Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
  • H04B1/005—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
  • H03F1/42—Modifications of amplifiers to extend the bandwidth
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
  • H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
  • H03F3/24—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers of transmitter output stages
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
  • H03F3/72—Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
  • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
  • H03H7/38—Impedance-matching networks
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
  • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
  • H03H7/46—Networks for connecting several sources or loads, working on different frequencies or frequency bands, to a common load or source
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F2200/00—Indexing scheme relating to amplifiers
  • H03F2200/111—Indexing scheme relating to amplifiers the amplifier being a dual or triple band amplifier, e.g. 900 and 1800 MHz, e.g. switched or not switched, simultaneously or not
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F2200/00—Indexing scheme relating to amplifiers
  • H03F2200/429—Two or more amplifiers or one amplifier with filters for different frequency bands are coupled in parallel at the input or output
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
  • H03F2203/72—Indexing scheme relating to gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal
  • H03F2203/7209—Indexing scheme relating to gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal the gated amplifier being switched from a first band to a second band
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
  • H03F2203/72—Indexing scheme relating to gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal
  • H03F2203/7236—Indexing scheme relating to gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal the gated amplifier being switched on or off by putting into parallel or not, by choosing between amplifiers by (a ) switch(es)
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
  • H04B1/02—Transmitters
  • H04B1/04—Circuits
  • H04B1/0458—Arrangements for matching and coupling between power amplifier and antenna or between amplifying stages
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
  • H04B1/02—Transmitters
  • H04B1/04—Circuits
  • H04B1/0483—Transmitters with multiple parallel paths

