Multi-Phase Frequency Measurement Exploiting FPGA Mixed-Mode Clock Management for QCM-D Technology

We have proposed a digital frequency measurement technique with enhanced accuracy, exploiting FPGA Mixed-Mode Clock Management for QCM-D technology. In detail, the method is based on the multi-phase generalization of the basic direct period measurement technique, involving low-complexity digital architectures based on gated counters. Theoretical analysis has been validated by experimental results, referring to a design implemented on a Xilinx Artix-7 FPGA. The proposed solution allowed to reach a worst-case frequency measurement error of ≈ 20Hz for an observation period of
$200\mu \mathrm{s}$
of a damped QCM sensor resonating at 10MHz.