A 2.7-dB NF 55-dBm IIP2 Blocker-Tolerant Receiver Front End Employing Dual RF and BB <i>N</i>-Path Filters for 5G New Radio Cellular Applications

In this article, a low-noise and high input-referred second-order intercept point (IIP2) blocker-tolerant receiver (RX) front end utilizing dual radio frequency (RF) and baseband (BB) N-path filters are presented for fifth-generation (5G) new radio (NR) cellular applications. The proposed RX front end significantly improves the out-of-band (OB) IIP2 and input-referred third-order intercept point (IIP3) via a dual RF and BB N-path filtering approach. An RF N-path bandpass filter (BPF) and BB N-path low-pass filter (LPF) are implemented using N-path notch feedback and feedforward (FF) BB N-path high-pass filter (HPF) configurations, respectively. The double-balanced mixer in the main signal path is reused to implement the RF N-path BPF and BB N-path LPF. It reduces the number of required switches, thereby alleviating the burden of the local oscillator (LO) chain. The RX front end comprises a transformer-based noise-canceling (TBNC) balun-low-noise amplifier (LNA), double-balanced down-conversion passive mixers driven by 25% duty-cycle LO signals, isolation resistors, trans-impedance amplifiers (TIAs), RF N-path notch feedback, and FF BB N-path HPF. Fabricated using a 65 nm CMOS process, the RX front end is primarily characterized for the mid-band (MB) of 5G NR sub-6 GHz cellular applications. It achieves a noise figure (NF) of 2.7 dB, a conversion gain of 43 dB, an OB IIP3 of 2.7 dBm, and an IIP2 of greater than 55 dBm without calibration. The total power consumption of the RX front end is 14.41 mW with a supply voltage of 1 V. Its active die area is 0.66 mm2.