A 24 GHz Direct Conversion Receiver for FMCW Ranging Radar Based on Low Flicker Noise Mixer

Dongze Li,Hudong Chang,Qingzhen Xia,Jiawei Huang,Bing Sun,Jinwei Li,Honggang Liu

doi:10.3390/electronics10060722

Abstract

In this paper, a 24 GHz direct conversion receiver (DCR) for frequency-modulated continuous-wave (FMCW) ranging radar based on low flicker noise mixer in 90 nm silicon-on-insulator (SOI) CMOS technology is presented. A low-noise and low-power low-noise-amplifier (LNA) adopting simultaneous noise and input matching (SNIM) method is designed. Neutralized technology and boost inductor are introduced to improve performance. The measurement results of standalone LNA show that the peak gain is 17.2 dB at 23.8 GHz and the −3 dB bandwidth is around 2.2 GHz from 22.8 GHz to 25 GHz. The LNA achieves an average 3 dB NF within the 24 GHz band. A current-bleeding mixer is used to lower noise and the factors influencing flicker noise have been discussed. Proper element values and local oscillator (LO) power have been chosen to make the mixer low-noise. Measurement results illustrate that the receiver exhibits 20.3 dB peak gain, 7 dB SSB noise figure (NF) and −22 dBm IP1dB. Flicker noise of the mixer and the receiver are measured respectively and the noise knee-point of receiver is observed 60 kHz. The receiver consumes only 16 mW with chip area of 0.65 mm2 including pads. The results demonstrate that the proposed receiver can be a promising candidate for FMCW ranging radar.

Highlights

Since the Federal Communications Commission (FCC) granted unlicensed 24 GHz band as Industrial Scientific Medical (ISM) band, intense research activity toward realization of highly integrated solutions around 24 GHz band is presently underway [1]
The results indicate that larger local oscillator (LO) power can reduce the flicker noise of receiver, same as the simulated results
To enhance gain of the receiver and reduce noise figure (NF), the simultaneous noise and input matching (SNIM) method was used in the input

Summary

Introduction

Since the Federal Communications Commission (FCC) granted unlicensed 24 GHz band as Industrial Scientific Medical (ISM) band, intense research activity toward realization of highly integrated solutions around 24 GHz band is presently underway [1]. The classical direct-conversion receiver has attracted wide-spread attention recently for its simple architecture and easy integration with the baseband circuit, as well as for its low power consumption and potentially low manufacturing costs [1]. The designs mainly cover the implementation and optimization of the low noise amplification and subsequent frequency downconversion They are integrated into a low-power radar receiver radio frequency (RF) front-end. When a DCR radar is used to measure the distance, the intermediate frequency (IF) calculated from FMCW may lie in the high flicker noise area. No measured results have been reported on 24 GHz low flicker noise receiver. The burgeoning CMOS technology has become a hotspot for low-cost mm-wave radar chips [12] with its high integration and low cost. Results indicate that the proposed receiver promises for 24 GHz FMCW Ranging Radar

FMCW Principle

Circuit Implementations

LNA Design

Low Flicker Noise Mixer Design

Results

Conclusions