Abstract: In a representative embodiment, a multiple mode power amplifier that is operable in a first power mode and a second power mode. The multiple mode power amplifier comprises a first amplifying unit; a second amplifying unit; a first impedance matching network connected to an output port of the first amplifying unit; a second impedance matching network connected to an output port of the second amplifying unit and to the first impedance matching network; and a third impedance matching network connected to the output ports of the first and the second amplifying units. The third impedance matching network reduces a phase difference between signals amplified by the first and the second amplifying units in the first mode.

Abstract: An apparatus and method for maximizing the performance of a peaking amplifier in a Doherty amplifier are provided. The apparatus includes a splitter, a carrier amplifier, an (N?1) number of peaking amplifiers, a Doherty combiner, and an output load. The splitter splits an input signal into an ‘N’ number of power signals. The carrier amplifier amplifies the signal provided from the splitter using a first Direct Current (DC) bias. The peaking amplifiers amplify the signals provided from the splitter using a second DC bias, which is lower than the first DC bias. When the carrier amplifier and the peaking amplifiers are all operating, the Doherty combiner forms a load impedance of the respective amplifiers such that the load impedance of the peaking amplifiers are less than the load impedance of the carrier amplifier. The output load outputs the signals amplified by the carrier amplifier and the peaking amplifiers.

Abstract: System and method for compensating for changes in an output impedance of a power amplifier uses an impedance compensating circuit with an impedance inverter coupled to the power amplifier. The impedance inverter of the impedance compensating circuit is configured such that an output impedance of the impedance inverter is proportional to the inverse of the output impedance of the power amplifier to compensate for changes in the output impedance of the power amplifier.

Abstract: Distributed band reject filters are disclosed. A first radio frequency band reject filter is disclosed having a splitter having a first input port, a first output port and a second output port, the splitter being operable on an input signal applied to the first input port to provide a respective output signal proportional to the input signal at each of the first and second output ports, the output signals having a phase shift between 45 degrees and 135 degree with respect to the input signal, as well as first, second and third acoustic resonators coupled respectively to the first input port, the first output port and the second output port.

Abstract: A solid state power amplifier (SSPA) system may include a radio frequency (RF) input, an RF waveguide split block, multiple monolithic microwave integrated circuit (MMIC) power amplifier modules, and/or a heat spreader. The power amplifier modules and RF waveguide may be distributed about the heat spreader in different planes. Furthermore, the power amplifier modules may be located on opposite sides of the heat spreader and nonplanar to the waveguide split block. A method for dissipating heat within an SSPA may include receiving an RF signal in a first plane, amplifying the RF signal in another plane, and combining the RF signal in yet another plane.

Abstract: An apparatus and method for amplifying a transmission signals in multiple modes and multiple bands. The apparatus includes a tunable power amplifying module adapted to receive a plurality of signal types comprising multiple modes and multiple bands. The tunable power amplifying module includes a first and second power amplifier stages and a number of tunable matching networks configured to optimize an impedance value based on the mode and band of the signal to be amplified.

Abstract: The present invention relates to an integrated Doherty type amplifier arrangement and an amplifying method for such an arrangement, wherein a lumped element hybrid power divider (12) is provided for splitting input signals of main and peak amplifier stages (20, 30, 40) at predetermined phase shifts and non-equal division rates and at least one wideband lumped element artificial line (Z 1, Z2) combined with wideband compensation circuit for receiving said first amplified signal and for applying said predetermined phase shift to said first amplified signal and its higher harmonics. Thereby, the low gain of the peak amplifier is compensated by providing the non-equal power splitting at the input. Moreover, the use of the lumped element hybrid power divider leads to an improved isolation between the input ports of the main and peak amplifiers decreasing final distortions of the output signal.

