Research And Design Of Programmable Gain Amplifier With I/Q Mismatch Calibration

The multi-modulus RF receiver consists of a low noise RF amplifier,mixer, frequency synthesizer, programmable gain amplifier, low pass filter,standard SPI etc.. At some circumstance, high image rejection ratio isrequired. So the I/Q mismatch calibration is a critical module for the receiver.In the same time, the variable gain amplifier is one of the key modules in thechip. It works with the automatic gain control (AGC) circuit to provideconstant signal power for the ADC. In this paper, a programmable gainamplifier with I/Q mismatch calibration is proposed. The programmable gainamplifier consists of two gain stage and programmable resistors are used toprovide I/Q mismatch calibration.In this paper, a two stage closed loop amplifier is designed. The gainrange is from6dB to30dB and the tunable precision is6dB a step. Thecompensation precision is0.1dB for the I/Q gain mismatch and0.5degree forthe I/Q phase mismatch. To reduce the power consumption, the bias current istunable at different process corners for the reason that the operation amplifiershould have enough bandwidth.Firstly, the basic theory of the general communication system is presented.And we learned about different kinds of the variable gain amplifier. Secondly,we illustrated the structure of the multi-modulus RF receiver and introducedthe system index of the chip. Finally, a programmable gain amplifier isdesigned, as well as the I/Q mismatch calibration, DC offset compensation,constant gm bias circuit and low noise precision voltage reference circuit.