(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2002/0039891 A1
`Lokc ct al.
`(43) Pub. Date:
`Apr. 4, 2002
`
`US 20020039891A1
`
`(54) SYSTEM AND METHOD FOR
`DYNAMICALLY VARYING OPERATIONAL
`
`PARAMETERS OF AN AMPLIFIER
`
`(76)
`
`Inventors: Aravind Loke, Irvine, CA (US); Mohy
`F, Abdelgany, Irvine, CA (US); James
`F. Kamke, Riverside, IL (US)
`
`Correspondence Address:
`KNOBBE MARTENS OLSON & BEAR LLP
`520 NEWPORT CENTER DRIVE
`SIXTEENTH FLOOR
`NEWPORT BEACH, CA 92660 (Us)
`
`(21) Appl, No;
`
`10/004,438
`
`(22)
`
`Filed:
`
`Oct. 23, 2001
`
`Related U.S. Application Data
`
`(63) Continuation of application No. 09/222,686, filed on
`Dec. 29, 1998, now patented.
`
`Publication Classification
`
`Int. Cl.7 ..................................................... .. H04B 1/04
`(51)
`(52) U.S. Cl.
`......................... .. 455/127; 455/573; 455/574
`
`ABSTRACT
`(57)
`Awireless communications device uses an amplifier module
`to transmit signals. The amplifier module is configured to
`amplify a signal. The amplifier module includes an amplifier
`circuit and a control module. The control module is config-
`ured to vary the operating parameters of the amplifier circuit
`based on a desired output power level. The control module
`relies on stored data values to dynamically vary the oper-
`ating parameters of the amplifier circuit so as to increase the
`efficiency of the amplifier circuit.
`
`//5
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`
`Kinetic Technologies,
`
`Inc.
`
`Exhibit 1002
`
`Page 1
`
`

`

`Patent Application Publication
`
`Apr. 4, 2002 Sheet 1 of 7
`
`US 2002/0039891 A1
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`

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`Patent Application Publication
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`Apr. 4, 2002 Sheet 2 of 7
`
`US 2002/0039891 A1
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`

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`Patent Application Publication
`
`Apr. 4, 2002 Sheet 3 of 7
`
`US 2002/0039891 A1
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`Patent Application Publication
`
`Apr. 4, 2002 Sheet 5 of 7
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`US 2002/0039891 A1
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`

`

`Patent Application Publication
`
`Apr. 4, 2002 Sheet 6 of 7
`
`US 2002/0039891 A1
`
`POWER
`
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`
`/575,55
`
`Page 7
`
`

`

`Patent Application Publication
`
`Apr. 4, 2002 Sheet 7 of 7
`
`Us 2002/0039391 A1
`
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`Page 8
`
`

