.
`
`United States Patent [191
`Lindoff
`
`llllllllllllllllllllllllllllllllllllllllllIIIIHIIIIlllllllllllllllllllllll
`[11] Patent Number:
`5,179,724
`[45] Date of Patent:
`Jan. 12, 1993
`
`USOO5l79724A
`
`[54] CONSERVING PO‘WER IN HAND HELD
`adggglggl?ggglgsoglé?ggN
`[75] Inventor: Mats E. G. Linda“; Lund’ Sweden
`
`5,001,776 3/1991 Clark ................................. .. 455/343
`FOREIGN PATENT DOCUMENTS
`54-119819 9/1979 Japan ................................. .. 455/343
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`cgll?lications gizleding Inc
`Paramus’ NJ
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`[21] App1.No.: 641,256
`[22] Filed:
`Jan. 15, 1991
`
`5
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`11/217?
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`455/343 76 83 341
`455/342
`250 1 ’251’1 i94 2’
`’ 23; 1 £34 2 ’245 '1,’ 33O/'2’96
`'
`’
`'
`’
`'
`’
`’
`References Cited
`U.S. PATENT DOCUMENTS
`4,435,846 3/1984
`4,631,496 12/1986
`4,631,737 12/1986
`
`1
`[
`56
`
`Weise ................................ .. 455/343
`Borras et a1. .
`Davis et a1. ....................... r. 455/343
`
`Prima Examiner-Reinhard J. Eisenzo f
`W
`P
`Assistant Examiner-Lisa Charoud
`?tzgltey, Agent, or Firm-Burns, Doane, Swecker &
`a is
`
`AB IRA
`7
`5
`.Cr
`[5 1
`In a radio communication system such as a cellular
`telephone system having battery powered mobile sta
`tions which receive radio frequency signals, an ampli
`?er in the receiver of the mobile station is operated in a
`plurality of different modes in order to reduce power
`consumption. The modes of the ampli?er depend upon
`the strength of the incoming signal and whether the
`transmitter is transmitting. The receiver is also periodi
`cally disconnected from the battery in order to further
`reduce power consumption.
`
`7 Claims, 3 Drawing Sheets
`
`@50
`
`16/71/47:’
`105/11’ 574/70! -51
`l
`
`l
`
`TCL EXHIBIT 1085
`Page 1 of 7
`
`

`
`U.S. Patent
`
`Jan. 12, 1993
`
`5,179,724
`
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`
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`TCL EXHIBIT 1085
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`Page 2 of 7
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`TCL EXHIBIT 1085
`Page 2 of 7
`
`
`
`

`
`US. Patent
`
`Jan. 12, 1993
`
`Sheet 2 of 3
`
`5,179,724
`
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`TCL EXHIBIT 1085
`Page 3 of 7
`
`

`
`US. Patent
`
`Jan. 12, 1993
`
`Sheet 3 of 3
`
`' 5,179,724
`
`AWN/47f
`105/11.’ 5747/04’
`
`1
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`
`TCL EXHIBIT 1085
`Page 4 of 7
`
`

`
`CONSERVING POWER IN HAND HELD MOBILE
`TELEPHONES DURING A RECEIVING MODE OF
`OPERATION
`
`FIELD OF THE INVENTION
`The present invention relates generally to mobile
`radio communications systems which include hand held
`telephones. More particularly, the invention relates to a
`method and apparatus for reducing electrical power
`consumption when operating a hand held cellular tele
`phone.
`
`15
`
`20
`
`35
`
`BACKGROUND OF THE INVENTION
`A cellular telephone system is a radio communication
`system in which a plurality of mobile stations operate
`within a cell which is serviced by a base station. There
`are typically a relatively large number of cells and base
`stations in a given service area. The base station in each
`cell is connected to a message switching center which in
`turn is connected to a public telephone system.
`A recent innovation in the ?eld of mobile radio com
`munications is the hand held or “pocket” telephone
`concept. These telephones are extremely light weight,
`battery operated telephones that can be transported by
`an individual. One of the major design constraints for
`“pocket” telephones is the weight of such devices.
`These devices typically include a transceiver unit, a
`rechargeable battery and a whip antenna. The weight of
`the battery is a substantial portion of the total weight of
`the device. The battery must be of suf?cient size to
`power the “pocket” telephone for a useful length of
`time. A relatively heavy battery enables the pocket
`telephone to be powered for a longer period of time, but
`it reduces the transportability of the “pocket” tele
`phone. A lighter battery unit increases the transportabil
`ity of the “pocket” telephone, but it reduces the useful
`operating time of the device between recharges.
