Qualcomm Incorporated

Gerrit Groenewold

Peter J Shah

Shahin Mehdizad Taleie

Guoqing Miao

Eunyung Sung

A switched-capacitor DC blocking amplifier is disclosed. In an embodiment, an integrated circuit is provided that includes an amplifier having an amplifier input and an amplifier output, a capacitor connected to the amplifier input and configured to receive an input signal, and a switched capacitor circuit coupled to provide a resistance between the amplifier input and the amplifier output. In one implementation, the switched capacitor circuit is configured with a feed forward circuit to reduce aliasing. In another implementation, the switched capacitor circuit includes a switched impedance circuit to reduce noise.

Switched-capacitor DC blocking amplifier

Short-circuit protection in switched output stages is described to protect switching output stages from excessive output current in short-circuit conditions which may cause device damage. Design techniques to attain this goal include measuring currents in switching transistors by placing a scaled transistor in parallel thereto, combined with circuitry for making drain voltages substantially equal. The various techniques for short-circuit protection comprise (a) using a transistor and an operational amplifier in combination, (b) using a single transistor in place of the operational amplifier, (c) using a circuit to generate over-current detection signals, (d) providing over-current detection signals to a driver in order to reduce the output current, (e) using an inverter to feedback regulate output current, (f) using a switch to bypass the current regulator during normal operation, and (g) automatically opening this switch in an over-current situation.

Short-circuit protection for switched output stages

A switched capacitor sigma-delta modulator or another analog-to-digital converter (ADC) uses chopper stabilization. Chopping clock transitions are performed during non-active periods of the sampling clock phases, reducing disturbance of the circuit caused by chopping and increasing the time available for settling of the circuit given a particular sampling frequency. An asynchronous state machine may govern sampling and chopping clock transitions. In embodiments, inactive transition of a first sampling clock causes inactive transition of a second chopping clock, which in turn causes active transition of a first chopping clock. The next inactive transition of the first sampling clock causes inactive transition of the first chopping clock, which causes an active transition of the second chopping clock.

Growing community of inventors

Ramona, CA, United States of America

Gerrit Groenewold