`

`US 2002/0039891 A1
`
`Apr. 4, 2002
`
`SYSTEM AND METHOD FOR DYNAMICALLY
`VARYING OPERATIONAL PARAMETERS OF AN
`AMPLIFIER
`
`[0001] RELATED APPLICATION
`
`[0002] This application is a continuation of prior applica-
`tion Ser. No. 09/222,686, filed on Dec. 29, 1998.
`
`BACKGROUND OF THE INVENTION
`
`[0003]
`
`1. Field of the Invention
`
`to electronic
`invention generally relates
`[0004] The
`devices. More particularly, the invention relates to a com-
`munications device and a transmitter included therein.
`
`[0005]
`
`2. Background
`
`[0006] There is an ever present need to reduce the power
`consumption of electronic devices. For example, a laptop
`computer or a wireless phone typically includes a battery to
`store and provide electrical energy for the operation of the
`electronic device. A user can operate the electronic device
`through the battery when no other source of electrical energy
`is available, or when the user wants to be mobile. Batteries,
`however, store only a limited amount of electrical energy,
`which is consumed by the electronic device.
`
`[0007] The batteries, thus, have to be recharged after the
`electronic device has been used for a certain time. The time
`
`is
`interval between two subsequent charging events
`for
`expressed as operating time.
`In wireless phones,
`example, the operating time can further be divided into a
`stand-by time and a talk time.
`
`[0008] The user of a wireless communications device such
`as a mobile unit or a cellular phone typically desires to have
`an operating time, particularly a talk time, which is as long
`as possible. Additionally,
`the user generally expects the
`wireless device to be as small and as light as possible.
`Because the operating time is dependent from the capacity
`and, thus, usually from the size of the battery, small size, low
`weight, long operating time of the wireless, device are often
`contradictory expectations.
`
`[0009] To fulfill these expectations, manufacturers seek to
`increase the capacity of the batteries without increasing the
`size and weight of the batteries. In addition, manufacturers
`of wireless devices have developed wireless devices which
`operate at lower voltages, for example 3.3 volts, to increase
`the stand-by time and the talk time.
`
`SUMMARY OF THE INVENTION
`
`In one embodiment, a communications device uses
`[0010]
`an amplifier module to transmit signals. The amplifier mod-
`ule is configured to amplify a signal. The amplifier module
`includes an amplifier circuit and a control module. The
`control module is configured to vary the operating param-
`eters of the amplifier circuit based on a desired output power
`level. The control module relies on stored data values to
`
`dynamically vary the operating parameters of the amplifier
`circuit so as to increase the efficiency of the amplifier circuit.
`
`[0011] The transmit power of a communication device,
`typically varies depending on the transmit conditions, the
`proximity of the communications device to a base station,
`etc. For example, a communications device may transmit at
`maximum power when poor transmit conditions exist. In
`
`many devices, the output power amplifier is optimized to
`generate the maximum power output.
`
`If the transmit conditions are favorable or if a
`[0012]
`communications device is near a base station, the commu-
`nications device often transmits at less than the maximum
`
`output power. Statistically speaking, a communications
`device typically spends most of its operational life trans-
`mitting at less than maximum power. For example, in a code
`division multiple access (CDMA) cellular phone, most of
`the time the phone operates below the maximum power
`output level within a range from about -5 dBm (measured
`decibels referenced to a power of 1 milliwatt) to about +8
`dBm. Accordingly, one embodiment of
`the invention
`increases the output power efficiency when an electronic
`devices operates at a lower output power level.
`
`In another embodiment of the invention, a wireless
`[0013]
`communications device has an amplifier module which is
`configured to amplify a radio frequency (RF) signal with
`increased efficiency. The amplifier module comprising an
`input terminal which receives a control signal comprising a
`plurality of pulses, wherein the number of pulses within a
`predetermined time period identify a desired power level.
`
`[0014] The amplifier module further comprising a control
`circuit in communication with the control signal. The control
`circuit comprising at least one counter which counts the
`number of pulses occurring within the predetermined time
`period so as to generate a control value.
`
`[0015] The amplifier module further comprising a first
`memory array in communication with the control value. The
`first memory array comprising multiple entries, each entry
`comprising a power value, wherein the first memory outputs
`the power value which corresponds to the control value. The
`amplifier module further comprising a second memory array
`in communication with the control value. The second
`
`memory array comprising multiple entries, each entry com-
`prising a bias value, wherein the second memory outputs the
`bias value which corresponds to the control value.
`
`[0016] The amplifier module further comprising an ampli-
`fier circuit which is in communication with the power value,
`the bias value and a radio frequency (RF) signal. The
`amplifier circuit is configured to vary the amplification of
`the radio frequency signal based on the power and bias
`values, wherein the power and bias values increase the
`efficiency of the amplifier circuit at the desired power level.
`
`In another embodiment, the power values deter-
`[0017]
`mine the amount of power voltage applied to the amplifier
`circuit. In yet another embodiment, the bias values deter-
`mine the amount of bias voltage applied to the amplifier
`circuit. In an additional embodiment, the first and second
`memory arrays are located in a single memory array.
`
`In one embodiment, the power value is a digital
`[0018]
`power value. In another embodiment, the communications
`device further comprises a digital-to-analog converter which
`converts the digital power value to an analog power value.
`In yet another embodiment, the bias value is a digital bias
`value. In an additional embodiment, the communications
`device further comprises a digital-to-analog converter which
`converts the digital bias value to an analog bias value.
`
`In one embodiment, the radio frequency signal is a
`[0019]
`Global System for Mobile Communications (GSM) com-
`
`Page 9
`
`

