Patent ID: 7247832
Filing Date: 2007-07-24
Classification: G01J

Abstract:
1. A signal processor for use with an optical navigation system, the signal processor comprising: a transimpedance amplifier (TIA) to integrate a current received from a photo-detector in the optical navigation system to generate a voltage signal having a slope that is proportional to the received current; a comparator having a first input coupled to an output of the TIA to receive the voltage signal, and a second, inverting, input coupled to a threshold voltage, the comparator configured to compare the voltage signal to the threshold voltage and to generate an output pulse having a predetermined voltage and a duration that is a function of the received current; and a sample and hold (S/H) circuit and a differential amplifier (Diff Amp) coupled between the TIA output and the first input of the comparator, wherein: the S/H circuit has an input coupled to the TIA output to sample and hold a voltage of the voltage signal at a first predetermined time following a reset of the signal processor; and the Diff Amp has a first input coupled to an output of the S/H circuit and a second input coupled to the TIA output to determine a difference between the voltage stored in the S/H circuit and a voltage of the voltage signal at the output of the TIA at a second predetermined time, whereby the voltage signal coupled to the first input of the comparator is independent of and substantially unaffected by reset noise from the TIA.