Definitions

• the present invention relates generally to power amplifiers and in particular to a dual-band, dual-mode power amplifier.
• cellular operating licenses have been awarded by the Federal Communication Commission (FCC) pursuant to a licensing scheme which divides the country into geographic service markets.
• FCC Federal Communication Commission
• RF radio frequency
• Most 800 MHz cellular telephone systems in the United States utilize the Advanced Mobile Phone Service (AMPS) analog air interface standard.
• AMPS Advanced Mobile Phone Service
• D-AMPS later generation air interface standard for the 800 MHz band, known as D-AMPS
• the D-AMPS standard comprises both digital and analog cellular communication.
• AMPS analog
• D-AMPS digital
• PCS personal communications services
• Operational PCS systems such as systems based on the GSM TDMA (Time Division Multiple Access) or IS-95 CDMA (Code Division Multiple Access) air interface standards, are being implemented in the United States in the 1900 MHz frequency range. Meanwhile, existing 800 MHz cellular systems are continuing to operate .
• GSM TDMA Time Division Multiple Access
• CDMA Code Division Multiple Access
• a mobile transceiver is capable of both dual-mode and dual-band operation to provide the user with maximum flexibility and functionality.
• the power amplifier used in a mobile transceiver is typically optimized for use in a particular band (i.e. PCS or AMPS) and in a particular mode (i.e. analog or digital) .
• This problem is manifested in two ways: as an impedance matching problem and as an amplifier biasing problem.
• the impedance at the output of the amplifier must be matched to the impedance of a duplexer/diplexer prior to transmission.
• the impedance of the matching circuit is dependent on the frequency of operation.
• a conventional matching circuit optimized for matching the impedance of an amplifier at 800 MHz will generally not optimally match the impedance of the same amplifier operating at 1900 MHz.
• the impedance of the amplifier is dependent on the mode of operation.
• a conventional matching circuit optimized for matching the impedance of an amplifier operating at 800 MHz in the AMPS mode will not adequately match the impedance of the same amplifier operating at 800 MHz in the D-AMPS digital mode.
• the biasing problem arises due to the fact that the efficiency of an amplifier is dependent on the mode or class of operation of the amplifier which is determined by the modulation technique employed.
• analog communication systems employ well known frequency modulation (FM) techniques to modulate analog information onto a carrier signal
• digital communication systems employ digital modulation schemes, such as ⁇ /4 DQPSK (Differential Quadrature Phase Shift Keying) modulation.
• Signals transmitted using frequency modulation are most efficiently amplified by a power amplifier biased and operating in non-linear or saturated mode.
• Signals transmitted using ⁇ /4 DQPSK modulation are most efficiently amplified by a power amplifier biased and operating in linear mode.
• a power amplifier circuit having a driver amplifier stage including a low band driver amplifier and a high band driver amplifier.
• a final amplifier stage includes a linear mode amplifier for amplifying digitally modulated signals and a saturated (nonlinear) mode amplifier for amplifying frequency modulated (analog) signals.
• a switching network interconnects the driver amplifier stage and the final amplifier stage.
• an appropriate driver amplifier can be coupled to an appropriate final amplifier to most effectively and efficiently amplify analog or digital RF signals in either of a plurality of frequency bands .
• a diplex matching circuit is coupled to the linear mode final amplifier for impedance matching and for separating D- AMPS (800 MHz band) and PCS (1900 MHz band) digital signals.
• a power impedance matching circuit is coupled to the output of the saturated mode final amplifier.
• the amplifier circuit includes means for selectably placing the amplifier circuit in a linear mode or a saturated mode, corresponding to digital and analog modes of operation of the radiotelephone, respectively.
• the linear final amplifier is biased in the on state and the saturated mode amplifier may be biased in the off state.
• the saturated mode final amplifier is biased in the on state and the linear amplifier may be biased in the off state.
• the amplifier circuit may include means for selectably coupling either the first diplex matching circuit output or the low pass matching circuit output to an output line when the amplifier circuit is selectably placed in linear mode or saturated mode, respectively.
• Figure 1 is a schematic diagram of a dual amplifier chain configuration known in the art.
• Figure 2 is a schematic diagram of a single amplifier chain with diplex power matching circuit for dual band operation.
• Figure 3 is a schematic diagram of a dual band, dual mode amplifier chain.
• Figure 4 is a schematic diagram of another embodiment of a dual band, dual mode amplifier chain.
• Figure 5 is a circuit diagram of a harmonic trap for use with the embodiment of Figure 4.
• duplexer and diplexer both refer to a three port, frequency selective splitter.
• a duplexer is used to enable an RF transceiver to simultaneously transmit and receive on nearly adjacent frequencies using a common antenna, whereas a diplexer separates input signals into high band or low band signals.
• a dual-band power amplifier circuit is indicated generally by reference numeral 200.
• Power amplifier circuit 200 has a diplex matching circuit 205 for matching the impedance of a multi-band power amplifier.
• Radio Frequency (RF) signals are input to a multi-band amplifier 220 at RF input port 210.
• Amplifier 220 amplifies the RF signals and outputs the amplified RF signals to a diplex power matching circuit 205 at port 225.
• the amplified RF signals may fall into one of two frequency bands.
• the present invention could modified for use in connection with a power amplifier capable of amplifying RF signals contained in more than two frequency bands .
• RF signals falling in the first frequency band will be passed by filter/match circuit 230 to duplexer 235.
