Self-oscillating Double-balanced Mixer with Transformer Coupled Single-ended LNA Input

Abstract

This paper proposes a low flicker-noise, low-power, and single-ended radio-frequency (RF) front-end which is consisted of a low-noise amplifier (LNA) and a self-oscillating double-balanced mixer (SO-DBM), where the two blocks are coupled using a transformer. A cascode LNA is adopted for the RF input to reduce the output to input feedback and an external capacitor is included between the gate and source terminals to have a power-constrained simultaneous noise and input matching. The double-balanced mixer itself operates as a voltage-controlled oscillator (VCO) using a series inductor-capacitor network. The low intermediate frequency (IF) or baseband signal can be directly extracted from the drain nodes of the VCO switching transistors by adding simple resistor-capacitor (RC) filters. Using a 65 nm CMOS technology, the proposed single-ended input SO-DBM cell is optimized for the phase noise performance. Oscillating at around 2.4 GHz, the phase noise of the proposed SO-DBM is −65 dBc/Hz, −91 dBc/Hz, and −112 dBc/Hz at 10 kHz, 100 kHz, and 1 MHz offset frequency, respectively. The simulated voltage gain is about 43 dB. The double sideband noise figure is about 3.1 dB at 1 MHz offset frequency. The power consumption is 1.54 mW from a 1-V supply.