Qualcomm Incorporated

Sean Wang

Seyfollah Seyfollahi Bazarjani

Vincenzo Peluso

Louis Dominic Oliveira

Edward A Keehr

An on-chip detection circuit automatically detects when an external switch has been activated. When the device is initialized, the detection circuit measures the operating current and coverts the information into an analog voltage. The analog voltage is then processed through an on-chip analog-to-digital converter and the digitized result is stored as a reference value. To sense the open and close action of the off-chip mechanical switch, the device then takes a sample of the operating current periodically, digitizes this information and compares the sampled value to the reference value. A change in value larger than some predetermined level indicates the external switch has been activated.

On-chip detection circuit off-chip mechanical switch's open and close actions

A digital to analog converter augmented with Direct Charge Transfer (DCT) techniques. A digital to analog converter augmented with DCT and CDS techniques. A digital to analog converter augmented with Postfilter Droop Compensation.

Digital to analog converter augmented with direct charge transfer techniques

A control mechanism that can be used to control a &Sgr;&Dgr; ADC to provide the required level of performance while reducing power consumption. The &Sgr;&Dgr; ADC is designed with multiple stages (i.e., loops or sections), and provides improved performance (e.g., higher dynamic range) as more stages are enabled. The control mechanism selectively enables a sufficient number of stages to provide the required performance and disables remaining stages to conserve power. The control mechanism achieves this by measuring one or more characteristics (e.g., signal level) of the ADC input signal through a &Sgr;&Dgr; ADC that is similar to the &Sgr;&Dgr; ADC on the signal path, comparing the measured characteristic(s) to particular threshold level(s), and controlling the stages such that the desired objectives are achieved. In one implementation, the control circuit includes one or more detector stages, a conditioning circuit, and a signal processor. The detector stage(s) receive the input signal and provide a detected signal. The conditioning circuit receives the detected signal and provides conditioned samples. The signal processor receives the conditioned samples and provides a control signal that selectively disables zero or more &Sgr;&Dgr; stages in the &Sgr;&Dgr; ADC.

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Sean Wang