Patent ID: 6853733

Claim:
An apparatus for interfacing a microphone, comprising: a receiver circuit that includes a first ground terminal and a line terminal, wherein the receiver circuit is arranged to couple the line terminal to the first ground terminal through a line termination impedance; and a digital microphone circuit that includes a second ground terminal and a power terminal, wherein the second ground terminal is coupled to the line terminal by a voltage active line, the digital microphone circuit comprising: a local ground, wherein the microphone is coupled between the power terminal and the local ground; an analog-to-digital converter circuit is coupled between the power terminal and the local ground, wherein the analog-to-digital converter circuit is arranged to provide an ADC output signal that is responsive to the microphone; a clock detect circuit that is arranged to coupled to the voltage active line and arranged to provide a detected clock signal, wherein the detected clock signal is coupled to the analog-to-digital converter and a data current generator; and a data current generator circuit is coupled to between the power terminal and the second ground terminal, wherein the data current is arranged to provide a data signal to the voltage active line in response to the ADC output signal.