The PolySense team has just published a new article on Micromachines reporting on a theoretical study of the Signal-to-Noise Ratio trend in a voltage-mode read-out of Quartz Tuning Forks (QTFs), mainly focusing on the effects of (i) the noise contributions of both the QTF-equivalent resistor and the input bias resistor RL of the preamplifier, (ii) the operating frequency, and (iii) the bandwidth (BW) of the lock-in amplifier low-pass filter.
When the bandwidth of the lock-in filter is sufficiently narrow (BW = 0.5 Hz), the SNR values do not strongly depend on both the operating frequency and RL values. On the other hand, when a wider low-pass filter bandwidth is employed (BW = 5 Hz), a sharp SNR peak close to the QTF parallel-resonant frequency is found for large values of RL (RL > 2 MΩ), whereas for small values of RL (RL < 2 MΩ), the SNR exhibits a peak around the QTF series-resonant frequency.
The following link provides access to the article:
http://polysense.poliba.it/wp-content/uploads/2023/03/155_micromachines-14-00619_2023.pdf
