Variable Gain Complex Active RC Bandpass Filter With Image Rejection

This paper presents a low power, high image-rejection, and linear variable gain control, high gain IF band-pass filter. It's a complex filter, without the image band-pass, can provide 50dB image-rejection. Using a digital gain control circuit, the filter achieves 23～55dB gain, 1dB/Step linear gain control. And a frequency compensate circuit is using for compensation the effect of process and temperature variations. It has been fabricated by 0.18um CMOS process, 0.45 mm~2 die size, 5mW power consumption, and achieve 55dB max gain, 0.6dB pass-band ripple, -14dbm IIP3.