An apparatus is disclosed for providing a common mode voltage to the inputs of a first differential amplifier (404, R3, R4) which outputs the difference between two signals. A second differential amplifier (406, R9, R10) receives the output of the first differential amplifier (404, R3, R4), and the output of the second differential amplifier (406, R9, R10) is fed back to the inputs of the first differential amplifier (404, R3, R4) as a common mode voltage. Since both inputs of the first differential amplifier (404, R3, R4) receive the fed back common mode voltage, the first differential amplifier (404, R3, R4) still outputs only the difference in the two signals, but the presence of the common mode voltage allows the first differential amplifier (404, R3, R4) to operate with lower noise if the voltage levels of the inputs to the first differential amplifier (404, R3, R4) vary. The second differential amplifier (406, R9, R10) may be of significantly lower quality and cost than the first differential amplifier (404, R3, R4), without affecting the performance of the first differential amplifier (404, R3, R4).

An embodiment of an amplifier includes N (N>1) switch-mode power amplifier (SMPA) branches. Each SMPA branch includes two drive signal inputs and one SMPA branch output. A module coupled to the amplifier samples an input RF signal, and produces combinations of drive signals based on the samples. When an SMPA branch receives a first combination of drive signals, it produces an output signal at a first voltage level. Conversely, when the SMPA branch receives a different second combination of drive signals, it produces the output signal at a different second voltage level. Finally, when the SMPA branch receives a different third combination of drive signals, it produces the output signal at a voltage level of substantially zero. A combiner combines the output signals from all of the SMPA branches to produce a combined output signal that may have, at any given time, one of 2*N +1 quantization states.

A Doherty amplifier is disclosed, being adapted to receive an RF input signal and to output an RF output signal and comprising a main amplifier and a peak amplifier, each comprising: a first amplifier (T1, T1') and a second amplifier (T2, T2'), each amplifier having a respective input terminal and a respective output terminal, the first amplifier and the second amplifier being adapted to amplify a respective input signal derived from the RF input signal and received at the respective input terminal and to deliver a first output signal and a second output signal, respectively; a first phase shifter (14, 14') and a second phase shifter (15, 15') coupled to the output terminal of the first amplifier and to the output terminal of the second amplifier, respectively; a third phase shifter (16, 16'); and a fourth phase shifter (17, 17').

A power amplification circuit includes two identical and independent power amplifiers (22) and a balance/unbalance (24) converter. The balance/unbalance converter has a balanced terminal for inputting two signals with opposite phases and an unbalanced terminal for outputting a converted signal. The balanced terminal includes a first balanced pin and a second balanced pin to which two signals with opposite phases are applied. Furthermore, the input pins of the two power amplifiers are separately connected to the balanced output pins (211,212) of an RFIC (21) to independently amplify the power of the output signal on the balanced output terminal of the RFIC, and then the output pins of the amplifiers are connected to the first balanced pin and second balanced pin of the Balun. Therefore, the power of the output signal transmitted on the unbalanced terminal is multiplied by two.

Double transformer balun for maximum PA (Power Amplifier) power. A novel approach is presented herein by which conversion from a differential signal to single-ended signal may be achieved using a double transformer balun design. The secondary coils of the double transformer balun also operate as a choke for the PA supply voltage. The secondary coils can operate as an RF (Radio Frequency) trap or choke to keep any AC (Alternating Current) signal components and to pass any DC (Direct Current) components. By using a double transformer balun design, relatively thinner tracks may be employed thereby ensuring a high degree of electromagnetic coupling efficiency and high performance. Also, these relatively thinner tracks consume a relatively small amount of space on the die. The double transformer balun design also includes a matching Z (impedance) block that is operable to math the Z of an antenna or line that the PA is driving.

First and second inductors (2,3) are formed in an identical plane of a substrate (10) as thin films each having a spiral shape, and are concentrically arranged and electromagnetically coupled. The collector of an amplifying transistor (1) and a collector voltage terminal (6) are connected to the two ends of the first inductor (2), respectively. An unbalanced oscillation signal is input to the base of the amplifying transistor (1). An oscillation signal output from the collector of the amplifying transistor (1) is transmitted to the first inductor (2), and is tuned and coupled by the second inductor (3). Consequently, a balanced pair of oscillation signals are output from output terminals at the two ends of the second inductor (3).

A radio frequency circuit and a method of supplying power to a circuit block are described. The circuit (200) comprises a circuit block (202) comprising a transformer (230); and at least two inductors (250, 252) for supplying current from a power supply to the circuit block.

POWER CONTROLLABLE WIRELESS COMMUNICATION DEVICE

A power controllable wireless communication device MOD includes a variable gain amplifier PGA having a gain that can be controlled based on a gain control signal, a reference power generation circuit RPG, which generates first reference power and second reference power differing from the first reference power, a sensor circuit SCC supplied with selectively power of a high frequency signal output from the variable gain amplifier PGA, and the first reference power and the second reference power generated by the reference power generation circuit RPG, and a control circuit which generates the gain control signal based on a sensor output from the sensor circuit. When controlling power, the control circuit generates the gain control signal based on ratios among a first sensor output corresponding to the first reference power, a second sensor output corresponding to the second reference power, and a high frequency sensor output corresponding to the power of the high frequency signal.

An RF circuit for wireless devices comprises a single differential power amplifier and an impedance balancing circuit for each frequency band. The impedance balancing circuit serves both to provide an appropriate impedance at the output of the amplifier as the operating mode of the device changes, and also transforms the differential output of the amplifier to a single-ended output. The impedance balancing circuit optionally comprises a BALUN circuit and a variable capacitor that is varied as the operating mode changes in order to vary the impedance at the output of the amplifier.