Simulation and measurement of image charge detection with printed-circuit-board detector and differential amplifier

We present a novel and thorough simulation technique to understand image charge generated from charged particles on a printed-circuit-board detector. We also describe a custom differential amplifier to exploit the near-differential input to improve the signal-to-noise-ratio of the measured image charge. The simulation technique analyzes how different parameters such as the position, velocity, and charge magnitude of a particle affect the image charge and the amplifier output. It also enables the designer to directly import signals into circuit simulation software to analyze the full signal conversion process from the image charge to the amplifier output. A novel measurement setup using a Venturi vacuum system injects single charged particles (with diameters in the 100 s of microns range) through a PCB detector containing patterned electrodes to verify our simulation technique and amplifier performance. The measured differential amplifier presented here exhibits a gain of 7.96 µV/e^- and a single-pass noise floor of 1030 e^-, which is about 13× lower than that of the referenced commercial amplifier. The amplifier also has the capability to reach a single-pass noise floor lower than 140 e^-, which has been shown in Cadence simulation.