A Blocker-Tolerant Receiver Front End Employing Dual-Band N-Path Balun-LNA for 5G New Radio Cellular Applications

In this article, a blocker-tolerant receiver (RX) front end employing a dual-band
$N$
-path balun low-noise amplifier (balun-LNA) is presented for advanced cellular applications. The proposed RX front end can achieve a superior input-referred second-order intercept point (IIP2) performance without any IIP2 calibration, as the
$N$
-path balun-LNA performs RF bandpass filtering and enhances blocker tolerance as well as the overall linearity of the RX. The proposed band-switchable differential inductor with a center tap enables the
LC
tank of the balun-LNA to support the operation of both low-band (LB) and mid-band (MB) frequencies for 5G new radio (NR) sub-6-GHz cellular applications. The RX front end is comprised of the dual-band
$N$
-path balun-LNA, a
$G_{m}$
-stage, current-mode passive mixers with a 25% duty-cycle local oscillator signal, current-mode passive
RC
low-pass filters, and transimpedance amplifiers. The RX front end was fabricated through a 65-nm CMOS process, and it was characterized primarily in the 5G NR LB and MB frequencies. The active die area was 2.24 mm
²
, and the RX front end drew a bias current of 15.1 mA from a nominal supply voltage of 1 V. It achieved a noise figure of 4.5 dB, a conversion gain of 43.5 dB, an out-of-band input-referred third-order intercept point of 7.89 dBm, and an IIP2 of more than 55 dBm.