Patent ID: 11885646
Assignee: ALLEGRO MICROSYSTEMS, LLC
Field: Measurement (Instruments)
Classification: CPC G  H | IPC G  H

Claim 0:
1. A detector system, comprising:
a photodetector;
an amplifier having an input to receive an output from the photodetector;
a discriminator to receive an output from the amplifier and generate an active output signal when the output from the amplifier is greater than a threshold; and
an injection circuit coupled to the input of the amplifier, wherein the injection circuit is configured to selectively inject a test pulse that mimics a pulse from the photodetector for verifying operation of the detector system,
wherein the injection circuit comprises:
an injection capacitor coupled to the input of the amplifier, wherein the injection capacitor is sized to mimic the pulse from the photodetector, wherein the amplifier comprises a transimpedance amplifier to convert an input voltage to an output current;
a logic gate to receive a step signal and pixel row and column signals for the photodetector within an array and output a step lim signal;
an inverter coupled to the output of the logic gate to generate an inverted step lim signal;
a first switch controlled by the step lim signal, wherein the first switch is coupled between a voltage injection signal and the injection capacitor;
a second switch controlled by the inverted step lim signal, wherein the second switch is coupled between the injection capacitor and a voltage reference,
wherein the step-lim signal and the inverted step lim signal are rate-limited to control a width of the test pulse and to control slope to shape an output from the injection capacitor.