Abstract: A low noise amplifier circuit including a front end voltage sensing and matching amplification circuit, a gain circuit and a combining circuit is disclosed. The front end voltage sensing and matching amplification circuit includes an input and two outputs and provides a matched signal at each output. The gain circuit includes two inputs, each input being respectively coupled to at least one of the two outputs of the front end voltage sensing and matching amplification circuit. The gain circuit further includes two outputs and an output signal is provided at each output of the gain circuit. The combining circuit combines the two output signals of the gain circuit. The combining circuit includes two inputs, each input is respectively coupled to at least one of the two outputs of the gain circuit. The combining circuit further includes an output providing a combined signal.

Abstract: A device with shared power amplifiers for use in a wireless telecommunication System. A plurality of input signals are tapered to alter the phase and/or amplitude distribution between the signals and are then distributed over the input ports of a plurality of power amplifiers. Power amplified replicas of the plurality of input signals are recreated at the output ports of the power amplifiers. The power amplified replicas of the signals are reverse tapered at an output of the device.

Abstract: A splitter circuit improves isolation between output ports. The splitter circuit comprises input port 1, output port 2, output port 3, FET 6, FET 11 and an impedance circuit. FET 6 is provided between input port 1 and output port 2 and adapted to amplify a signal at input port 1 to output an amplified signal to output port 2. FET 11 is provided between the input port 1 and the output port 3 and adapted to amplify a signal at input port 1 to output an amplified signal to the output port 3. The impedance circuit couples the output ports 2 and 3, and includes a first series circuit including inductor 15 and diode 17, series connected to each other, a second series circuit including inductor 16 and diode 18, series connected to each other, and resistor 19. The first series circuit has one end connected to output port 2 and the second series circuit has one end connected to output port 3. The resistor is connected between the other ends of the first and second series circuits and the ground.

Abstract: A power amplifier (power amplifier) having multiple solid state sub-amplifiers connected in parallel between the power amplifier input and the power amplifier output are described. The signal input to the power amplifier is provided to an RF splitter connected between the power amplifier input connector and the input of each of the sub-amplifiers. The RF splitter splits the input power from the signal input and provides the power to the sub-amplifier inputs through input electrical paths. The input electrical paths from the power amplifier input to the sub-amplifiers are substantially physically identical. Each of the sub-amplifiers drive an input of an RF combiner connected between the outputs of the sub-amplifiers and the output of the power amplifier. The RF combiner combines the output power from each of the sub-amplifiers through output electrical paths, and provides the combined power to the power amplifier output.

Abstract: The present invention relates to the field of electronic devices known as baluns. It concerns an active balun which is broadband and reciprocal. Embodiments of the invention integrate an active splitter balun with an active combiner balun so as to form three transmission lines. A first active coupling is provided between the first and second transmission lines and a second active coupling is provided between the first and third transmission lines. The active couplings are provided by means of amplifier cells distributed along the transmission lines. Embodiments of the invention have configurable means for polarizing the different amplifier cells so as to create a specific coupling direction between the various transmission lines. The device according to the invention can be applied in the field of broadband mixers which are used, notably, in radio transmission and reception circuits.

Abstract: A differential amplifier comprises terminals for receiving signals, and outputting a signal, and differential pairs, each having an input and output pair, the differential pairs supplied with currents, respectively, a load circuit connected to the differential pairs, an amplifier stage for receiving input, a signal of at least one connection node of the load circuit and output pairs of the differential pairs, the amplifier stage having an output connected to a terminal and a connection switching circuit for controlling switching between connection states of a first differential pair and second differential pair.

Abstract: The present invention discloses a premium power amplifier applied in an antenna module, and the premium power amplifier includes a first transmission unit, having two symmetrical and identical first arc-shaped circuits, two secondary power amplifiers connected in parallel with each other, and a second transmission unit having two symmetrical and identical second arc-shaped circuits, in which those components above are installed between a power amplifier and an output terminal of the antenna. So that the output power of the antenna can be improved greatly, and the effective transmission distance can be extended.

