Abstract: An attenuator includes a first stage 601a having a first operational amplifier 602a and a tapped resistor 603a. Tapped resistor 603a has an input for receiving input data, an output coupled to an output of first operational amplifier 602a, and a plurality of taps for selectively presenting a sequence of voltages to a noninverting input of first operational amplifier 602a. Each of these sequences of voltages corresponds to an attenuation step such that first stage 601a steps the attenuation produced by the attenuator from an intermediate value to a predetermined ending value. A second stage 601b includes a second operational amplifier 602b and a tapped resistor 603b. Tapped resistor 603b includes an input for receiving analog data from first stage 601a, an output coupled to an output of second operational amplifier 602b, and a plurality of taps for selectively presenting a sequence of voltages to a noninverting input of operational amplifier 602b.

Abstract: Audio data processing circuitry 300 includes a plurality of analog inputs 101 for receiving analog audio data and a digital input 105 for receiving digital audio data. A analog mixer 312 mixes analog data received at said plurality of analog inputs 101 to generate a mixed analog audio stream. An analog-to-digital converter 313 converts the mixed analog audio stream to a digital audio stream and a digital mixer 315 mixes digital data received at the digital input 105 with the digital audio stream from the analog mixer 312 to generate a mixed digital audio stream.