`

`US 2002/0039891 A1
`
`Apr. 4, 2002
`
`munications signal. In another embodiment, the radio fre-
`quency signal is a Personal Communications System (PCS)
`communications signal. In yet another embodiment,
`the
`radio frequency signal is an Advanced Mobile Phone Sys-
`tems (AMPS) communications signal.
`
`In one embodiment, the radio frequency signal is
`[0020]
`compatible with the code division multiple access (CDMA)
`standard. In another embodiment, the radio frequency signal
`is compatible with the frequency division multiple access
`(FDMA) standard. In yet another embodiment, the radio
`frequency signal is compatible with the time division mul-
`tiple access (TDMA) standard.
`
`[0021] One embodiment of the invention relates to an
`amplifier control circuit comprising an input which receives
`a first signal
`indicative of a desired power level. The
`amplifier control circuit further comprising a memory. The
`memory comprising a plurality of data values wherein the
`data values represent amplifier operational parameters.
`
`[0022] The amplifier control circuit further comprising a
`control circuit in communication with the input and the
`memory. The control circuit configured to access at least one
`of the data values in the memory in response to the first
`signal. The control circuit further configured to generate a
`second signal based on the selected data value.
`
`In one embodiment, the first signal includes pulses
`[0023]
`of varying duration which are indicative of the desired
`power level. In another embodiment,
`the control circuit
`includes a counter which counts the pulses to generate a
`value representing the counted pulses within a predeter-
`mined period of time. The value being indicative of the
`desired power level.
`
`In one embodiment, the data values represent val-
`[0024]
`ues for powering an amplifier circuit. In another embodi-
`ment, the data values represent values for biasing an ampli-
`fier circuit. In yet another embodiment, the first signal is a
`digital signal. In an additional embodiment, the first signal
`transmits a digital value. In another embodiment, the data
`values represent values for biasing an amplifier circuit.
`
`[0025] One embodiment of the invention relates to an
`amplifier control circuit comprising a first means for storing
`a plurality of data values wherein the data values represent
`amplifier operational parameters. The amplifier control cir-
`cuit further comprising a second means in communication
`with a first signal that indicates a desired power level. The
`second means using the first signal to address at least one of
`the data values in the first means. The second means also
`
`generating a second signal based on the addressed data
`value.
`
`[0026] One embodiment of the invention relates to a
`method for increasing the power efficiency of an amplifier
`module. The method comprising the act of receiving a first
`control signal indicative of a power level output of the
`amplifier module. The method further comprising the act of
`using the control signal to address memory locations, each
`memory location storing at least one operating characteristic
`of the amplifier module. The method further comprising the
`act of reading from the addressed storage locations to
`generate at least a second control signal, the second control
`signal configured to increase the power efficiency of the
`amplifier module.
`
`In one embodiment, the control signal is a pulse
`[0027]
`duration modulation signal. In another embodiment,
`the
`method further comprising the act of counting the pulses of
`the control signal within a predetermined period of time to
`generate a digital value representing the power level. In yet
`another embodiment, the method further comprising the act
`of using the digital value to address the storage locations.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0028] These and other aspects, advantages, and novel
`features of the invention will become apparent upon reading
`the following detailed description and upon reference to the
`accompanying drawings.
`
`[0029] FIG. 1 is a schematic illustration of a wireless
`communications device cut away to show a portion of the
`motherboard.
`
`[0030] FIG. 2 is an illustration of one embodiment of a
`transmit path within the wireless communications device
`shown in FIG. 1.
`
`[0031] FIG. 3 is a schematic illustration of a first embodi-
`ment of a transmitter.
`
`[0032] FIG. 4 is a schematic illustration of a transmitter
`module.
`
`[0033] FIG. 5 is a schematic illustration of one embodi-
`ment of a control module included in the transmitter module
`shown in FIG. 4.
`
`[0034] FIG. 6A shows graphs illustrating power efficien-
`cies as a function of the output power of a power amplifier.
`
`[0035] FIG. 6B shows a graph illustrating a power density
`as a function of the output power of a power amplifier.
`
`[0036] FIG. 7 shows a flow chart of a control procedure.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`[0037] FIG. 1 shows a wireless communications device 3
`as an example of an electronic device. Other examples of
`electronic devices include wireless phones, cordless phones,
`mobile transmitters, stationary wireless transmitters, per-
`sonal digital assistants, wireless modems, pagers, wireless
`fax machines, and other battery operated devices.
`It
`is
`contemplated that the invention is also applicable to a wide
`range of non-portable electronic devices such as modems,
`cable modems, fax machines, base stations, land-line based
`applications, computer network applications and the like.
`Further, it is contemplated that the invention is generally
`applicable to a wide range of battery operated devices.
`Hereinafter, one embodiment of the invention is described
`with reference to a cellular phone which is one embodiment
`of the wireless communications device 3.
`
`[0038] The cellular phone operates within a mobile com-
`munications system. A mobile communications system, for
`example a code division multiple access (CDMA) system, is
`structured to have a variety of individual regions called cells,
`and to comprise a variety of fixed transceiver stations called
`base transceiver stations, and a plurality of mobile stations,
`the cellular phones. Usually, one base transceiver station
`defines one cell and handles telephone traffic to and from the
`cellular phones which are currently located in the cell.
`
`Page 10
`
`