Abstract: Parasitic coupling effects between RF or microwave transistors provided in a common package are compensated by connecting one or more capacitors between the transistors. By connecting the capacitor(s) at a location that corresponds to the site of the coupling, the compensation is effective over a wide frequency band. This coupling-compensation makes it feasible to provide, in a common package, RF or microwave transistors intended to operate in quadrature, thereby improving performance matching and operating efficiency of the overall device.

Abstract: A travelling wave amplifier has two inductive transmission lines (12,14) with a plurality of amplifier devices (10) connected between them. At least one of the transmission lines (14) further comprises a plurality of delay elements (50), each delay element being provided in series between a respective pair of inductive elements. The delay elements enable the pulse propagation speeds in the two transmission lines to be matched while leaving freedom in the selection of impedance values to provide input and output impedance matching of the amplifier. In this way, even when the individual amplifier devices (10) have unequal input and output impedances, the amplifier can be configured to provide matched input and output impedances as well as matched propagation speeds.

Abstract: A transmit signal generated by the baseband processor in a translational loop type RF transmitter is “pre-distorted” so as to counter act magnitude distortion and group delay variation imposed by a narrow PLL signal filter. The pre-distortion occurs in two steps: a magnitude equalizer in the baseband processor pre-distorts the amplitude of the transmit signal according to the inverse of the PLL signal filter magnitude response, and a group delay equalizer linearizes the phase response of the entire transmitter chain, i.e., pre-distorts the transmit signal such that the combined phase response of magnitude equalizer, group delay equalizer, and PLL signal filter is linear. With such pre-distortion, a loop filter is provided for with component values that define a relatively small bandwidth for the loop filter to filter spurious tones that result from an IF reference feedthrough to a voltage controlled oscillator of the translational loop.

Abstract: A predistortion linearization device (D) produces gain and phase expansions making it possible to compensate for the gain compression and phase variation of a power amplifier. This device (D) also allows the conventional adjustment of amplitude, the adjustment of the form of the gain and phase expansions as a function of a microwave input signal (Se).

Abstract: An amplifier that amplifies an input signal and provides the amplified signal to a load at a summing junction that has a first impedance value. The amplifier includes a splitter network receiving the input signal and providing a phase delayed signal and an undelayed signal; a carrier amplifier path amplifying the phase delayed signal and including a carrier amplifier and a first output match network coupled between the carrier amplifier and the summing node; and a peaking amplifier path amplifying the undelayed signal and including a peaking amplifier, a second output match network coupled to the peaking amplifier, and a phase delay element coupled between the second output match network and the summing node, wherein the phase delay element provides a degree of phase delay and has a designed characteristic impedance value that is larger than the first impedance value for increasing the off-state impedance of the peaking amplifier.

Abstract: A system for controlling a power supplied to a load from a radio frequency amplifier system includes a radio frequency signal generator adapted for generating a radio frequency signal, an amplifier to which the radio frequency signal is supplied and that amplifies the radio frequency signal into a radio frequency power signal, a power coupler connected to the amplifying member for coupling the radio frequency power signals, where the power coupler includes a summing connection adapted for connection to the load and a compensating connection adapted for connection to a dissipative element. A first control value generating member is adapted for receiving a signal proportional to a power output from the power coupler at the summing connection and is adapted for generating a first control signal for controlling the amplifier or a current supply that supplies current to the amplifier.

Abstract: Microwave coupling network comprising a passive resistive pi net and a coupling capacitor is coupled to a branching point. The branching point is coupling to respectively a plurality of common drain FET amplifier stages or respectively to common collector BJT amplifier stages, wherein respectively the source, or respectively the emitter, is coupled to at least one output port.

Abstract: Disclosed herein is a power amplifier using a power combiner, which is capable of minimizing power loss and improving efficiency of the power amplifier with a large output power, by combining powers generated by a plurality of power amplifiers used in a wireless communication system using a transmission line transformer.

