Out in Front: March 1, 1996

A/D-converter vendors are continuing the trend toward fitting higher performance into smaller packages, as two devices from Datel demonstrate. The ADS-946, an 8M-sample/sec, 14-bit resolution part, works in time-domain (medical imaging, scanners) and frequency-domain (radar, telecommunications, spectrum-analysis) applications. It includes an internal S/H amplifier, a reference, timing/control logic, and error-correction circuitry, along with a subranging, two-pass A/D converter.

The ADS-946 offers an S/N ratio of at least 78 dB and a THD of less than -80 dB. The ±5V device dissipates 1.9W and is scaled for a ±2V input range. The rising edge of a "start-convert" pulse initiates conversion; digital inputs and outputs are TTL-compatible. The converter comes in a 24-pin, ceramic, double-width DIP. It costs $488 (100) for a 0 to +70°C version and $644 for a -55 to +125°C version.

For higher resolution applications that can accept slower conversion rates, the ADS-932 provides 16-bit, 2M-sample/sec performance. It comes in a triple-width, 40-pin DIP, has an S/N ratio of 86 dB and a THD of -88 dB, and samples full-scale signals up to the Nyquist frequency. With internal functions similar to those of the ADS-946, this converter operates with inputs spanning ±2.75V. Operation requires ±5V supplies, and power dissipation is 1.85W. The commercial- and military-temperature-range versions cost $697 and $836 (100), respectively.
—by Bill Schweber

Datel Inc, Mansfield, MA. (508) 339-3000, ext 227