 to be sent to the full-wave bridge. The discrete voltage
`
`
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`supply voltage variations (such as via external signal 448)
`
`
`levels are preferably dependent on the magnitude of the
`
`
`by adjusting the duty cycle of PWM output signals 422 and
`input audio signal 402, desired volume setting and supply
`
`
`450. This is accomplished by adjusting PWM/level shifter
`
`voltage level 438.
`
`
`circuit 418 when a change in supply voltage level is
`
`In amplifier 400, as in the amplifier of FIG. 3, an audio
`
`detected. The amount of duty cycle adjustment being a
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`signal 402 is presented to an operational amplifier 444 where
`
`
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`n. function of the amount of supply voltage variatio
`
`
`the signal is split into positive and negative cycles. These
`
`
`
`In a typical pulse-width modulation (PWM) system the
`signals are in tum fed into a network consisting of com­
`PWM Dynamic Range can be determined by the formula:
`parators 404 and 406 as well as switches 412 and 414, to
`
`
`
`
`produce the rectified magnitude signal 416 and positiv
`
`SGN (A(t)) signal 408 and negative SGN (A (t)) signal
`
`
`The magnitude signal 416 and external signals 454 such as 55
`
`the audio amplifier's volume setting and supply voltage
`where,
`'tmax is the maximum duration transistor pairs 424
`
`
`are inputted into a continuous analog to discrete analog
`and 430, or 428 and 426 are on and 'tmin is the minimum time
`
`
`circuit 440 which takes the control signals and converts
`
`
`
`the transistor pairs are on for one switching cycle. The
`them into an output signal 452 whose voltage level depends
`
`
`
`present invention modifies the dynamic range of the ampli­
`on the input signals 416 and 454. Voltage converter circuit
`
`fier to now be determined by the formula:
`436 can be designed to provide a plurality of discrete output
`
`
`
`voltage levels depending on the levels of the input signals
`
`[ �min ]
`
`416 and 452.The discrete output signal 446 is in tum used
`
`
`to shift the supply voltage level provided to the full-wav
`65 where "a" is the ratio of minimum/maximum discrete volt­
`
`
`rectified bridge.
`
`SGN (A(t)) signal 408 and negative
`The positive
`age level provided by converter 436. Since now the formula
`
`SGN (A (t)) signal 410, and the magnitude signal 416 are
`
`is also dependent on variable "a", the dynamic range of the
`
`e
`410.
`
`10
`
`15
`
`20
`
`e
`30
`
`40
`
`e
`
`45
`
`50
`
`438
`
`60
`
`e
`
`'tmin
`20Log--
`
`�-
`
`20 Log a
`�max
`
`IPR2022-00716
`Apple EX1005 Page 9
`
`

`

`5,506,493
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`
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`an energy storage device having first and second termi­
`
`
`
`8
`7
`age DC to DC converter with conversion efficiency much
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`
`
`
`
`
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`amplifier is increased. The use of a voltage regulator for
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`
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`better than those found in linear regulators and an output
`
`
`
`
`converter 436 further provides for improvements in distor­
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`range which can go down close to zero volts. The audio
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`tion by increasing the low level signal resolution with
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`
`
`
`dynamic similar efficiency, amplifier of FIG. 4 achieves
`
`multilevel pulse width modulated digital signals over fixed
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`
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`
`
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`range and distortion performance as that found in amplifier
`level PWM designs. This provides for smoother zero voltage
`
`
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`5
`
`
`
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`300 while using a simplified multiple discrete output level
`crossings from speaker 442 as compared to other audio
`
`
`
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`DC to DC converter and pulse width modulated switching
`
`amplifier systems. In addition, regulator 436 provides iso­
`
`
`
`
`
`
`
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`circuit. The pulse width modulated signals are applied to a
`lation from supply voltage variations, due to other circuit
`
`
`
`
`
`
`
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`bridge network setting up the speaker current and providing
`loads.
`
`
`
`conditions to sustain the current in the speaker
`commutating
`
`
`Audio amplification efficiency in amplifier 400 is made
`
`10
`
`
`
`
`inductance/resistive network during the off portion of the
`
`independent of the volume setting and the battery supply
`
`
`
`
`
`
`PWM signals. The result is the reduction or total elimination
`
`voltage level without having to use a transformer which adds
`
`
`
`
`
`
`of low pass filtering proceeding the speaker load used in
`
`"' additional cost to the design. By providing multilevel volt­
`
`
`
`
`
`present PWM audio amplifier designs.