Abstract: An amplifier has an input port, an output port, N gain elements in parallel, an input power splitter coupled between the input port of the amplifier and the input ports of the N gain elements, an output resistor chain extending between the output ports of the first through Nth gain elements, and an output power combiner coupled between the output ports of the N gain elements and the output port of the amplifier. The output power combiner presents a corresponding input impedance to each of the N gain elements. At least two of the input impedances presented by the output power combiner to the N gain elements are substantially different from each other.

Abstract: Apparatus and method for reducing the current consumption and increasing the efficiency of an RF power amplifier (PA), according to which the load, connected to the output stage of the PA, tuned dynamically or statically for each level of the desired output power. By doing so, the output impedance of the output stage is essentially matched, such that the dynamic RF load line has a slope that corresponds to the impedance required to provide this level. Whenever a smaller output power is desired in response to reduction in the input signal to the amplifier, the load is further tuned, such that the dynamic or static RF load line has a slope that causes the power amplifier to essentially remain in saturation at the smaller output power.

Abstract: An electronic device where the ratio between two amplification factors of two amplifiers, called main amplifiers, is adjusted using a control means. The control means constantly equalizes the output signals of the two main amplifiers by adapting one of the control signals. The output signals are acted on in order to adjust the control signals. Owing to the fact that the input signals are in a ratio N, this same ratio is obtained between the amplification factors of the two main amplifiers. The two main control signals, used to control the main amplifiers, are employed for controlling any other amplification factor of at least two other amplifiers or groups of amplifiers, so as to establish a ratio N between these other amplification factors. The main circuit thus allows N to be applied and regulated between the amplification factors of other amplifiers.

Abstract: An embodiment of the present invention provides an apparatus, comprising a power amplifier with a tunable impedance matching circuit including a plurality of tunable dielectric varactors and a DC voltage source interface capable of providing voltage to said plurality of saud tunable dielectric varactors.

Abstract: There is provided a matching circuit, in which a main-matching block and a sub-matching block are connected in series. The sub-matching block includes: a series matching block of which one end is connected to the main-matching block; and a parallel matching network connected to the other end of the series matching block. At a first frequency f1, the connection point of the series matching block and a first parallel matching block is caused to be in an open state for a radio-frequency signal, and the connection point of the first parallel matching block and the second parallel matching block is caused to be in a short state for the radio-frequency signal. Impedance matching is performed by the main-matching block and the series matching block at the first frequency f1, and is performed by the main-matching block and the sub-matching block at the second frequency f2.

Abstract: A matching circuit includes a demultiplexer for demultiplexing a signal outputted from an amplification device into signals of respective frequency bands, and at least two matching blocks which are connected to the demultiplexer, are respectively fed with the signals of the respective frequency bands, and perform impedance matching in the respective frequency bands of the inputted signals. Impedance matching is performed on each of the demultiplexed signals of the respective frequency bands, thereby achieving a matching circuit capable of efficiently performing impedance matching in the respective frequency bands. With this matching circuit, it is possible to achieve a multi-band amplifier capable of simultaneously amplifying signals of multiple frequency bands with high efficiency and low noise.

Abstract: An amplifier has a main amplifier circuit with multiple amplification stages, including a driving stage and an auxiliary amplifier circuit with multiple amplification stages, including a driving stage. A splitter circuit splits an input signal to provide path asymmetry in splitting the input signal between the main amplifier path and auxiliary amplifier path. The driving stage of the auxiliary amplifier circuit has a power rating higher than the power rating of the driving stage of the main amplifier circuit to provide a gain asymmetry in the amplifier circuit paths.

Abstract: It is an object of this invention to provide a high-frequency amplifier which can efficiently amplify an input signal in a plurality of different frequency bands in a simple configuration. The high-frequency amplifier is configured such that an RF signal having n frequencies (f1>f2 . . . >fn) applied to the amplifier is converted by an impedance conversion circuit to a higher impedance than the output impedance of the amplifier, and is branched into the highest frequency f1 and lower frequencies lower than that by a high-pass filter and a low-pass filter. Frequency f1 passes high-pass filter 31, and is thereby converted to 50 ohms. The frequencies lower than frequency f1 filtered by the low-pass filter are converted to a high impedance by an impedance conversion circuit, and are branched into the second highest frequency f2 and lower frequencies by high-pass filter 32 and low-pass filter 42.