`

`US 2002/0039891 A1
`
`Apr. 4, 2002
`
`[0039] The wireless communications device 3 is exem-
`plary described as, but not limited to, a wireless phone for
`a CDMA system. Hereinafter, the wireless communications
`device 3 is referred to as the phone 3. Aportion of the case
`of the phone 3 is cut away to show a motherboard 5 of the
`phone 3 with a transmitter module 1 positioned thereon.
`Although not shown in FIG. 1, those skilled in the art will
`appreciate that the phone 3 comprises a plurality of other
`components and functional modules, such as the compo-
`nents included in a receive path and a transmit path. For
`example, the phone 3 further includes a central processing
`unit (CPU), an antenna 2, a display and a keypad.
`
`In one embodiment, the transmitter module 1 is
`[0040]
`configured to emit radio frequency (RF) signals. The trans-
`mitter module 1 comprises an amplifier stage for amplifying
`the RF signals according to electrical characteristics such as
`a defined nominal effective radiated power (ERP). In cellular
`CDMA systems, the phones are grouped into three catego-
`ries Class I, Class II and Class III having different ranges of
`effective radiated powers. For example, a Class I phone
`emits an effective radiated power of 1.25 watts to 6.3 watts
`and a Class III phone emits an effective radiated power of
`0.2 watts to 1 watt. Further electrical characteristics are
`
`described in TIA/EIA/IS-98A,
`10.4.5.3-1.
`
`for example,
`
`in Table
`
`it is contemplated that the
`[0041] Regarding operation,
`phone 3 can operate for systems that use the code division
`multiple access
`(CDMA),
`frequency division multiple
`access (FDMA), and time division multiple access (TDMA)
`standards. Furthermore, it is contemplated that the phone 3
`can operate in frequency bands used for wireless commu-
`nications. For example, the phone 3 can be configured to
`receive and transmit data according to the Global System for
`Mobile Communications (GSM) standard which typically
`operates in the 900 MHZ and 1800 MHZ ranges.
`
`the phone 3 can be configured to
`[0042] Furthermore,
`receive and transmit data according to the Personal Com-
`munications System (PCS) standard. In PCS systems, the
`phone 3 operates in a transmit band between 1850 MHZ and
`1910 MHZ and a receive band between 1930 MHZ and 1990
`
`MHZ. The phone 3 can also be configured to receive and
`transmit data according to the Advanced Mobile Phone
`Systems (AMPS) standard. In an AMPS system, the phone
`3 operates in a transmit band between 824 MHZ and 849
`MHZ and a receive band between 869 MHZ and 894 MHZ.
`
`In addition, it is contemplated that in one embodi-
`[0043]
`the phone 3 can be configured to operate as a
`ment,
`dual-band phone and as a dual-mode phone. For example,
`the phone 3 can be configured to include a dual-band
`transmitter so that the phone 3 can operate both in the
`CDMA frequency bands and PCS frequency bands.
`In
`addition, the phone 3 can be configured as a dual-mode
`phone to operate in the CDMA mode or in a mode for AMPS
`communication devices.
`
`[0044] FIG. 2 illustrates an embodiment of the transmit
`path of the phone 3. Within the cellular phone 3,
`the
`transmitter module 1 and a processing module 7 are posi-
`tioned on the motherboard 5 and interconnected between the
`
`antenna 2 and a microphone 9 of the phone 3. In the
`illustrated embodiment, the processing module 7 performs
`most speech and signal processing in a transmit direction,
`for example, voice encoding and channel encoding. Amodu-
`
