This paper presents a new micropower analog lock-in amplifier (LIA) suitable for battery-operated applications thanks to its reduced size and power consumption as well as its operation with single-supply voltage. The proposed LIA was designed in a 0.18 µm CMOS process with a single supply voltage of 1.8 V. Experimental results show a variable DC gain ranging from 24.7 to 42 dB, power consumption of 417 µW and integration area of 0.013 mm². The LIA performance was demonstrated by measuring carbon monoxide concentrations as low as 1 ppm in dry N₂. The experimental results show that the response to CO of the sensing system can be considerably improved by means of the proposed LIA.

This paper presents the design and experimental characterization of a portable high-precision single-phase lock-in instrument with phase adjustment. The core consists of an analog lock-in amplifier IC prototype, integrated in 0.18 µm CMOS technology with 1.8 V supply, which features programmable gain and operating frequency, resulting in a versatile on-chip solution with power consumption below 834 µW. It incorporates automatic phase alignment of the input and reference signals, performed through both a fixed −90° and a 4-bit digitally programmable phase shifter, specifically designed using commercially available components to operate at 1 kHz frequency. The system is driven by an Arduino YUN board, thus overall conforming a low-cost autonomous signal recovery instrument to determine, in real time, the electrical equivalent of resistive and capacitive sensors with a sensitivity of 16.3 µV/Ω @ ε_rS < 3% and 37 kV/F @ ε_rS < 5%, respectively.

The design and experimental characterization of a high-resolution analog lock-in amplifier (LIA)-based measurement system is presented in this paper. Different design strategies are used to attain a versatile solution which features programmable gain (72.6-82.6 dB) and operating frequency (5-115 kHz), preserving good recovery performance. The prototype, integrated into the United Microelectronics Corporation 0.18-μm CMOS process with a single supply voltage of 1.8 V, achieves a resolution of 200 nV and a high dynamic reserve of 43.5 dB, showing significantly lower power consumption (885 μW) than high-resolution state-of-the-art LIAs with minimum size (0.075-mm² silicon area). To validate the amplitude recovery performance of the proposed single-phase LIA, it was used to measure the equivalent value of a passive resistive sensor, exhibiting a maximum error of 1.9% when RS is varied from 100 Ω to 10 kΩ with an input signal in the order of hundreds of microvolts. Thus, it constitutes a highly suitable choice for portable and lab-on-a-chip sensing applications.

A new fully integrated micropower CMOS analogue lock‐in amplifier (LIA) is presented. To achieve a compact architecture able to operate under low voltage with low‐power consumption, it is based on a current‐mode amplifier with embedded rectification within the transconductance stage. Post‐layout results for a 0.18 µm CMOS implementation show a dynamic reserve of 51.2 dB, a power consumption of 482 µW and an integration area of 0.03 mm ² . The frequency operation ranges from 450 Hz to 1.1 MHz, whereas the gain is programmable from 39 to 59 dB, providing the LIA with flexibility to match a wide range of applications.