Abstract: A traveling-wave amplifier includes amplifiers coupled anti-parallel to transmission lines. Phase(s) of the amplifiers provide phase matching, which may additionally or alternately be provided by couplers or spatial offset of the amplifiers and couplers. The traveling-wave amplifier provides compensation for the losses of the transmission lines, amplification of the signals and isolation between input and output by coupling the amplifiers to the transmission lines anti-parallel.

Abstract: A Doherty amplifier is described which comprises: a power splitter (120) having a first output and a second output, wherein the first output is connected to a main power splitter (392) having first and second outputs which differ in phase by 90°; and the second output is connected to an auxiliary power splitter (342) having first and second outputs which differ in phase by 90°; a main final stage amplifier (234) comprising first (324) and second (325) main paired amplifiers, the inputs of which are connected to the first and second outputs of the main power splitter (352); an auxiliary final stage amplifier (244) comprising first (344) and second auxiliary (345) paired amplifiers, the inputs of which are connected to the first and second outputs of the auxiliary power splitter (342); wherein the output from the first main paired amplifier (334) is connected to the output from the first auxiliary paired amplifier (344) by an impedance inverter (250); and the output from the second main paired amplifier (345) i

Abstract: A transceiver is provided that includes a TX path mixer that up converts, a RX path mixer that down converts, and a local oscillator that provides a mixing frequency for the TX and RX mixers. The transceiver further provides a directional coupler having an input path coupled to the input of a UHF VCO for dividing power to a TX path and a RX path in the directional coupler. A mixer is provided to mix the input/output frequencies from the RX IF/TX IF. The operating frequency range of the directional coupler is greater than the output frequency of the UHF VCO. The directional coupler splits the UHF VCO unequal power at different ports of the directional coupler to redistribute the power in different ports, thus preventing the TX signal from being reflected back to the RX signal. The invention further provides the additional isolation required by the TX local oscillator chain by preventing reverse power feed into the RX local oscillator.

Abstract: A transmitter-combining broadcast system and method is provided that allows IBOC-compatible broadcast with simple analog-to-IBOC upgradeability with high efficiency. At full power, a standard analog signal and an IBOC-compatible digital signal are transmitted by combining the output of a wide-band transmitter containing VHF-FM analog and in-band digital signals with the output of a second transmitter containing VHF-FM analog alone. By shifting signal phase, two analog signals can be combined with low loss, and net power waste can be reduced by at least 80%. The approach enables full IBOC upgradeability for existing analog-only systems, including reuse of existing transmitting equipment. Full IBOC compliance is supported, including during operation with reduced power. Switchover between partial and full power operating modes can be performed without full system shutdown.

Abstract: Amplifier apparatus comprising a power amplifier (4) having an operating frequency in the radio frequency (‘RF’) or microwave or higher ranges and a pre-distorter (2), the characteristics of the power amplifier (4) comprising a distortion from a linear transfer function. The pre-distorter (2) comprises a non-linear path (7), a linear path (8), input means (6) responsive to an amplifier input signal for applying respective prre-distorter input signals to the paths (7,8) and combining means (13) for combining a linear signal from the linear path (8) with a non-linear signal from the non-linear path (7) to produce a pre-distorted signal. The characteristics of the pre-distorter (2) comprise a distortion relative to a linear transfer function such as to tend to compensate for the distortion of the transfer function of the power amplifier.

