A CMOS 1.2-V 1.7-mW lock-in amplifier for sensing applications up to 0.7-MHz

This paper proposes a 1.2-V 1.7-mW 0.7-MHz bandwidth dual-phase analog lock-in amplifier (LIA) for embedded sensing applications integrated in a 0.18-μm CMOS technology. Unlike to most of the reported up-to-date LIAs, which are designed to condition a specific sensor operating at a particular frequency, this work presents a general purpose low power battery-compatible LIA, so that the benefits of phase sensitive detection (PSD) techniques in sensor signal processing can be exploited in a wider spectrum of applications, such as multi-sensing devices. Additionally, a high simplicity and versatility with a good trade-off between its main performances and power has been sought. Experimental results for signals buried in white noise confirm the capability of the LIA to effectively recover information from signal-to noise power ratios up to -33 dB with errors below 2 % up to 0.7 MHz with 1.7 mW of power consumption, showing up that higher frequency operation with a reduction in voltage supply and power with respect to previously reported LIAs is achieved.