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

Abstract

In this article, a blocker-tolerant receiver (RX) front end employing a dual-band <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> -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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> -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 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> -path balun-LNA, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$G_{m}$ </tex-math></inline-formula> -stage, current-mode passive mixers with a 25% duty-cycle local oscillator signal, current-mode passive <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RC</i> 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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , 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.