A 2.5 kHz 50.57 dB Linearized VCO ADC Using 6 µm LTPS TFTs

This paper presents a VCO-based ADC design for use in flexible electronics, specifically leveraging Low-Temperature Polysilicon Thin-Film Transistor (LTPS TFT) technology. The design achieves a resolution of 8.11 bits at a 20 MHz sampling rate with a bandwidth (BW) of 2.5kHz. A linearity compensation technique combining a resistive input stage with a frequency-dependent resistor (FDR)-based feedback loop significantly enhances the VCO linearity. Simulation results validate the design, exhibiting an R
²
value of 0.9999 for the VCO tuning curve, a Signal-to-Noise and Distortion Ratio (SNDR) of 50.57 dB, and a Spurious-Free Dynamic Range (SFDR) of 52.34 dB at a supply voltage of 10V. The proposed design also features the lowest Figure of Merit (FoM) (0.73 nJ/conversion-step) compared with the state-of-the-art.