A PID control approach for time constant adaptation in digital multi-channel pulse amplitude analyzer

In digital multi-channel analyzers, improper shaping parameter settings can adversely affect signal resolution and energy accuracy. To address this, we propose an automatic tuning method based on a Proportional-Integral-Derivative (PID) control algorithm. The method quantifies the difference between the two ends of the flat-top of the trapezoidal pulse as the error input, and the PID output adjusts shaping parameters iteratively. Through theoretical analysis, we show that the endpoint difference exhibits a monotonic relationship with the trapezoidal shaping parameter M and admits a unique equilibrium point, providing a theoretical basis for convergence. Experimental results demonstrate the algorithm's stability and effectiveness in multi-channel systems. Compared with fixed shaping parameters, the proposed method improves the FWHM by 11.01%, while maintaining consistent peak heights despite analog front-end circuitry drift. This improvement enhances measurement reliability and mitigates the impact of long-term variations in the analog front-end circuitry, making it suitable for applications in nuclear radiation signal processing and analysis.