A 64-Channel Data Acquisition System-Based Ultralow Noise Transimpedance Amplifier for an Ionization Profile Monitor

Abstract

To meet the high time-resolution requirements of a fast ionization profile monitor (IPM), a 64-channel electrical signal acquisition system with a fast response frequency of 1 MHz has been developed. This article initially describes an ultralow noise transimpedance amplifier, which is an analog front-end (AFE) electronics aiming to achieve a balance between the accuracy and bandwidth, as well as to truly reflect the microstructure of short beam pulses. Subsequently, a synchronized multichannel data transmission system based on field-programmable gate arrays (FPGAs) transmits data streaming with the low latency and high throughput, and meanwhile, it provides data homogeneity in time across channels. The system is designed in a modular way to easily extend up to 128 channels. The nonlinearity of the readout electronics is less than 0.2% in the dynamic range of 15 nA– <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$15~\mu \text{A}$ </tex-math></inline-formula> , and the relative resolution is 0.15% at the input current of 15 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{A}$ </tex-math></inline-formula> . The spurious-free dynamic range (SFDR) is about 82.43 dB at a fundamental frequency of 1 kHz, and the effective number of bits (ENOB) of the analog-to-digital conversion (ADC) is better than 13 bits. The relative synchronization time discrepancy between channels is better than 2.5% of the sampling cycle. Finally, the system is deployed for the beam profile measurement with an IPM. The obtained peak value shows a good proportionality with the beam intensity increment, and all the electronics properties achieve reasonable and excellent performance.