Patent ID: 9554209
Date: 2017-01-24
CPC Classifications: H03F,H04R

Claim:
1. Microphone preamplifier circuit adapted to be connected to a microphone circuit, said microphone circuit comprising a microphone and at least one output node, said microphone preamplifier circuit comprising a preamplifier comprising: an operational amplifier comprising at least one input and at least one output; at least one input DC decoupling capacitor connected to said at least one input of said operational amplifier; at least one feedback capacitor connected between said at least one input and said at least one output of said operational amplifier in order to set together with said at least one input DC decoupling capacitor a gain value of said microphone preamplifier circuit; first and second feed nodes adapted to be fed by first and second bias voltages respectively; wherein said preamplifier further comprises at least one switched capacitor adapted to be selectively and alternatively connected in response to a clock signal: between said at least one input and said at least one output of said operational amplifier; and between said first and second feed nodes; wherein said microphone preamplifier circuit further comprises an anti-aliasing filter comprising: (i) at least one output terminal connected to said at least one input DC decoupling capacitor and (ii) at least one input terminal adapted to be connected to said at least one output node of said microphone circuit, and wherein said preamplifier and said anti-aliasing filter are integrated in a same chip.