`lator, included either in the signal processing module 7 or the
`transmitter module 1, modulates a RF carrier of,
`for
`example, about 824 MHZ with the processed speech signal.
`The carrier frequency of 824 MHZ is selected from a
`transmit band defined for CDMA systems. The transmit
`band is approximately between 824 MHZ and 849 MHZ. For
`PCS systems, the RF carrier is selected from the transmit
`band between 1850 MHZ and 1910 MHZ as discussed above.
`
`[0045] The receive path is indicated by means of a
`receiver module 1a which includes, for example, a radio
`frequency (RF) receiver. The transmitter module 1 and the
`receiver module 1a are connected to the antenna 2 through
`an electronic switch 2a which connects the antenna 2 either
`to the transmitter module 1 or the receiver module 1a. The
`
`CPU of the phone 3 operates the electronic switch 2a in
`accordance with a transmission protocol
`to avoid,
`for
`example, that the receiver 1a receives a signal the transmit-
`ter module 1 emits. In cellular CDMA systems, for example,
`a duplexer ensures that the receiver 1a does not receive the
`signal emitted from the transmitter module 1.
`
`[0046] FIG. 3 shows an exemplary block diagram of the
`transmitter module 1 shown in FIG. 2. Electrical circuits or
`devices such as the receiver module 1a and the transmitter
`
`module 1 can be implemented in a single-ended version or
`a differential version. The differential version is advanta-
`
`geously used to improve the electrical circuits with respect
`to noise and undesired signal components. In the differential
`version, the transmitter module 1 is connected to the signal
`processing module 7 through two differential
`lines. The
`differential lines are typically referred to as inverted and
`non-inverted, or “+” and “—”. The block diagram of FIG. 3,
`however, shows the transmitter module 1 in the single-ended
`version. Those skilled in the art will appreciate that a
`differential version can be implemented by adapting the
`components to receive, process and output signals on two
`lines.
`
`[0047] The transmitter module 1 includes a modulator
`module 12 and an amplifier module 10. The modulator
`module 12 is connected between the signal processing
`module 7 and the amplifier module 10. The modulator
`module 12 includes mixer and driver stages as described
`below. In one embodiment, the amplifier module 10 is a
`multiple-stage amplifier operating as a power amplifier. An
`input 14 of the amplifier module 10 is connected to the
`modulator module 12 and an output 16 of the amplifier
`module 10 is connected to the antenna 2.
`
`[0048] Acontroller 17 located within the phone 3 controls
`and monitors the modulator module 12 and the amplifier
`module 10. For instance, the controller 17 can be associated
`with a power management system of the phone 3. The power
`management system is responsible for controlling the power
`level with which the RF signals are transmitted. The power
`level depends, for example, on the distance between the
`phone 3 and a base transceiver station, and the characteris-
`tics of a propagation path between the phone 3 and the base
`transceiver station. The power level requirements are trans-
`mitted between the phone 3 and the base transceiver station
`by means of a communications protocol typically used in
`CDMA systems. The controller 17 can be the central pro-
`cessing unit (CPU) of the phone 3 or a subprocessor in
`communication with the CPU.
`In one embodiment,
`the
`power management system is implemented in a subproces-
`sor which communicates with the CPU.
`
`Page 11
`
`

