The CMAMP110 Microphone Amplifier selects (via MIC_SELECT) between and amplifies Internal and External Microphone input signals. The device is designed to be compliant with Microsoft PC99 and PC2001 specifications. The CMAMP110 contains the equivalent of 7 operational amplifiers and 19 precision resistors, and is intended for use in PC audio applications. The Internal Microphone input is differential, but it can also be used single-ended by simply grounding one of the inputs through a capacitor. The External Microphone input is single-ended. A logic high level on the MIC_SELECT pin selects the external microphone input. Since the chip supplies the DC bias for the external microphone (EXT_MIC_BIAS), both dynamic and electret type microphones may be used. The output amplifier is unity gain stable and is capable of driving a resistive load in excess of 10K.