Breaking the Performance Tradeoffs in N-Path Mixer-First Receivers Using a Second-Order Baseband Noise-Canceling TIA

Abstract

Input-match, noise figure (NF), in-band (IB) third-order input-referred intercept point (IIP3), out-of-band (OB) IIP3, and power consumption are five crucial performance metrics of a radio frequency (RF) receiver. In a typical passive mixer-first receiver, these five performance metrics are tightly coupled with each other. In this article, a second-order baseband noise-canceling (NC) scheme is proposed to break the performance tradeoffs in an N-path mixer-first receiver. Analytical expressions for input impedance, NF, IB-IIP3, and OB-IIP3 of the proposed NC receiver are derived and verified. A prototype mixer-first receiver is implemented in CMOS 180 nm technology and tested in the laboratory. In measurements, the receiver achieves an NF less than 4 dB and IB-IIP3 of +14.5 dBm over a frequency range of 0.2–1.2 GHz. The measured OB-IIP3 is +25 dBm at a frequency offset of 2.2 times the bandwidth while consuming a static power of 20 mW.