An Inductor-Less Zero-IF Down-Conversion Mixer With Low Flicker Noise and High Conversion Gain

Abstract

This paper presents a novel active inductor (AI) to improve the performance of a down-conversion active mixer in terms of conversion gain (CG) and flicker noise. The proposed AI exhibits negative resistance and partially flat inductance over a wide frequency band of 0.5–4.5 GHz. The effect of inserting the AI between the source of the switching quad of a Gilbert cell mixer is theoretically analyzed. The proposed inductor-less mixer, designed to operate at a 2.4-GHz RF input frequency and a 10-MHz IF output frequency, employs current reuse and self-forward body bias (SFBB) techniques. The proposed circuit is simulated in Cadence Spectre-RF using RF-TSMC 0.18-μm CMOS technology. Post-layout simulations demonstrate that the proposed AI significantly reduces flicker noise by over 23 dB at an IF output frequency of 1 kHz and improves the CG by over 16 dB at an RF frequency of 2.4 GHz. The proposed mixer achieves a CG of 37.6 dB and a flicker noise corner frequency of 6 kHz. Additionally, it exhibits a third-order intermodulation intercept point (IIP3) of −5.2 dBm and a double-sideband noise figure (DSB-NF) of 6.1 dB at the IF output frequency of 10 MHz. Operating with a 1.5-V supply, the proposed mixer consumes 10.6 mW of power.