`

`US 2002/0039891 A1
`
`Apr. 4, 2002
`
`[0049] The modulator module 12 of the transmitter mod-
`ule 1 includes two mixer stages formed by mixers 25, 22 in
`combination with local oscillators 30, 31 respectively. In
`FIG. 3, the local oscillators 30, 31 are shown as being part
`of the modulator module 12. However, it is contemplated
`that the local oscillators 30, 31 can be located at other
`locations within the phone 3. Further, it is contemplated that
`the grouping into the modulator module 12 and the amplifier
`module 10 is arbitrary and that this grouping is for descrip-
`tive purposes only.
`
`[0050] The mixer 25 is configured as a QPSK modulator
`(Quadrature Phase Shift Keying) which receives “I” and “Q”
`components of a baseband signal from the signal processing
`module 7 and a signal LO1 from the local oscillator 30. In
`one embodiment, the local oscillator 30 is adjustable so that
`the signal LO1 has a frequency in a range of about 100 to
`640 MHZ. The mixer 25 (QPSK modulator) modulates the
`signal LO1 with the incoming baseband signal so that an
`intermediate frequency signal results (indicated as “IF” and
`hereinafter referred to as IF signal). The IF signal includes
`the desired intermediate frequency, but also undesired fre-
`quencies which may cause noise in the IF signal. The IF
`signal is fed to an amplifier 20 which is controlled by a
`control signal AGC generated by the controller 17. The
`controller 17 is connected to the amplifier 20 via a control
`line 20a.
`
`[0051] The amplifier 20 is configured to have a variable
`gain which is adjusted by the control signal AGC thereby
`implementing an automatic gain controlled amplifier. In one
`embodiment, the amplifier 20 has a dynamic range of about
`90 dB and the control signal AGC can have a DC voltage
`between 0.2 V and 2.5 V to control the gain of the amplifier
`20.
`
`[0052] The amplifier 20 outputs an amplified IF signal to
`a bandpass filter 21. The bandpass filter 21 has a filter
`characteristic selected to pass the intermediate frequency
`and to block the undesired frequencies to reduce noise in the
`IF signal. In one embodiment, the bandpass filter 21 has a
`passband of about +/-650 kHZ. In FIG. 3, the output of the
`bandpass filter 21 is indicated as “Filtered IF.”
`
`[0053] The noise reduced IF signal is fed to the mixer 22.
`In one embodiment, the mixer 22 can be configured to have
`a controlled gain variation to calibrate and to compensate for
`any gain variation in the transmit path. The mixer 22
`converts the IF signal to a RF signal using a signal LO2
`generated by the local oscillator 31. In one embodiment, the
`signal LO2 has a frequency of about 955 MHZ to 979 MHZ.
`Similar to the mixer 18, the mixer 22 up-converts the IF
`signal and generates the RF signal comprising the desired
`radio frequency, but also undesired frequencies. The output
`of the mixer 22 is indicated as “RF.”
`
`[0054] The RF signal is fed to a bandpass filter 24. The
`bandpass filter 24 has a filter characteristic selected to pass
`the desired radio frequency and to block the undesired
`frequencies to reduce noise in the RF signal. In one embodi-
`ment, the bandpass filter 24 has a passband of about 25
`MHZ. In FIG. 3,
`the output of the bandpass filter 21 is
`indicated as “Filtered RF.”
`
`amplifier module 10. Because an amplifier may not be
`ideally linear, the amplifier 20 can add undesired frequency
`components to the RF signal. To eliminate these undesired
`frequency components from the RF signal, an optional
`bandpass filter 28 is connected between the amplifier 26 and
`the amplifier module 10.
`
`In FIG. 3, the bandpass filter 28 is connected to the
`[0056]
`input 14 of the amplifier module 10 which amplifies the RF
`signal. The amplifier module 10 outputs the amplified RF
`signal at the output 16 connected to the antenna 2. The
`antenna 2 emits the RF signal in a conventional manner.
`
`[0057] FIG. 4 shows an exemplary block diagram of the
`amplifier module 10. The amplifier module 10 includes an
`amplifier circuit 19 connected between the input 14 and the
`output 16. The amplifier module 10 further includes a
`control module 18 configured to control the amplifier circuit
`19. In one embodiment, the control module 18 is in com-
`munication with a control signal AGC input via the control
`line 20a. Control lines 21A, 23A connect the control module
`18 to inputs 21, 23, respectively, of the amplifier circuit 19.
`
`In the illustrated embodiment, the control module
`[0058]
`18 generates two control signals BIAS and VCC. The
`control line 21A conveys the control signal BIAS and the
`control
`line 23A conveys the control signal VCC. As
`described in further detail below, the control signals BIAS,
`VCC set
`the amplifier circuit 19 to have a predefined
`quiescent operating point (Q point). The Q point can be
`determined by a supply voltage (VCC) or a bias voltage/
`current, or both. The control module 18 is described in more
`detail below with reference to FIG. 5. The control module
`
`18 controls the amplifier circuit 19 so as to decrease power
`consumption and, thus, to increase the operating time.
`
`In one embodiment, the control module 18 can be
