AT73C209_14 Datasheet, PDF (42/63 Pages) ATMEL Corporation – SPI Interface and Internal Programming Registers

11. Microphone Preamplifier (OP065)
11.1 Features
• Standard Quality Amplifier for Electret Microphone Preamplifier
• Low Power Consumption
• Few External Components Necessary for a Complete Preamplifier
• Internal Bias
• Internal Bias for the Electret Microphone
• Stand-by Mode
11.2 Description
The OP065 is a low-voltage operational amplifier designed for a standard quality electret micro-
phone preamplifier. It presents a frequency response, a supply rejection and a noise compatible
with voice quality applications. All voltages are referred to gnda. The OP065 is powered by vdda
pin, with a nominal voltage of 2.8V. The normal operating mode is defined with ONAMP and
ONMIC pins set to 1 (referred to vdda).
11.3 Functional Diagram
Figure 11-1. Microphone Preamplifier Functional Diagram
560k
micinn
vcm
micb
6.8k
2.2k
OP065
micout
42 AT73C209
6365A–PMAAC–12-Mar-08