A Sub-1-GHz band high-dynamic-range receiver with integrated self-adaptive multipart AGC loops

Abstract

This article presents a fully differential high-dynamic-range direct-conversion receiver for sub-1-GHz band applications in a 180-nm CMOS technology. The integrated self-adaptive multipart automatic gain control (AGC) loops are designed to cope with large input signal. In the radio frequency (RF) domain, a gain-adjustable noise-canceling balun low-noise amplifier (LNA) and a high-linearity RF variable gain amplifier (VGA) are co-designed to keep a steady differential output power for the mixer stage. In baseband (BB), a novel gain distribution method is proposed to protect BB circuits from saturation. To prove the concept, one of the most typical and strict application scenarios in the sub-1-GHz band, digital television (DTV) standard, is analyzed and chosen as the design target. The receiver achieves a noise figure (NF) of 3.6-4.6 dB in the ultrahigh-frequency (UHF) band. A wide gain tuning range of 128.8 dB is realized in this work, featuring fully integrated AGC loops. The programmable bandwidth of the low-pass filter (LPF) can be adjusted from 1 to 4 MHz, supporting 2-/6-/7-/8-MHz signal channels. The maximum in-band third-order input-referred intercept point (IIP3) is 10 dBm under the conversion gain of 0 dB. The receiver consumes 49.56 mA from a 1.8-V voltage supply and occupies an area of 3.56 mm2.