Qualcomm Technologies, Inc.

Qualcomm Incorporated

Julian Aschieri

William Cope

Tomer Saraf

A transducer system has 1) a MEMS transducer configured to produce an analog output signal in response to an incident acoustic signal, and 2) a modulator apparatus. The modulator apparatus includes an analog modulator configured to receive the analog output signal and produce a first digital signal as a function of the analog output signal. In addition, the modulator apparatus also has a digital converter configured to receive the first digital signal and produce a second digital signal as a function of the first digital signal. The analog modulator has an analog order while, in a corresponding manner, the digital converter has a digital order. Preferably, the digital order is higher than the analog order.

Transducer with analog and digital modulators

A transducer system has a transducer configured to receive an incident signal and produce an output signal as a function of the incident signal. As known in the art, the output signal has a &#x2212;3 dB point. The transducer system also has circuitry operatively coupled with the transducer. The circuitry includes an amplifier with an output configured to produce an amplified signal as a function of the output signal. In addition, the circuitry further has a positive feedback loop and a negative feedback loop that both are electrically coupled between the transducer and the amplifier. The positive feedback loop is configured to move the &#x2212;3 dB point in a first frequency direction. Conversely, the negative feedback loop is configured to move the &#x2212;3 dB point in a second frequency direction. Preferably, the first and second frequency directions are different.

Transducer system with three decibel feedback loop

Certain aspects of the present disclosure provide amplifiers. Certain aspects of the present disclosure provide methods and apparatus for protecting an such amplifiers, for example an audio amplifier, or a delta-sigma modulator from saturation. One example amplifier generally includes an output stage comprising a plurality of transistors; and a feedback network having an input coupled to an output of the output stage and comprising a plurality of integrators connected in series. At least one of the plurality of integrators generally includes an operational amplifier having an input and an output, a first resistive element coupled to the input of the operational amplifier, a capacitive element coupled between the input and the output of the operational amplifier; and a first switch coupled between the input and the output of the operational amplifier. For certain aspects, the amplifier may be a class-D amplifier or a direct digital feedback amplifier (DDFA).

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Sharon, MA, United States of America

Julian Aschieri