A compensation circuit of a power amplifier includes a varactor, a voltage sensor and a control circuit. The varactor is coupled to an input terminal of the power amplifier. The voltage sensor is arranged for detecting an amplitude of an input signal of the power amplifier to generate a detecting result. The control circuit is coupled to the varactor and the voltage sensor, and is arranged for controlling a bias voltage of the varactor to adjust a capacitance of the varactor according to the detecting result.

A compensation circuit of a power amplifier includes a varactor, a voltage sensor and a control circuit. The varactor is coupled to an input terminal of the power amplifier. The voltage sensor is arranged for detecting an amplitude of an input signal of the power amplifier to generate a detecting result. The control circuit is coupled to the varactor and the voltage sensor, and is arranged for controlling a bias voltage of the varactor to adjust a capacitance of the varactor according to the detecting result.

A method and apparatus for linearizing a baseband filter are provided. The apparatus is configured to, via a first conducting module, receive a first current signal. The apparatus is further configured to, via a converting module, receive a second current signal, generate a voltage signal based on the second current signal, and apply the voltage signal to the first conducting module. An amount of the second current signal received by the converting module is based on an amount of the first current signal flowing through the first conducting module. The apparatus is also configured to, via a second conducting module, control an output current signal based on the voltage signal. The output current signal is controlled to be a linear replica of the first current signal for in-band frequencies.

A method and apparatus for linearizing a baseband filter are provided. The apparatus is configured to, via a first conducting module, receive a first current signal. The apparatus is further configured to, via a converting module, receive a second current signal, generate a voltage signal based on the second current signal, and apply the voltage signal to the first conducting module. An amount of the second current signal received by the converting module is based on an amount of the first current signal flowing through the first conducting module. The apparatus is also configured to, via a second conducting module, control an output current signal based on the voltage signal. The output current signal is controlled to be a linear replica of the first current signal for in-band frequencies.

An apparatus for PLL bandwidth expansion including a compensation filter and a phase locked loop, where the compensation filter is programmed with a compensation function derived based on programmable coefficients and parameters of a transmitting device, a frequency response of the phase locked loop, and a wanted frequency response.

An apparatus for PLL bandwidth expansion including a compensation filter and a phase locked loop, where the compensation filter is programmed with a compensation function derived based on programmable coefficients and parameters of a transmitting device, a frequency response of the phase locked loop, and a wanted frequency response.