Abstract
This paper proposes a battery-compatible electronic interface based on a general purpose lock-in amplifier (LIA) capable of recovering input signals up to the MHz range. The core is a novel ASIC fabricated in 1.8 V 0.18 µm CMOS technology, which contains a dual-phase analog lock-in amplifier consisting of carefully designed building blocks to allow configurability over a wide frequency range while maintaining low power consumption. It operates using square input signals. Hence, for battery-operated microcontrolled systems, where square reference and exciting signals can be generated by the embedded microcontroller, the system benefits from intrinsic advantages such as simplicity, versatility and reduction in power and size. Experimental results confirm the signal recovery capability with signal-to-noise power ratios down to −39 dB with relative errors below 0.07% up to 1 MHz. Furthermore, the system has been successfully tested measuring the response of a microcantilever-based resonant sensor, achieving similar results with better power-bandwidth trade-off compared to other LIAs based on commercial off-the-shelf (COTS) components and commercial LIA equipment.
Highlights
Cyber physical systems (CPS) embody one of the major driving forces that go beyond the cyber world toward the physical world
That allow a precise frequency selection and phase shift. This feature allows using the microcontroller to generate in each cog two accurate square signals in quadrature configuration Vr and Vr90 required by the lock-in amplifier (LIA) to perform the phase sensitive detection (PSD) measurements
This paper proposes a LIA-based low-power electronic interface capable to recover input signals up to 1 MHz buried in high noise levels
Summary
Cyber physical systems (CPS) embody one of the major driving forces that go beyond the cyber world toward the physical world. A critical element is the electronic interface that conditions the sensing outputs into signals to be processed into embedded computers like microcontrollers (μC) [6]. Square-signal processing imposes high demands in the design of the LIA and its main blocks, especially in terms of slew rate and bandwidth. Their design needs to be optimized for a good trade-off between power and performance. In response to the above, this paper presents a LIA-based electronic general-purpose interface able to recover square input signals with frequencies as high as 1 MHz and buried in high noise levels.
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