A 4^th-order low-power diode-C-based filter with 12dBm-IIP3 at the cut-off frequency

Abstract

This paper presents a 4th-order low-pass continuous-time filter with 21.4 MHz bandwidth. Using a positivefeedback in combination with resistors, this architecture synthesizes two complex conjugate poles. The filter is designed and optimized to feature high-linearity along all filter passband, and, in particular, at the cut-off frequency edge. The filter consumes only 100 µA with 1.8 V voltage supply, and achieves 45 µW/pole power consumption, 300 µVRMS input-referred noise, 21.9 dBm IIP3 with 2-3 MHz input tones and 12 dBm IIP3 near the cut frequency using 19-20 MHz tones.