FPGA-based floating-point data acquisition system with automatic-gain-control and peak-detection for multi-channel electrochemical measurement

In this work we describes the design and engineering of a floating-point (FP) data-acquisition system for 16-channel electrochemical (EC) measurement. The system has both automatic gain and peak detection feature. The gain is set automatically dependent on the input amplitude so that at least 13-bit conversion resolution is maintained for the EC signal in the wide range from 48nA to 16mA. Peak detectors (PD) are used to acquire the peak signal accurately and automatically to avoid missing important information in the multi-channel EC detection. The system consists of 16 uniform automatic gain control (AGC) subsystems that operate in parallel. Compared with most of the other AGC systems, the mixed analog/digital implementation presented here operates without ADC sampling and software processing, so that the gain-setting time is minimized to 20ns. For the simple but efficient control mechanism, all digital circuits of the system can be integrated into a small-scale FPGA chip. Compared with commercial EC instrument, these characters make this FP data-acquisition system ideal for in situ or field multi-channel EC measurements.