IP builds common-mode noise-resilient audio CODEC for automotive infotainment SoCs

August 11, 2014 // By Graham Prophet
Dolphin Integration has an audio CODEC targeting automotive infotainment applications, sCODS100-N.11-Xenon, providing optimal voice command and in-cabin phone conversation performances for high-end listening sound system.

A tier-one automotive Original Equipment Manufacturer (OEM) has partnered with Dolphin Integration by approving the performance and configuration of this audio CODEC according to automotive application requirements and by purchasing the infotainment module with this audio IP embedded inside.

Alongside the automotive AEC-Q100 standard requiring high operating temperature range, the major automotive application concern is the noisy ground. In order to overcome this issue, sCODS100-N.11-Xenon embeds a common-mode noise-resilient preamplifier in the ADC path and provides a unique “Common Mode Noise Tolerance Template (CMNT2)” specifying the tolerated noise beyond audio bandwidth. Further information on the common-mode management technique, is available in a technical article published by Dolphin Integration.

A second innovation is that an inter voltage-domain isolation-system enables independent start-up and power-down of analogue and logic power supplies of the CODEC, with control signal connected to SoC's Activity Control Unit (ACU) for ensuring safe behaviour of the IP during power-on and power-off sequences.

The codec features;

Two stereo ADCs with four stereo single-ended or differential inputs for line-in or mic-in application, and two stereo digital microphone inputs

Three stereo DACs with three stereo singled-ended line outputs for 5.1 in-car sound system

Automatic Gain control (AGC) on the recording path preventing from saturation of audio signals

Automatic Fs synchronisation system with an Audio Data Adaptive Synchroniser (ADAS) for both ADC and DAC

Jerk-less solution ensuring the best resilience to Fs frequency shift on audio data path

PLL-less solution for eliminating jittered PLL with direct fixed main clock support

Low noise regulator for highest resilience against power supply noise

Pop-up Noise (PuN) reduction circuitry for line-out

Specifications include;

For line/mic in to ADC path:

CMRR (@ a frequency from 20 to 20 kHz): 85 dB (minimum)

SNR (A-weighted): 90 dB (typical) / 85 dB (minimum)

THD+N (@ FS-1 dB): -80 dB (typical) / -75 dB (maximum)

PSRR (@ 1 kHz): 90 dB (typical)

For DAC to line-out (with 3 kOhm load minimum)