Determination of the electronics transfer function for current transient measurements

TL;DR

This paper presents a Fourier transform-based method to accurately determine the transfer function of sensor readout systems using simulated current transients, enabling improved analysis of sensor responses in various conditions.

Contribution

The paper introduces a straightforward Fourier-based approach to extract the transfer function from simulated sensor data, enhancing the analysis of transient current measurements.

Findings

The transfer function accurately reproduces measured transients for different wavelengths and voltages.

Simulated sensor responses convolved with the transfer function match experimental data well.

Method applicable to analyze radiation-damaged sensors and drift velocity dependencies.

Abstract

We describe a straight-forward method for determining the transfer function of the readout of a sensor for the situation in which the current transient of the sensor can be precisely simulated. The method relies on the convolution theorem of Fourier transforms. The specific example is a planar silicon pad diode connected with a 50 $\Omega $ cable to an amplifier followed by a 5 GS/s sampling oscilloscope. The charge carriers in the sensor were produced by picosecond lasers with light of wavelengths of 675 and 1060 nm. The transfer function is determined from the 1060 nm data with the pad diode biased at 1000 V. It is shown that the simulated sensor response convoluted with this transfer function provides an excellent description of the measured transients for the laser light of both wavelengths, at voltages 50 V above the depletion voltage of about 90 V up to the maximum applied voltage of 1000 V. The method has been developed for the precise measurement of the dependence of the drift velocity of electrons and holes in high-ohmic silicon on crystal orientation, electric field and temperature. It can also be applied for the analysis of transient-current measurements of radiation-damaged solid state sensors, as long as sensors properties, like high-frequency capacitance, are not too different.