`In the ?eld of mobile radio communications, it is well
`known that the electrical power consumption of the
`receiver can be reduced by periodically disconnecting
`the receiver from the battery during predetermined
`time periods. Typically, such battery saving devices
`disconnect the receiver from the battery for a period of
`several milliseconds. The receiver is then reconnected
`to the battery for a period of several milliseconds, and
`the receiver is capable of monitoring a control channel
`or receiving an incoming call. When a telephone call is
`established, the receiver is continuously connected to
`the power supply. After completion of the call, the
`receiver is again alternately connected and discon
`nected from the power supply. During the idle mode or
`the relatively long periods in which no calls are being
`made or received by the mobile station, substantial
`amounts of electrical energy can be conserved by dis
`connecting the receiver from the power supply.
`One of the major components within the receiver of
`60
`a mobile station that consumes substantial amounts of
`electrical energy is the ampli?er. If the amount of
`power consumed by the ampli?er can be reduced, the
`size of the battery can be made even smaller or alterna
`tively the time between recharges can be further in
`creased. Accordingly, there is a need for an improve
`ment in the operation and structure of the ampli?er in
`the receiver of a “pocket” telephone.
`
`65
`
`1
`
`5,179,724
`
`2
`SUMMARY OF THE INVENTION
`The present invention relates to a method of reducing
`electrical power consumption in a' ‘battery operated
`mobile station such as a “pocket” telephone. The bat
`tery operated mobile station includes a transceiver unit
`having a receiver and a transmitter that are responsive
`to frequency synthesizers. The receiver receives a radio
`frequency signal and applies it to an ampli?er which is
`controlled by a processing circuit such as a suitably
`programmed microprocessor. The ampli?er is capable
`of operating in three different modes. In the ?rst mode
`the ampli?er is biased to a relatively high level when
`ever the transmitter is transmitting. In the second mode,
`the ampli?er is biased to a relatively high level when
`the transmitter is turned off, and the receiver is receiv
`ing a relatively weak radio frequency signal. In the third
`mode, the ampli?er is substantially disabled when the
`transmitter is turned off, and the receiver is receiving a
`relatively strong radio frequency signal. The three
`modes of operation for the ampli?er are controlled by
`the microprocessor. The output of the ampli?er is ap
`plied to a mixer which mixes the received radio fre
`quency signal with the output of the frequency synthe
`sizer associated with the receiver. The output of the
`mixer is then applied to an intermediate frequency stage
`and is processed in a conventional manner.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a block diagram which illustrates a mobile
`radio communication apparatus that utilizes the present
`invention;
`FIG. 2 is a simpli?ed schematic diagram of an inte
`grated circuit which includes a portion of the receiver
`illustrated in FIG. 1; and
`FIG. 3 is a flow chart of the software used by the
`microprocessor to control the receiver.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`FIG. 1 illustrates a block diagram of a mobile cellular
`telephone associated with the present invention. Al
`though they are particularly suited for use in portable
`“pocket” telephones, the principles of the present in
`vention are applicable to any type of mobile telephone
`in which reduction of power consumption is desirable.
`The cellular telephone 9 of the present invention in
`cludes a transceiver having a transmitter 10 and a re
`ceiver 20 which are coupled to a common antenna 11. A
`transceiver oscillator 18 is coupled to a transmitter
`frequency synthesizer 12 and a receiver frequency syn
`thesizer 17. The output of the transmitter frequency
`synthesizer 12 is applied to a transmitter power ampli
`?er 13. The output of the transmitter power ampli?er 13
`is ?ltered by a transmitter ?lter 14 and is broadcasted
`through the antenna 11.
