A channel selection filter for a WCDMA direct conversion receiver

A channel selection filter for a WCDMA direct conversion receiver is described. The 5th order Chebyshev low-pass filter with a 0.01dB ripple has the -3dB frequency close to 2MHz. The circuit uses two on-chip high-pass filters for offset compensation. The real pole of the prototype is realized with a passive RC element which is the first stage in the filter. The filter achieves +25dBV out-of-band IIP3, + 77dBV out-of-band IIP2 and 9.4nV/√Hz input-referred noise density. The maximum gain is 67.7dB and the circuit draws 4.3mA from a 2.7V supply.