Abstract: A power amplifier apparatus that includes a main power amplifier circuit and an injection power amplifier circuit is provided. The main amplifier includes a pair of quadrature coupled amplifiers. Similarly, the injection power amplifier also includes pair of quadrature coupled amplifiers. The output signal from the injection amplifier is connected to the isolation port of the quadrature coupler of the main amplifier. The input signal is split and applied to the inputs of both the main and injection amplifiers. The gain and phase through the injection amplifier is adjusted in order to vary the magnitude and phase of the signal injected into the isolation port of the quadrature combiner of the main amplifier. By varying the magnitude and phase of the injected signal, the impedance seen by the individual amplifiers within main amplifier can be controlled. Controlling these impedances allows the properties of the main amplifier to be dynamically varied.

Abstract: An amplifier device (40) includes at least one amplifier (42) having an output. A plurality of conductors (48, 50, 52) are coupled to the output in parallel with each other. The plurality of conductors (48, 50, 52) each has an electrical length that corresponds to a quarter wavelength of a signal amplified by the amplifier. The electrical length of the conductors (48, 50, 52) allows for any one of them to be selectively shorted so that the shorted conductor appears as an open circuit relative to the output of the amplifier (42) and has no effect on the operation of the amplifier device under such circumstances. The disclosed amplifier configuration allows for daisy chain connections for stacking amplifiers to increase amplification in an effectively lossless manner.

Abstract: Coupler-based amplifiers provide a measure of load mismatch based on the difference between the two output signal amplitudes from the amplifiers. This measure can be used to control variable matching networks (VMNs) or amplifier supply voltages to maintain constant distortion levels and high power transfer/efficiency and even to control output power. Load mismatch is measured by comparing the amplifier device output amplitudes and adjusting the circuit based on the comparison to counteract undesired behavior, such as increasing distortion levels.

Abstract: A system and method for a distribution network is provided wherein cascaded power amplifiers with bypass switching are disposed along the branches of the network. The amplifiers may have an RF modem and a programmable digital computer that enables communication with a headend or a controlling computer as well as a bypass switch control for disabling the amplification function of the amplifiers. The amplifier may have a wireless communication system for communicating with individual subscriber's homes and communicating with a neighboring amplifier system for use in emergency situations or during installation and configuration of the network. The network comprised of the amplifiers may have redundant signal paths, using the wireless communication devices of the amplifiers, which may be used as backup signal paths for certain communications requiring high uptime such as telephony.

Abstract: While a switch SW4 is connected to “a”-terminal side, offset of a differential output voltage “A?” of a D/A converter 500a (500b) is held in a comparator 400, and is reflected to a reference voltage. Thereafter, the switch SW4 is switched to a “b”-terminal side, and offset of a differential output voltage “A+” of the D/A converter 500a (500b) is measured by the comparator 400. An error signal is outputted to a counter 412 so as to count up the counter 412. Such an operation is repeatedly carried out in which the count value is added to 1.7 V and then the added count value is inputted into the D/A converter 500a (500b), and such a count value latched in a latch at timing when the error signal is inverted is defined as an offset correction value.

Abstract: A high power Doherty amplifier circuit having at least one input terminal and at least one output terminal comprising at least one carrier transistor (30) forming a main amplifier stage; at least one peak transistor (32) forming a peak amplifier stage; a first input line (27) connecting the input terminal (28) to an input (29) of the carrier transistor (30); a second input line (31) connecting the input terminal (28) to an input (63) of the peak transistor (32); a first output line (33) connecting the output terminal (56) to an output (49) of the carrier transistor (30); and a second output line (35) connecting the output terminal (56) to an output (75) of the peak transistor (32).

Abstract: An amplifier includes a main amplifier circuit and at least one auxiliary amplifier circuit. Portions of an RF signal to be amplified are delivered to the main and auxiliary amplifiers. The auxiliary amplifier circuit is selectively operable to operate in combination with the main amplifier circuit, such as based on the level of the RF signal. At least one hybrid coupler circuit has input ports coupled with outputs of the main amplifier circuit and auxiliary amplifier circuit. The hybrid coupler circuit is operable to combine amplifier circuit output signals at a coupler first output port. A coupler second output port is terminated with one of an electrical short and an electrical open circuit.