`[0059]
`implemented as an integrated circuit comprising DC-DC
`converters, regulators and switching circuits. Further, the
`control module 18 can be implemented within an integrated
`circuit responsible for the power management of the phone
`3.
`
`[0060] FIG. 5 is an exemplary block diagram of the
`control module 18. The control module 18 has an input 44
`for the control signal AGC conveyed via the control line
`20b, an output 46 for the control signal VCC, and an output
`48 for the control signal BIAS. As shown in FIG. 3, the
`control signal AGC originates from the controller 17. The
`controller 17 generates the control signal AGC as a function
`of the power output of the phone 3. In one embodiment, the
`control signal AGC is a pulse duration modulated (PDM)
`signal and exemplary indicated in FIG. 5. The number of
`pulses within a given count period, the density, is directly
`proportional to the power output of the phone 3. That is, the
`higher the power output, the more dense the pulses within
`the given count period.
`
`It is contemplated that in other embodiments the
`[0061]
`control signal AGC can be selected so that the amplitude or
`the phase of the pulses represent the power output of the
`phone 3. Further, it is contemplated that the control signal
`AGC can be a digital signal directly representing the power
`output of the phone 3.
`
`[0055] The filtered RF signal is fed to an amplifier 26
`which is generally configured to amplify RF signals in the
`800 MHZ range. The amplifier 26 is a drive amplifier for the
`
`In the illustrated embodiment, the control module
`[0062]
`18 includes a pulse counter 30 which receives the PDM
`signal. The pulse counter 30 is in one embodiment an
`
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`US 2002/0039891 A1
`
`Apr. 4, 2002
`
`integrated circuit which counts the pulses within the count
`period. The count is determined by a clock signal CLK
`applied to the pulse counter 30. The pulse counter 30 outputs
`a digital number which corresponds to the power output of
`the phone 3.
`
`[0063] The pulse counter 30 is connected to an input 44 of
`the control module 18 and to storage locations 32, 34. The
`storage location 32 is further connected to a digital-to-
`analog (D/A) converter 36 illustrated as “DAC.” The D/A
`converter 36 is connected to a voltage converter 40, which
`is in one embodiment a DC-DC converter having an output
`46 for the control signal VCC. The storage location 34 is
`connected to a digital-to-analog (D/A) converter 38 also
`illustrated as “DAC.” The D/A converter 38 is connected to
`a voltage converter 42, which is in one embodiment a
`DC-DC converter having an output 48 for the control signal
`BIAS.
`
`[0064] The storage locations 32, 34 receive the digital
`number output from the pulse counter 30. In one embodi-
`ment, each storage location 32, 34 is a non-volatile Read
`Only Memory (ROM). The storage locations 32, 34 store
`operating characteristics of the amplifier circuit 19. These
`operating characteristics are determined during manufac-
`ture, for example, during a calibration process of the phone
`3, and stored in the ROM. Alternatively, each storage
`location 32, 34 can be implemented as an Electrically
`Erasable Programmable Read Only Memory (EEPROM).
`The EEPROM is a non-volatile storage device in which
`bytes or words can be erased and reprogrammed individu-
`ally. In another embodiment, each storage location 32, 34
`can be a Flash EEPROM. The storage locations 32, 34 retain
`their contents even when the power is switched off.
`
`It is contemplated that in alternative embodiments
`[0065]
`the storage locations 32, 34 can be volatile memories such
`as Random Access Memories or the like. The phone 3 can
`be configured that at each power up the operating charac-
`teristics of the amplifier circuit 19 are loaded to the storage
`locations 32, 34. For instance, the phone’s CPU can initiate
`a download from an external or internal data source which
`
`provides the operating characteristics.
`
`[0066] The storage location 32 stores a look-up table for
`various digital values used to generate the control signal
`VCC. Hereinafter, the storage location 32 and the look-up
`table stored therein are referred to as the VCC look-up table
`32. The storage location 34 stores a look-up table for various
`digital values used for the control signal BIAS. Hereinafter,
`the storage location 34 and the look-up table stored therein
`are referred to as the BIAS look-up table 34.
`
`[0067] The values of the VCC look-up table 32 represent
`a variety of individual digital voltage values. In one embodi-
`ment, the digital voltage values cover a range of analog
`voltages (VCC) approximately between 2 and 5 volts. The
`voltage range covers, thus, voltages typically used for pow-
`ering an amplifier circuit. Each individual voltage value
`represents the power supply for the amplifier circuit 19. It is
`contemplated that the VCC look-up table 32 can store a
`wider range of voltage values in case the amplifier circuit 19
`is operable at a wider range of the power supply.
`
`[0068] The VCC look-up table 32 stores the individual
`voltage val