Resistorless Current-Mode Schmitt Trigger for Single-Event Detection in Photomultipliers Front-Ends

This work proposes an integrated current-mode non-inverting Schmitt Trigger in a 150nm CMOS technology, without any feedback passive element, for photomultipliers single-event detection. The proposed device is triggered by a current input signal and provides an output voltage that is suitable for interfacing with digital systems. The small currents associated with a reduced number of photoelectrons require a high transimpedance gain and a narrow hysteresis width, making conventional approaches impractical. The proposed device shows a current threshold value to trigger the system, offering a high detection capability also with small currents. In addition, it makes the trigger hysteresis width less sensitive to supply variations. The proposed circuit has great design flexibility, also allowing user to tune the threshold currents using bias voltage reference. The proposed device properly operates under a power supply voltage 1.8 V to 3.3 V. Static power consumption is 10 μW, with a propagation delay of 25 ns and a total detection delay of 34 ns, driving a 3 pF load capacitance.