Microphone Preamplifier Circuit

摘要

A microphone preamplifier circuit (60) is described, adapted to be connected to a microphone circuit (MCD), the microphone circuit (MCD) comprising a microphone (3) and at least one output node (MO, MO′). The microphone preamplifier circuit (60) comprises a preamplifier (PA) comprising: —at least one input node (10, 10′) adapted to be connected to said output node (MO, MO′); —an operational amplifier (OA) comprising at least one input (20, 20′) and at least one output (21, 21′); —at least one input DC decoupling capacitor (CD, CD′) connected between said input node (10, 10′) and said first input of the operational amplifier (20,20′); at least one feedback capacitor (C2A, C2A′) connected between the input (20,20′) and the output (21, 21′) of the operational amplifier (OA) in order to set together with said input DC decoupling capacitor (CD, CD′) a gain value of the preamplifier circuit (60); —a first (40, 40′) and a second feed node (41, 41′) adapted to be fed by a first (VCIMIN) and a second (VCM) bias voltage respectively. The preamplifier (PA) further comprises at least one switched capacitor (C2B, C2B′) adapted to be selectively and alternatively connected under the control of a clock signal (CK): —between said input (20, 20′) and said output (21, 21′) of the operational amplifier (OA); and—between said first (40, 40′) and said second (41, 41′) feed node.

主权项

1. Microphone preamplifier circuit adapted to be connected to a microphone circuit, the microphone circuit comprising a microphone and at least one output node, the microphone preamplifier circuit (60) comprising a preamplifier comprising:
at least one input node adapted to be connected to said output node; an operational amplifier comprising at least one input and at least one output; at least one input DC decoupling capacitor connected between said input node and said first input of the operational amplifier; at least one feedback capacitor connected between the input and the output of the operational amplifier in order to set together with said input DC decoupling capacitor a gain value of the preamplifier circuit; a first and a second feed node adapted to be fed by a first and a second bias voltage respectively; wherein said preamplifier further comprises at least one switched capacitor adapted to be selectively and alternatively connected under the control of a clock signal: between said input and said output of the operational amplifier; and between said first and said second feed node; and wherein said preamplifier further comprises an anti-aliasing filter having an output terminal connected to said input node and an input terminal connected/connectable to said output node of the microphone circuit.