`The receiver 20 receives incoming radio frequency
`(RF) signals through the antenna 1 and ?lters the in
`coming signals with a receiver ?lter 15. The ?ltered RF
`signals are applied to a low noise receiver stage 21. The
`receiver 20 is coupled to a power supply 19 and is con-
`trolled by a microprocessor 16. The receiver 20 prefera
`bly includes the ?lter 15, the low noise receiver stage
`21, a second ?lter 22, a mixer 23 and an intermediate
`frequency (IF) stage which is not shown. The ?lter 22
`is a bandpass ?lter, preferably a so-called ceramic ?lter
`well known in the art. Its center frequency is the RF
`frequency and its bandwidth is such that both the fre
`
`TCL EXHIBIT 1085
`Page 5 of 7
`
`

`
`5,179,724
`
`4
`TABLE l-continued '
`
`temperature
`
`3
`qnency RF+2IF and the component RF--2IF are at
`tenuated. Typically, the IF is 45 MHz. Preferably, the
`low noise receiver stage 21 and the mixer 23 are imple
`mented on an integrated circuit.
`Referring now to FIG. 2, a simpli?ed schematic dia
`gram illustrates the portion of the receiver 20 imple
`mented on an integrated circuit. The integrated circuit
`includes the mixer 23 and an ampli?er 24 which is the
`major component in the low noise receiver stage 21.
`The input to the ampli?er 24 is the ?ltered RF signal
`which is designated as Rx. The integrated circuit in
`cludes a ground terminal GND and an input voltage
`terminal V“ which are coupled to the power supply 19.
`An input terminal designated Transmit receives a signal
`indicating that the transmitter 10 is operating. The inte
`grated circuit includes an input terminal L0 which re
`ceives the output signal L0 from the receiver frequency
`synthesizer 17. The ampli?er 24 also includes an input
`terminal for a signal GSembIe which is provided by the
`microprocessor 16. The GSenable input receives “low”
`and “high” control signals. When the GSeMbIe signal is
`“low” the ampli?er has no current supply and is sub
`stantially disabled. When the GSEMMQ is “high” the
`ampli?er is enabled. The low noise receiver stage 21
`also includes the circuitry necessary to match the con
`trol signals such as the Transmit signal and GSenable
`signal to the ampli?er 24.
`The mobile station, as is conventional in the art, mea
`sures an RSSI (Receiver Strength Signal Indicator)
`signal associated with the IF stage. The RSSI signal has
`a voltage which is a function of the voltage of the re
`ceived signal in the antenna. An A/D converter can be
`used to convert the R581 signal to a digital format
`suitable for application to the microprocessor 16. The
`35
`microprocessor can then determine whether the signal
`is relatively weak or strong, and whether the signal is
`strong enough that the ampli?er 24 can be disabled. '
`The output of the ampli?er 24 is an output signal
`designated REM. The signal RPM, is provided at an
`output terminal designated RFa,” and is applied to the
`?lter 22. The ?lter 22 ?lters the signal and applies it as
`a ?ltered input signal RF],I to the mixer 23 at an input
`terminal designated RF,-,,. The mixer 23 mixes the sig
`nals applied at the L0 input terminal and the RF,-,, termi
`nal. The mixer 23 generates an output signal at an out
`put terminal IF that is coupled to the IF stage. The IF
`stage processes the IF signals in a conventional fashion.
`The RF gain stage or ampli?er 24 disposed on the
`integrated circuit illustrated in FIG. 2 preferably con
`forms to the speci?cations listed below in Table 1.
`TABLE 1
`860-970 MHZ
`min, 15 db, but min. —5 db if
`disabled
`— 10 dBm
`+5 dBm
`50 ohm, input return loss < — 10
`dB
`50 ohm, output return loss
`< — 10 dB
`1 dB Input Compression Point — 10 dBm min.
`Gain Flatness Within
`+/—2 dB
`The Frequency
`Third Order Input Intercept
`Point
`Reverse Isolation
`Noise Figure, NF
`Stability
`
`5
`
`15
`
`20
`
`25
`
`45
`
`50
`
`55
`
`Frequency
`Gain
`
`Nominal Input Level
`Maximum Input Level
`Input Impedance
`
`Output Impedance
`
`—4 dB min.
`
`— 15 dB, +5 dB when disabled
`typ. 2.5 dB, max 3.0 dB
`Unconditionally stable (both
`input and output) for all
`frequencies at working
`
`RF frequency
`L0 frequency
`IF frequency
`Conversion gain
`Conversion gain ?atness
`within the frequency band
`Noise ?gure
`Input impedance
`*
`
`The mixer 23 disposed on the integrated circuit illus
`trated in FIG. 2 preferably conforms to the speci?ca
`tions listed below in Table 2.
`TABLE 2
`860-970 MB:
`900-1050 MHz
`40-80 MHz
`7 dB min.