Abstract: A re-circulating amplifier comprising a SAW filter with group delay characteristics for providing a time delay function.

Abstract: A system for amplifying a signal is provided. The system includes a wave guide and an active loop amplifier disposed in the wave guide. The active loop amplifier receives the signal and generates a magnetic field in response to the signal, such as one that couples to the propagating mode of the wave guide.

Abstract: An amplifier includes a main amplifier circuit and at least one auxiliary amplifier circuit. Portions of an RF signal to be amplified are delivered to the main and auxiliary amplifiers. The auxiliary amplifier circuit is selectively operable to operate in combination with the main amplifier circuit, such as based on the level of the RF signal. At least one hybrid coupler circuit has input ports coupled with outputs of the main amplifier circuit and auxiliary amplifier circuit. The hybrid coupler circuit is operable to combine amplifier circuit output signals at a coupler first output port. A coupler second output port is terminated with one of an electrical short and an electrical open circuit.

Abstract: Output amplifier stage (1) of a high frequency generator (1) with tube (2) operating in class B or C has its output (5) looped back on the input (4) by means of a coaxial line (31) with a length equal to approximately the wave length corresponding to the operating frequency. The apparent gain of the amplifier stage (1) is thus increased and the output power from an intermediate amplifier (24) can be correspondingly reduced, amplifying a stable signal at the operating frequency.

Abstract: A divider 3 for dividing and distributing a high-frequency signal input from an input terminal 1 to two output sides, a main amplifying unit 4, connected to one output side of the divider 3, for amplifying one high-frequency signal output from the divider 3, a subsidiary amplifying unit 5, connected to the other output side of the divider 3, for performing no operation in case of a low instantaneous electric power of the other high-frequency signal output from the divider 3 and amplifying the other high-frequency signal in case of a high instantaneous electric power of the other high-frequency signal and a circulator 6 for injecting the high-frequency signal amplified in the subsidiary amplifying unit 5 into the output side of the main amplifying unit 4 and injecting the high-frequency signal amplified in the main amplifying unit 4 into an output terminal 2 are arranged.

Abstract: A predistortion circuit for a microwave amplifier and more particularly to predistortion circuit configured as a Doherty amplifier. The predistortion circuit is adapted to be coupled to a downstream Doherty amplifier to precompensate for the gain compression and phase expansion of the downstream Doherty amplifier as the input power level is increased while simultaneously reducing the intermodulation (IM) distortion. In order to provide precompensation, the precompensation circuit is operated at bias level to provide gain expansion and phase compression to cancel out the gain compression and phase expansion of the downstream Doherty amplifier to provide a higher overall linear power added efficiency (PAE).

Abstract: It is difficult that the impedance of the circuit part on the output side of an amplifying element at the frequency of a modulating wave is lower, and consequently, it is difficult to more effectively use the linearity of the amplifying element. The phase of a signal of the frequency of the modulating wave included in an amplified signal output from a FET is inverted by a difference frequency inverting circuit. The inverted signal of the frequency of the modulating wave and a signal of the frequency of a modulated wave included in an amplified signal output from a FET cancel each other out at the drain of the FET. At the drain end of the FET, the signal of the frequency of the modulating wave included in the amplified signal of the FET and a signal of the frequency of the modulating wave output from the FET cancel each other out.

Abstract: A hybrid coupler (66, 67; 72, 73) has four ports and is capable of coupling radio frequency signals having a certain frequency from at least one port to at least one other port. The hybrid coupler (66, 67; 72, 73) is implemented as a differential coupler arranged to couple differential radio frequency signals. With such a hybrid coupler a power amplifying circuit can be produced which has sufficiently low ripple on the supply voltage to be integrated together with more sensitive radio circuits, and which is also insensitive to load mismatch such that an isolator can be avoided. A differential hybrid coupler allows the output current to be shared between four transistors or amplifiers, thus reducing the amplitude of the ripple. Further, the frequency of the ripple is four times the operating frequency of the circuit, which makes it much easier to filter out the ripple.