Realization of Low-Loss Fully-Passive Harmonic Rejection N-Path Filters

This work presents a low-loss fully-passive harmonic rejection (HR) N-path filter that performs FIR filtering within its core by sequentially charging the baseband capacitors and exploiting combined charge sharing and capacitor stacking techniques. The proposed HR N-path filter achieves an in-band (IB) gain of -2dB to +0.5dB across the 0.25-2GHz frequency range while consuming 2.3-15.7mW of power. It achieves a harmonic rejection ratio (HRR) of >46/48dB with >+8/+11dBm 3rd/5th order harmonic blocker P1dB.