`+/—l dB
`
`7 dB max.
`50 ohm, return loss < — l0
`dB
`
`Output impedance
`(Open collector output)
`LO port impedance
`
`I000 ohm nominally (800
`ohm as an option)
`50 ohm, return loss < — 10
`dB
`0 dBm max.
`LO input power
`—3 dBm min.
`1 dB input compression point
`2nd order input intercept point +14 dBm min.
`3rd order input intercept point +9 dBm min.
`Port isolation:
`LO-RF
`LO-IF
`RF-IF
`
`30 dB min.
`6 dB min.
`0 dB min.
`
`The integrated circuit of FIG. 2 preferably conforms
`to the general speci?cations listed below in Table 3.
`TABLE 3
`
`Nominal supply voltage
`Current consumption, transmit mode
`Current consumption, standby enable mode
`Current consumption, standby disable mode
`Operating temperature
`Storage temperature
`
`4.5-5.0 V
`max 25 mA
`max 10 mA
`max 4 mA
`—30—+ 85 deg C.
`—65~+ 100 deg C.
`
`The low noise receiver stage 21 is designed to have
`suf?cient gain for the requirements of sensitivity ac
`cording to the systems speci?cation. Such systems spec
`i?cations include the NMT, EAMPS, and the ETACS.
`Typically, the requirements for sensitivity are approxi
`mately 113 dBm. The low noise receiver stage 21 is also
`designed to work well in spite of the interfering signal
`appearing at the input of receiver 20 when the transmit
`ter 10 is on. This feature is obtained by having a suf?
`ciently high receiver “compression point”. The “com
`pression point” of an ampli?er is when the output signal
`of the ampli?er deviates from an ideal linear function of
`the input signal by a value such as 1 dBm. Increasing the
`“compression point”, however, means increasing the
`power consumption of the receiver 20. The low noise
`receiver stage 21 and ampli?er 24 are controlled by the
`microprocessor 16 such that there are three different
`modes of operation.
`The ?rst mode is called the transmit mode. If the
`transmitter 10 is sending, it is desireable for the entire
`circuit including the ampli?er 24 to be enabled. As a
`result, the circuit is in a high current consumption
`mode. The biasing of the ampli?er 24 is relatively high
`giving good sensitivity and good suppression of the
`interfering signals from the transmitter 10. During the
`transmit mode, the control signal which is designated
`Transmit is enabled, causing the gain stage or ampli?er
`24 to be enabled.
`In the transmit mode there will be typically an inter
`fering input signal detected by the receiver 20 with a
`
`TCL EXHIBIT 1085
`Page 6 of 7
`
`

`
`20
`
`5,179,724
`5
`frequency of 45 megahertz below the frequency of the
`desired input signal. This interfering signal results from
`the transmitter being on. The interfering signal will
`have a maximum level of +5 dBm. Ideally the circuit
`should provide the same performance for the desired
`input signal independent of the presence of the interfer
`ing signal. This means that the desired signal must not
`be degraded due to the presence of the interfering sig
`nal. To achieve such a result it is necessary to enable the
`ampli?er 24 and to allow a higher current consumption
`for the circuit in the transmit mode.
`The second mode of operation is called the standby
`enable mode. When the transmitter 10 is off and the
`received signal is weak, the ampli?er 24 is enabled by
`the microprocessor 16 in the standby enable mode. The
`standby enable mode occurs only when the transmitter
`is off, and the ampli?er 24 is biased for relatively low
`noise and high gain. This is possible with a low com
`pression point if a relatively poor suppression of the
`interfering signals is accepted.
`The third mode of operation for the receiver 20 is
`preferably called the standby disable mode. This mode
`occurs when the transmitter 10 is off and the receiver 20
`detects a high level input signal. In this mode the ampli
`?er 24 is totally disabled or biased to a relatively low
`level by the microprocessor 16. Since the input signal
`has a high level, the ampli?er 24 can be switched off,
`and the remaining sensitivity is sufficient for detecting
`the digital signal with a relatively low bit error.
`The control of the microprocessor 16 over the re
`ceiver 20 of the mobile station 9 will now be explained
`through the use of the simpli?ed flow chart of FIG. 3.
`The flow chart of FIG. 3 depicts the logic of the soft
`ware necessary to control the receiver 20. The micro
`processor 16 is started at step 30 and performs the step
`31 of activating the mobile station 9. In step 32 the
`microprocessor connects the receiver 20 to a power
`supply 19. When the receiver 20 is connected to the
`power supply 19, incoming signals can be received and
`processed.
