Low power measurement circuit for position sensor

In a cursor control system, a cursor control input device comprising:

• a columnar element operatively extending from a flexible substrate;
• a first pair of operatively coupled resistive elements mounted to the substrate, the resistivity of the first pair of resistive elements changing with flexing of the substrate;
• a second pair of operatively coupled resistive elements mounted to the substrate, the resistivity of the second pair of resistive elements changing with flexing of the substrate;
• a current source;
• means for selectively coupling the first and second pair of resistive elements to the current source creating a resistive network;
• a first signal indicative of the resistivity of a first resistive element of the resistive network;
• a second signal indicative of the resistivity of a second resistive element of the resistive network;
• and
• a signal processing circuit receiving the first signal and the second signal, the signal processing circuit providing an output indicative of the magnitude of a force applied to the columnar element.

A signal processing system for reducing a sensor's power consumption, the signal processing system comprising:

• a controller including signal processing logic;
• a switch coupling the sensor to a power source, the switch receiving a first signal from the controller;
• an amplifier receiving a second signal from the sensor;
• a sample and hold circuit receiving a third signal from the amplifier and receiving a fourth signal from the controller;
• and
• an analog to digital converter receiving a fifth signal from the sample and hold circuit.

A signal processing system for a sensor, the sensor including a set of resistive elements, the signal processing system comprising:

• means for selectively energizing a subset of the set of resistive elements to create an energized resistive network;
• means for processing a first signal received from the energized resistive network;
• and
• means for controlling the means for selectively energizing a subset of the set of resistive elements to create an energized resistive network and the means for processing a first signal received from the energized resistive network.