Analysis and design of a transimpedance amplifier based front-end circuit for capacitance measurements

Abstract

In this study, transimpedance amplifier based front-end circuits which can be employed to measure small capacitances were designed, analyzed and simulated using analog electronic circuit simulator. The front-end circuit converts the current flowing through the measured capacitance into a modulated voltage value which contains information regarding the desired capacitance. The frequency-domain, time-domain, stability and noise analyzes were carried out numerically and in simulation environment using a circuit simulator. The analytical, numerical and simulation results can be used to design optimized, precise and stable transimpedance amplifiers with low-noise value. The measured capacitance value was 10 pF which is low enough to simulate various real-world applications. Three commercially available, off-the-shelf operational amplifiers with different peripheral passive components were employed for computer based analysis. The designed transimpedance amplifiers are suitable to connect with capacitance extraction circuits which use analog or digital demodulation techniques.

Analysis of Quenching Resistor Effect to Improve Stability of TIA Circuit for APD – A Secondary Publication

“…Typically, a TIA can be simply implemented with an operational amplifier with a feedback resistor from the output to the inverting input [1] , but this introduces polarization due to the parasitic capacitor of the PD, which leads to issues such as stability, bandwidth limitation, and oscillation of the output waveform [2] . Stability issues are usually analyzed as a closed-loop voltage loop transfer function where voltage noise is fed back by the TIA's feedback resistor [1][2][3][4][5] , while issues such as settling time and bandwidth limitations are analyzed as a current loop transfer function where the PD's current follows the TIA's feedback resistor to the output in an open loop [6] and is compensated by a determined feedback capacitor. The compensated TIA must be accurately compensated for stability and settling time to avoid oscillations and under/over-shooting of the output waveform.…”

Front-End Amplifiers for Tuning Forks in Quartz Enhanced PhotoAcoustic Spectroscopy

“…Thus, the QTF can be represented both as a current source and as a voltage source, each requiring an appropriate way to collect the generated signal. When represented as a current source, the front-end electronics for the QTF is implemented as a transimpedance amplifier, which is the most common configuration for sensitive elements generating current signals when externally stimulated [10][11][12]. In transimpedance amplifiers, the current signal is converted into a voltage signal by an operational amplifier, in which a feedback loop resistor defines the current-to-voltage conversion coefficient (i.e., transimpedance).…”