`The microprocessor 16 determines in step 33 whether
`the transmitter 10 is on. If the transmitter 10 is on, a
`Transmit signal is sent to the receiver 20, and the ampli
`?er 24 is biased to a relatively high level. If the micro
`processor 16 decides that the transmitter 10 is not on,
`45
`the microprocessor 16 then performs the step 35 of
`determining the strength of the received signal. If the
`received signal is not strong, the microprocessor 16
`generates an instruction 36 in order to bias the ampli?er
`24 to a relatively high level. If the microprocessor 16 in
`step 35 determines that the received signal is relatively
`strong, the microprocessor 16 generates an instruction
`37 to bias the ampli?er 24 to a relatively low level.
`Since the mobile station 9 at this point is not transmit
`ting, the microprocessor 16 periodically generates an
`instruction 38 disconnecting the receiver 20 from the
`power supply 19. By periodically disconnecting the
`receiver 20 from the power supply 19, substantial
`amounts of electrical power can be conserved.
`The microprocessor 16 then determines in step 39
`whether the mobile station 9 is still active. If the mobile
`station 9 is still active, the microprocessor 16 then re
`connects the power supply 19 to the receiver 20 with
`instruction 32. If the mobile station 9 is to be deacti
`vated, then the microprocessor 16 takes the necessary
`actions to deactivate the mobile station 9. The deactiva
`tion of the mobile station is indicated by step 40 which
`signi?es the end of operation.
`
`6
`While the invention has been described in its pre
`ferred embodiments, it is to be understood that the
`words that have been used are words of description
`rather than of limitation and the changes within the
`purview of the appended claims may be made without
`departing from the true scope and spirit of the invention
`in its broader aspects.
`I claim:
`1. In a radio communication apparatus having receiv
`ing means and transmitting means, that are responsive
`to frequency synthesizing means, coupled to a power
`supply, and controlled by processing means to conserve
`electrical energy, said receiving means comprises:
`means for sensing the strength of a received radio
`frequency signal;
`means for amplifying the radio frequency signal, said
`amplifying means being responsive to the process
`ing means and having three modes;
`in the ?rst mode the amplifying means is biased to a
`relatively high level when the transmitting means is
`transmitting,
`in the second mode the amplifying means is biased to
`a relatively high level when the transmitting means
`is turned off and the radio frequency signal sensed
`by said sensing means is a relatively weak signal,
`and
`in the third mode the amplifying means is substan
`tially disabled when the transmitting means is off
`and the radio frequency signal sensed by said sens
`ing means is a relatively strong signal; and
`means for mixing an output of the frequency synthe
`sizing means with the radio frequency signal in
`order to provide an input to an intermediate fre
`quency stage.
`'
`2. An apparatus according to claim 1 wherein said
`amplifying means and said mixing means are disposed
`upon an integrated circuit.
`3. An apparatus according to claim 1 wherein said
`processing means includes a programmed microproces
`sor that periodically disconnects the power supply from
`said receiving means and controls the modes of said
`amplifying means.
`4. An apparatus according to claim 1 wherein said
`power supply is a battery.
`5. An apparatus according to claim 1 wherein the
`amplifying means includes a compression point which is
`set to a level sufficient to meet sensitivity requirements
`of the receiving means.
`6. A method of conserving the consumption of elec
`trical energy in a transceiver having a receiving portion
`and a transmitting portion by controlling an amplifying
`means of the receiving portion, comprising the steps of:
`sensing the strength of a received signal;
`biasing the amplifying means to a relatively high
`level, when the transmitting portion of the trans
`ceiver is transmitting;
`biasing the amplifying means to a relatively high
`level, when the transmitting portion is not transmit
`ting and the sensed signal received by the receiving
`portion is relatively weak; and
`-
`biasing the amplifying means to a relatively low level,
`when the transmitting portion is not transmitting
`and the sensed signal received by the receiving
`portion is relatively strong.
`7. A method according to claim 6 wherein the ampli
`fying means includes a compression point which is set to
`a level sufficient to meet sensitivity requirements of the
`receiving portion.
`
`* i i 1
`
`it
`
`15
`
`25
`
`55
`
`65
`
`TCL EXHIBIT 1085
`Page 7 of 7