An integrated circuit RF power amplifier that includes a substrate; a low power (LP) amplifier; a high-power (HP) amplifier; and an asymmetrical parallel-combining transformer. The substrate is configured to supports the LP amplifier, the HP amplifier and the asymmetrical parallel-combining transformer. The LP amplifier is configured to amplify a LP RF input signal to provide a LP amplified signal. The HP amplifier is configured to amplify a HP RF input signal to provide a HP amplified signal. The HP amplified signal has maximal intensity that exceeds a maximal intensity of the LP amplified signal. The wherein the asymmetrical parallel-combining transformer may include (a) a HP primary winding that is constructed and arranged to receive the HP amplified signal; (b) LP primary windings that are constructed and arranged to receive the LP amplified signal; and (c) secondary windings that are magnetically coupled to the HP primary winding and to the LP primary windings, and are constructed and arranged to output a output signal.

An RF transmitter with a power combiner and a differential amplifier is provided. The power combiner converts a differential output signal to a single-end output signal and transmits the single-end output signal to the antenna. The differential amplifier includes common-source input transistors, common-gate output transistors and a switch module. The common-source input transistors amplify a differential input signal and output an amplified differential signal. The common-gate output transistors, including sources electrically coupled to the common-source input transistors and drains electrically coupled to the power combiner, generate the differential output signal according to the amplified differential signal. The switch module is electrically coupled between the gates. The switch module electrically couples the gates of the common-gate output transistors if the RF transmitter is in operation and electrically isolates the gates if the RF receiver is in operation.

An RF transmitter with a power combiner and a differential amplifier is provided. The power combiner converts a differential output signal to a single-end output signal and transmits the single-end output signal to the antenna. The differential amplifier includes common-source input transistors, common-gate output transistors and a switch module. The common-source input transistors amplify a differential input signal and output an amplified differential signal. The common-gate output transistors, including sources electrically coupled to the common-source input transistors and drains electrically coupled to the power combiner, generate the differential output signal according to the amplified differential signal. The switch module is electrically coupled between the gates. The switch module electrically couples the gates of the common-gate output transistors if the RF transmitter is in operation and electrically isolates the gates if the RF receiver is in operation.

The present invention provides a class AB amplifier, wherein the class AB amplifier includes a cascode stage with a filter and an output stage. The cascode stage with the filter is arranged for receiving an input signal to generate a first driving signal and a second driving signal, wherein the filter filters the input signal to generate an filtered input signal, and at least one of the first driving signal and the second driving signal is generated according to the filtered input signal. The output stage is coupled to the cascode stage, and is arranged for generating an output signal according to the first driving signal and the second driving signal.

A radio frequency transmitter includes a digital power amplifier and a bias control circuit. The digital power amplifier is arranged for receiving at least a radio frequency input signal, a digital amplitude control word signal and at least one bias voltage to generate a radio frequency output signal. The bias control circuit is coupled to the digital power amplifier, and is arranged for adjusting the at least one bias voltage according to a power control signal.