General-purpose high-speed integrated lock-in amplifier with 30 dB dynamic reserve at 20 MHz

Abstract

We present the design of a general-purpose high-speed integrated lock-in amplifier (LIA). The LIA measures the amplitude and phase of the input signal with frequencies from 15 to 20 MHz at SNR as low as 30 dB. The magnitude measurement circuitry relies on the band-pass filter and current integrator to extract the signal amplitude. The phase measurement circuitry relies on the phase-locked loop to extract the phase difference between the input signal and the reference signal. The designed LIA is fabricated in TSMC 0.18 μm technology. The LIA consumes 37 mW of power. The output signal dynamic range is 300 mV for 600 mV input signal variation, and therefore the output-to-input sensitivity is approximately 0.5 V/V.