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 finite impulse response (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 −2 to +0.5 dB across the 0.25-2 GHz frequency range while consuming 2.3–15.7 mW of power. It achieves an HR ratio (HRR) of
$>$
46/48 dB with
$>$
+8/+11 dBm third/ fifth-order harmonic blocker P1dB.