• RF signals falling in the second frequency band will be passed by filter/match circuit 240 to duplexer 245.
• Filter/match circuit 230 blocks RF signals in the second frequency band while providing a suitable impedance match for signals in the first frequency band.
• filter/match circuit 240 blocks RF signals in the first frequency band while providing a suitable impedance match for signals in the second frequency band.
• RF signals passed by filter/match circuit 230 are passed through duplexer 235 (if necessary) and into diplexer 260 for transmission using antenna 270.
• duplexer 235 may or may not be necessary.
• RF signals passed by filter/match circuit 240 are passed through duplexer 245 and into diplexer 260 for transmission using antenna 270.
• a dual-mode, dual-band amplifier circuit is indicated generally by reference numeral 300.
• Amplifier circuit 300 is advantageously included in the transmitter or transceiver of a radiotelephone (not shown) for amplifying both analog and digital signals in two different frequency bands or ranges, thereby providing the radiotelephone with dual-band, dual-mode functionality.
• Amplifier circuit 300 includes an RF input port 302 which is coupled to a mode select switch 304. Depending on whether the radiotelephone is being operated in a digital or analog mode, the setting of mode select switch 304 will cause input RF signals to be transmitted down digital path 306 or analog path 308, respectively.
• mode select switch 304 is controlled by a mode control signal from a microprocessor (not shown) within the radiotelephone.
• the control signal provided by the microprocessor is used to selectively place amplifier circuit 300 in a linear mode or a saturated (nonlinear) mode of operation.
• Digital path 306 includes a linear amplifier 310, which efficiently amplifies signals which have been modulated using a linear modulation technique such as DQPSK modulation.
• the output of linear amplifier 310 is coupled to a diplex matching circuit 330 which efficiently separates 1900 MHz signals from 800 MHz signals while providing an impedance match for linear amplifier 310 in both frequency ranges.
• diplex matching circuit 330 The structure and function of diplex matching circuit 330 is described in greater detail below.
• Diplex matching circuit 330 has a 1900 MHz output 334 and an 800 MHz output 336.
• the 1900 MHz output is coupled via path 339 to a diplexer 370, which couples the 1900 MHz output signal to an antenna 380.
• a duplexer may be provided between the 1900 MHz output 334 and diplexer 370 if full duplex operation is desired for 1900 MHz operation, for example in a CDMA or multirate TDMA system.
• Analog path 308 includes a nonlinear amplifier 320 which efficiently amplifies frequency modulated signals.
• the output of nonlinear amplifier 320 is coupled to a matching circuit 340 which provides a 50-Ohm impedance match for nonlinear amplifier 320.
• Matching circuit 340 also helps suppress harmonic content that could feed back down the 1900 MHz path 339.
• the nonlinear amplifier may be operated as a deeply saturated Class C amplifier or as a switched mode class E amplifier.
• Previous solutions in which a single amplifier was used for both linear and nonlinear amplification required that the amplifier be biased (in Class AB) to barely meet linearity requirements while retaining as much nonlinear efficiency as possible. The result was a blended match that was not optimal for either linear or nonlinear amplification.
• the present invention overcomes this limitation while providing an amplifier circuit that can effectively and efficiently amplify signals in different frequency bands .
• the output of matching circuit 340 on line 345 and the 800 MHz output of diplex matching circuit 330 on line 338 are provided to a high power switch 350.
• High power switch 350 couples either the 800 MHz output of diplex match circuit 330 (corresponding to a digital 800 MHz signal) or the output of matching circuit 340 (corresponding to an analog 800 MHz signal) to duplexer 360 via output line 361, depending on whether the cellular telephone is being operated in a digital or analog mode, respectively.
• mode select switch 304 high power switch 350 is controlled by the mode control signal from the radiotelephone's microprocessor. Additionally, high power switch 350 provides isolation for linear amplifier 310, thus preventing linear amplifier 310 from being loaded by nonlinear amplifier 320 and matching circuit 340.
• DC biasing for linear amplifier 310 and nonlinear amplifier 320 is provided by switching Vcc inputs 316, 326 on or off depending on the desired mode of operation of the cellular telephone (i.e. digital or analog).
• Duplexer 360 is a conventional duplexer designed to permit full duplex operation at 800 MHz. Duplexer 360 couples 800
• MHz signals to diplexer 370, which in turn couples the signals to antenna 380 for transmission.
• the embodiment illustrated in Figure 3 is particularly suited for use in a TDMA transceiver, which operates at half duplex at 1900 MHz.
• the circuit can be easily adapted for use in a CDMA or multirate TDMA transceiver by providing an additional duplexer in path 339 to permit full duplex operation at 1900 MHz.
• Diplex matching circuit 330 which is essentially the same circuit as diplex matching circuit 205 shown in Figure 2, is described in detail in copending U.S. application serial no. 08/888,168 (Attorney Docket EUS00502) and will not be discussed further. The embodiment illustrated in Figure 3 and implementations thereof are described in greater detail in copending U.S. patent application serial no. 08/939,870 (Attorney Docket EUS00806) .
• a second dual-band dual-mode amplifier architecture is indicated generally as 400.
• Amplifier 400 improves on the designs illustrated in Figures 2 and 3 by separating the amplifier into a driver stage and a final stage, and selectively coupling the appropriate driver and final stages depending on the desired mode of operation of the amplifier 400.
• Amplifier 400 includes a 1900 MHz driver amplifier 402 tuned and biased to efficiently amplify signals in the 1900 MHz frequency band and an 800 MHz driver amplifier 412 tuned and biased to efficiently amplify signals in the 800 MHz frequency band.
