公开(公告)号：US20190379984A1

公开(公告)日：2019-12-12

申请号：US16549625

申请日：2019-08-23

Applicant: Cirrus Logic International Semiconductor Ltd.

Inventor： Hynek SAMAN ,  James Thomas DEAS

IPC: H04R19/04 ,  H04R19/00 ,  H03F3/45 ,  H03F3/187

Abstract: This applications relates to methods and apparatus for amplifying signals from capacitive transducers, in particular MEMS transducers such as MEMS capacitive microphones. An amplifier circuit has a signal node for receiving the input signal, a transducer biasing node for outputting a transducer bias voltage for biasing the capacitive transducer, and a voltage buffer configured to generate a buffered bias voltage at a buffer node. An amplifier arrangement is configured to receive the input signal from the signal node and the buffered bias voltage. The amplifier circuit comprises a signal path for supplying the buffered bias voltage to the transducer biasing node via a first capacitance, and the amplifier arrangement comprises a feedback resistor network configured such that: a change in input signal with respect to the buffered bias voltage results in a change in the output signal with respect to the buffered bias voltage with a gain greater than one; and a change in the buffered bias voltage results in a change in the output signal with a gain equal to one.