Codec enhances voice recording in digital cameras

Asahi Kasei EMD Corp. releases AK4646, a low-power, high quality stereo ADC and DAC, as the latest addition to its expanding Audio2go range of products. The new device features a built-in microphone amplifier, an auto level control (ALC) circuit and a high-performance noise filter, making it suitable for digital video cameras, still cameras and other voice recording equipment.

The single-chip stereo codec incorporates high performance digital filtering which will enhance the performance of voice processing. A high-pass filter virtually eliminates external wind-noise, while a five-band equalizer can perform as a notch filter to minimize mechanical noise generated from within the camera. A stereo emphasis filter improves the recording performance of miniature stereo recording devices where the left and right channel stereo microphones are in close position.

The codec provides low-noise preamplifiers for microphones, supporting both differential and single-ended inputs. Other features are a power supply circuit for condenser microphones, an ALC circuit and digital volume control for recording/playback and a 400mW speaker amplifier. Sampling rates range from 7.35- to 48kHz and the operating voltage ranges from 2.2V to 3.6V.

AK4646 is equipped with a power-supply management function for the on/off control of each circuit block and a three wire microprocessor interface. A separate 1.6V digital power supply allows a direct interface with other chips, such as a CPU for low power consumption.

AK4646 is available in a 32-pin QFN package measuring 5-by-5-by-0.5mm pitch. Evaluation boards and samples are available now.