| 摘要 |
The output (INS) of the microphone is fed via an amplifier circuit (AC) and a decoupling capacitor (C) to the input (IS) of a comparator (COC). The comparator input is compared with reference voltages INT1,INT2) by two operational amplifiers (OA1,OA2). The two comparator outputs are fed to a NAND gate, the output of which is fed to the gate electrodes of a chain of MOS transistors (PM1,NM1). - The MOS transistors form part of a capacitor charge and discharge circuit (CDC). The capacitor (C2) is connected to an output transistor (NM1) which is in series with two resistors (R1,R2). The junction between the resistors is output (01) to a signal attenuation circuit, while the junction between the second resistor (R2) and the MOS transistor (NM1) is fed (02) to an amplitude control circuit.(1/1)
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