`
`ages at 446, the PWM signal "on" duration is maintained at
`
`
`
`What is claimed is:
`
`
`
`an equal or greater duration then the "off" duration. This 15
`first and secondhaving 1.A switching voltage regulator
`
`
`
`
`
`
`
`
`keeps the amount of undesired high frequency energy at or
`
`
`
`
`input terminals and first and second output terminals, com­
`
`
`
`below the desired DC component of each PWM signal. The
`prising:
`
`
`
`result is that less low pass filtering is required in the circuit
`
`
`
`
`
`to prevent the high frequency energy dissipation and to
`nals;
`
`
`provide improved efficiency.
`20
`first, second, third and fourth switching means, the first
`
`
`
`
`
`
`In FIG. 5, a voltage converter 500 for use with the
`
`
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`switching means coupled to the first input terminal and
`
`
`amplifier of FIG. 4 is shown (shown in FIG. 4 as converter
`
`
`
`
`to the first terminal of the energy storage device, the
`
`
`
`
`436). Voltage converter 500 provides for a plurality of
`
`
`
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`second switching means coupled to the first terminal of
`
`
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`
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`discrete output voltage levels. In the preferred embodiment,
`
`
`
`
`the energy storage device and the second input termi­
`
`
`
`
`
`converter 500 provides for three discrete voltage levels. The 25
`
`
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`nal, said first and second switching means each having
`
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`first output voltage level is set for two times the input
`
`
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`current sensing capability, the third switching means
`
`
`
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`voltage level, the second voltage level has the same voltage
`
`
`
`coupled to the second terminal of the energy storage
`
`
`level as the input voltage, and the third voltage level is equal
`
`
`
`device and the first output terminal, the fourth switch­
`to half the input voltage.
`
`
`
`ing means coupled to the second terminal of the energy
`
`
`
`Controller 512 controls the operation of FETs Ql-Q7 via 30
`
`
`
`
`
`storage device and the second output terminal; and
`
`
`
`corresponding control lines 526, 514, 516, 518, 520, 522 and
`
`output524.In order to get an output voltage (V our) across
`
`
`
`
`a control means coupled to the first, second, third and
`
`
`
`
`
`fourth switching means for switching between a first
`
`terminals 506 and 508 which is equal to the VIN voltage,
`
`
`state in which the control means selectively activates
`
`
`controller 512 turns "off'' transistors Q3 516 and Q4, and
`
`
`the first and fourth switching means and deactivates the
`the VIN voltage
`
`turns "on" transistor Q5. This in effect places
`35
`
`
`second and third switching means in order to electri-
`
`
`
`at the output terminals 506 and 508 (in FIG. 4, the output is
`
`
`
`
`cally couple the energy storage device to the first and
`
`
`shown as line 446). Controller 512 in order to provide an
`
`
`
`
`second input terminals when the current sensing capa­
`
`Ql,turns transistors output which is twice the VIN voltage
`
`
`
`
`
`
`bility of the second switching means senses a current
`
`
`Q2 and Q7 "on" in order to charge capacitors Cl 502 and C2
`
`
`
`
`reaching a first predetermined level and a second state
`
`
`
`504 in parallel. Once the capacitors are charged, transistors
`40
`
`
`in which the control means deactivates the first and
`
`QI, Q2 and Q7 are turned "off'' and transistors Q3 and Q6
`
`
`
`fourth switching means and activates the second and
`
`are turned "on". Finally, in order to get a V our which is half
`
`
`
`
`third switching means in order to electrically couple the
`the VIN voltage,
`
`transistors Ql and Q6 are turned "on" until
`
`
`
`
`energy storage device to the first and second output
`
`
`
`capacitors 502 and 504 are charged in series, then transistors
`
`
`
`
`terminals when the current sensing capability of the
`
`Ql and Q6 are turned "off'' and transistors Q3, Q4, and Q7 45
`
`
`
`
`first switching means senses a current reaching a sec-
`
`
`
`
`
`are turned "on". The voltage levels provided via output 506
`ond predetermined level.
`
`
`(same as output 446 in FIG. 4) can vary depending on the
`
`
`
`2.A switching voltage regulator as defined in claim 1,
`
`
`
`
`pa