• Amplifier 400 also includes a pair of final stage amplifiers 404 and 414.
• Final stage amplifier 404 is biased and tuned for linear operation as a class AB amplifier to efficiently amplify digitally modulated RF signals, while final stage amplifier 414 is biased and tuned for saturated operation in an efficient mode of operation, such as a deeply saturated class C amplifier or a switched mode class E amplifier or some other highly efficient mode of operation to efficiently amplify frequency modulated analog RF signals.
• an efficient mode of operation such as a deeply saturated class C amplifier or a switched mode class E amplifier or some other highly efficient mode of operation to efficiently amplify frequency modulated analog RF signals.
• the driver stage amplifiers 402, 412 are connected to the final stage amplifiers 404, 414 by means of a switching network 418 which includes switches 422, 424 and 426.
• switches 422, 424 and 426 may be a field-effect transistor (FET) switch whose design is well known to those skilled in the art. Other suitable types of switches may be substituted by those having skill in the art.
• FET field-effect transistor
• the open/closed state of switches 422, 424 and 426 is controllable by means of control lines (not shown) from an associated microprocessor or other control logic (not shown) .
• Switch 422 couples the output of 1900 MHz driver amplifier 402 to the input of linear final amplifier 404.
• the output of 800 MHz driver amplifier 412 is coupled to node 428. Node 428 is in turn coupled to the input of linear final amplifier 404 via switch 424 and to the input of saturated final amplifier 414 via switch 426.
• the signal output by final amplifier 404 is passed through diplex matching circuit 430 which filters and passes the signal to duplexer 460 (if necessary) or duplexer 465 (via switch 445) depending on the frequency content of the signal.
• a first filter 410 is provided between the output of 1900 MHz driver amplifier 402 and switch 422, and a second filter 420 is provided between the output of 800 MHz driver amplifier 412 and node 428.
• These filters 410, 420 filter the input signals prior to the final gain stage thereby providing receive band noise rejection and reduction of the harmonic content of the signal.
• Filters 410, 420 are surface acoustic wave (SAW) bandpass filters, the design of which is well known in the art.
• SAW surface acoustic wave
• a harmonic trap 455 is coupled to the input of diplex matching circuit 430. The function of harmonic trap 455 is to reduce the harmonic content of signals output by diplex matching circuit 430 and to supply VDD to final stage amplifier 404.
• FIG. 5 shows an embodiment of harmonic trap 455, which includes a high-power switch 510 coupled to a pair of parallel switchable inductors 520, 525. Inductors 520, 525 are in turn coupled to capacitor 530, which is coupled to the input of diplex matching circuit 430. Inductor 520 and capacitor 530 combine to form a parallel resonant circuit that is resonant at 800 MHz, while inductor 525 and capacitor combine to form a parallel resonant circuit that is resonant at 1900 MHz.
• switch 510 depending on the state of switch 510 (which is set according to the operating state of amplifier 400) , the harmonic trap 455 will operate to attenuate harmonic signals in the 800 MHz band or the 1900 MHz band.
• switch 510 is controllable by means of control lines (not shown) from an associated microprocessor or other control logic (not shown) .
• the amplifier may be operated in one of a number of selectable modes to amplify analog or digital signals in the 800 MHz frequency band or digital signals in the 1900 MHz frequency band.
• switch 422 is closed, while switch 424 is open.
• switch 426 may be open to provide additional isolation of the final stage amplifiers 404, 414.
• Digitally modulated input signals in the 1900 MHz frequency band are input to amplifier 400 via input terminal 405 and provided to 1900 MHz driver amplifier 402.
• the signal output by 1900 MHz driver amplifier 402 is coupled to the input of final amplifier 404 which, as noted above, is biased for operation in linear mode.
• Amplifier 404 efficiently amplifies the digitally modulated signal and outputs the amplified signal to diplex matching circuit 430.
• switches 422 and 424 are open, while switch 426 is closed.
• Frequency modulated (i.e. analog or FM) input signals in the 800 MHz frequency band are input to amplifier 400 via input terminal 415 and provided to 800 MHz driver amplifier 412.
• the signal output by 800 MHz driver amplifier 412 is coupled to the input of final amplifier 414 via closed switch 426.
• Final amplifier 414 is biased for operation in saturated mode, and therefore efficiently amplifies the FM signal and outputs the amplified signal to matching circuit 440.
• switches 422 and 426 are open, while switch 424 is closed.
• Digitally modulated input signals in the 800 MHz frequency band are input to amplifier 400 via input terminal 415 and provided to 800 MHz driver amplifier 412.
• the signal output by 800 MHz driver amplifier 412 is coupled to the input of final amplifier 404 via node 428 and switch 426.
• final amplifier 404 is biased for operation in linear mode.
• Amplifier 404 efficiently amplifies the digitally modulated signal and outputs the amplified signal to diplex matching circuit 430.
• the operation of switch 445 is similar to that of switch 350 described in reference to Figure 3.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Amplifiers (AREA)

Priority Applications (5)

Applications Claiming Priority (1)

Publications (1)

Family

ID=11004874

Family Applications (1)

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Cited By (11)

Families Citing this family (7)

Citations (6)

• 1999
  • 1999-07-07 JP JP2001509150A patent/JP2003504929A/ja not_active Withdrawn
  • 1999-07-07 WO PCT/IB1999/001255 patent/WO2001005028A1/en active Application Filing
  • 1999-07-07 CN CN99816896.3A patent/CN1367952A/zh active Pending
  • 1999-07-07 DE DE19983968T patent/DE19983968T1/de not_active Withdrawn
  • 1999-07-07 AU AU45278/99A patent/AU4527899A/en not_active Abandoned

Patent Citations (6)

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