AD9764:  14-Bit, 100 MSPS+ TxDAC® D/A Converter

The AD9764 is the 14-bit resolution member of the TxDAC® series of high performance, low power CMOS digital-to-analog converters (DACs). The TxDAC®; family, which consists of pin compatible 8-, 10-, 12-, and 14-bit DACs, is specifically optimized for the transmit signal path of communication systems. All of the devices share the same interface options, small outline package and pinout, providing an upward or downward component selection path based on performance, resolution and cost. The AD9764 offers exceptional ac and dc performance while supporting update rates up to 125 MSPS.

The AD9764’s flexible single-supply operating range of 2.7 V to 5.5 V and low power dissipation are well suited for portable and low power applications. Its power dissipation can be further reduced to a mere 45 mW with a slight degradation in performance by lowering the full-scale current output. Also, a power-down mode reduces the standby power dissipation to approximately 25 mW.

The AD9764 is manufactured on an advanced CMOS process. A segmented current source architecture is combined with a proprietary switching technique to reduce spurious components and enhance dynamic performance. Edge-triggered input latches and a 1.2 V temperature compensated bandgap reference have been integrated to provide a complete monolithic DAC solution. Flexible supply options support +3 V and +5 V CMOS logic families.

The AD9764 is a current-output DAC with a nominal full-scale output current of 20 mA and > 100 k ohm output impedance. Differential current outputs are provided to support single-ended or differential applications. Matching between the two current outputs ensures enhanced dynamic performance in a differential output configuration. The current outputs may be tied directly to an output resistor to provide two complementary, single-ended voltage outputs or fed directly into a transformer. The output voltage compliance range is 1.25 V.

The on-chip reference and control amplifier are configured for maximum accuracy and flexibility. The AD9764 can be driven by the on-chip reference or by a variety of external reference voltages. The internal control amplifier, which provides a wide (>10:1) adjustment span, allows the AD9764 full-scale current to be adjusted over a 2 mA to 20 mA range while maintaining excellent dynamic performance. Thus, the AD9764 may operate at reduced power levels or be adjusted over a 20 dB range to provide additional gain ranging capabilities.

The AD9764 is available in a 28-lead SOIC package. It is specified for operation over the industrial temperature range.