Design of Non-Uniform Sample and Hold Circuit for Biomedical Signal Processing Applications

Sara Bagher Nasrabadi ¹ (Department of Electrical Engineering- Najafabad Branch, Islamic Azad University, Najafabad, Iran)
Mehdi Dolatshahi ² (Department of Electrical Engineering- Najafabad Branch, Islamic Azad University, Najafabad, Iran)
Sayed Mohammad Ali Zanjani ³ (Smart Microgrid Research Center- Najafabad Branch, Islamic Azad University, Najafabad, Iran)
Hossein Poorghasem ⁴ (Digital Processing and Machine Vision Research Center- Najafabad Branch, Islamic Azad University, Najafabad, Iran)

Submited date : 2022-08-11 accepted date : 2022-12-10

Keywords: Low power, Sample and hold, Comparator, non-uniform sampling, biomedical signal,

Abstract :

By reducing the amount of data in bioprocessor circuits, the required memory and power consumption are reduced. Therefore, non-uniform sampling (NUS) is feasible, and a sample-and-hold circuit can be used to non-uniformly sample bio-signals and reduce the volume of the data from vital signals. In the present study, a new closed-loop non-uniform sample-and-hold circuit along with a differential clock generator circuit is proposed. The proposed design consumes low power and can minimize the volume of the generated bio-signal data in the frequency range corresponding to vital signals. The proposed non-uniform clock generator circuit uses two comparators with PMOS and NMOS inputs and a control circuit with a few logic gates. After detecting the rate of heart signal variations, the proposed circuit generates non-uniform clock signals at two frequencies of 1000 and 100 Hz for fast and slow variations, respectively. The output signal of the sampling circuit is reconstructed by using resampling and interpolation in MATLAB. Simulations are performed in Cadence in 0.18 µm technology with a supply voltage of 1.8 V. The simulation results show a percentage root mean square difference (PRD) of 2.3%, a mean square error (MSE) of 8.57×10-5 and a signal-to-noise ratio (SNR) of 71 dB. These results indicate the proper performance of the proposed circuit in comparison with previous designs.

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