Signal monitoring and control system for an optical navigation sensor

A gain control circuit to control strength of signals received from an array of photo-detectors in an optical navigation sensor, the gain control circuit comprising:

• a number of transimpedance-amplifiers (TIAs) each including an input coupled to an output of at least one photo-detector (PD) in the array to receive a current signal therefrom and to generate an automatic gain control (AGC) signal in response thereto;
• and
• a controller coupled to outputs of the number of TIAs to receive the AGC signal therefrom, the controller including logic to execute a signal gain adjustment algorithm and to adjust a gain of a signal processor coupled to the array of PDs in response to the AGC signal,
• wherein the optical navigation sensor is included in an input device to sense displacement of the input device relative to a surface and the optical navigation sensor further comprises an illuminator to illuminate at least a portion of the array with light reflected from the surface, and wherein the controller is configured to adjust illumination from the illuminator.

A gain control circuit to control strength of signals received from an array of photo-detectors in an optical navigation sensor, the gain control circuit comprising:

• a number of transimpedance-amplifiers (TIAs) each including an input coupled to an output of at least one photo-detector (PD) in the array to receive a current signal therefrom and to generate an automatic gain control (AGC) signal in response thereto;
• and
• a controller coupled to outputs of the number of TIAs to receive the AGC signal therefrom, the controller including logic to execute a signal gain adjustment algorithm and to adjust a gain of a signal processor coupled to the array of PDs in response to the AGC signal,
• wherein the number of TIAs comprise a plurality of TIAs, each of the plurality of TIAs including an input coupled to a number of PDs located in a contiguous area of the array different from PDs coupled to another of the plurality of TIAs, and wherein the controller further includes logic to determine a spatial distribution of light level across the array of PDs using AGC signals from the plurality of TIAs.

An optical navigation sensor to sense displacement of an input device relative to a surface, the optical navigation sensor comprising:

• an illuminator to illuminate at least a portion of the surface;
• an array of photo-detectors (PDs) to receive light reflected from the illuminated portion of the surface;
• a signal processor coupled to outputs of PDs in the array of PDs to integrate current signals received therefrom and output a voltage signal generated in response thereto;
• and
• a gain control circuit for controlling strength of signals from the array of PDs, the circuit including a number of transimpedance-amplifiers (TIAs) each including an input coupled to an output of at least one of the PDs in the array to receive a current signal therefrom and to generate an automatic gain control (AGC) signal in response thereto, and a controller coupled to outputs of the number of TIAs to receive the AGC signal therefrom, the controller configured to adjust an integration time of the signal processor over which the received current signals are integrated in response to the AGC signal.

A method of controlling strength of signals from an array of photo-detectors (PDs) in an optical navigation sensor, the method comprising:

• coupling to an input of at least one of a number of transimpedance-amplifiers (TIAs) a current signal from an output of at least one of the PDs in the array and generating an automatic gain control (AGC) signal in response thereto;
• coupling the AGC signal to a controller and executing therein a signal gain adjustment algorithm to generate control signals in response to the AGC signal;
• and
• coupling the control signals to a signal processor coupled to the array of PDs and adjusting a gain of the signal processor in response thereto,
• wherein the signal processor comprises a number of differential transimpedance-amplifiers (DIFF-TIAs) each including inputs coupled to the array of PDs to receive current signals therefrom and output a voltage signal generated in response thereto.