Optimized Embedded QCM-D System Based on FPGA

This work presents a low-cost quartz crystal microbalance with dissipation (QCM-D) monitoring system implemented on a field programmable gate array (FPGA) platform. The design optimizes the tradeoff between measurement accuracy and system complexity by improving the analog front-end, signal acquisition, and digital signal processing stages. A short-circuit current readout configuration minimizes the effects of parasitic capacitances and load resistance, ensuring that the measured transient depends only on the electromechanical behavior of the resonator. The system employs a direct digital synthesizer (DDS)-driven mixing stage for downconversion to baseband, followed by adaptive processing on the FPGA, which extracts the resonance frequency and dissipation factor with high precision. In addition to the system implementation, this article includes an analysis of the main measurement errors and uncertainty sources, providing a systematic framework to assess the overall metrological performance of this type of architecture. Experimental results demonstrate frequency errors in the parts-per-million (ppm) range and dissipation errors on the order of 103 , confirming that accurate and repeatable QCM-D measurements can be achieved using compact and cost-effective FPGA-based instrumentation suitable for both laboratory and portable applications.