A Correlated Double Sampling Technique for Charge-Sensitive Amplifiers based on TFTs

In this work is presented a low-noise Charge Sensitive Amplifier (CSA) suitable for the readout of high-impedance pyroelectric sensors. The circuit exploits a novel Correlated Double Sampling (CDS) technique which allows both continuous-time integration and cancellation of the Thin-Film Transistor (TFT) 1/f noise. The CSA has been implemented in a printed unipolar Organic TFT technology and simulation results demonstrate a Signal-to-Noise Ratio (SNR) improvement of approximately 10 dB when the proposed CDS technique is applied at the frequency of 500 Hz. This result is expected e.g., to extend the proximity detection range and improve the safety in human-machine applications using large-area infrared-sensing surfaces. Moreover, the proposed technique can be used in generic Analog Frontend Electronics embedding switched capacitor amplifiers, to suppress correlated noise sources.