AD9774AS

Digital To Analog Converters Overview

The AD9774AS is a single-supply, oversampling 14-bit digital-to-analog converter (DAC) from Analog Devices. It integrates a 4× digital interpolation filter and a PLL clock multiplier to support input data rates up to 32 MSPS at 5 V operation. The device generates an internal DAC update rate of 128 MSPS, enabling waveform reconstruction bandwidths up to 13.5 MHz. Key electrical specifications include a typical Spurious-Free Dynamic Range (SFDR) of 77 dBc at 5 MHz output, 12 effective number of bits (ENOB) at 1 MHz, and a full-scale differential current output adjustable between 2 mA and 20 mA. It operates on a single supply voltage ranging from 2.7 V to 5.5 V.

Digital To Analog Converters Feature Summary

• Integrated 4× digital interpolation filter with two-stage halfband FIR topology suppresses in-band images by >69 dB.
• On-chip Phase-Locked Loop (PLL) clock multiplier generates synchronized 1×, 2×, and 4× clocks from external reference.
• Differential current outputs configurable for single-ended or differential topologies with 2 mA to 20 mA full-scale range.
• Includes temperature-compensated 1.20 V bandgap reference and edge-triggered CMOS input latches.

Digital To Analog Converters Applications

• Communication transmit channels
• Wireless base stations
• ADSL/HFC modems
• Direct Digital Synthesis (DDS)

Digital To Analog Converters Procurement Notes

Verify the package designation matches the 44-lead MQFP (Metric Quad Flatpack) configuration specified for the AD9774AS model. Confirm that the operating environment remains within the industrial temperature range of -40°C to +85°C. Ensure power supply decoupling and ESD precautions are implemented during handling, as the device is sensitive to electrostatic discharge.

Digital To Analog Converters Selection Notes

Select this component when high dynamic range and low analog reconstruction filter complexity are required. The integrated 4× interpolation filter significantly reduces the burden on external analog filters by pushing image frequencies higher. It is suitable for applications requiring precise phase synchronization across multiple devices via the shared PLL architecture. Consider the power dissipation implications, as nominal consumption reaches 1125 mW at 5 V supplies.

Digital To Analog Converters Part Context

The AD9774AS belongs to the TxDAC+ family of high-performance, low-power CMOS digital-to-analog converters. This series is optimized for communication system transmit signal paths, offering pin-compatible options across various resolutions. The AD9774 specifically addresses waveform reconstruction needs where exceptional dynamic range and simplified filtering are critical design constraints.

Digital To Analog Converters Replacement Considerations

Publicly confirmed substitute part numbers are not available in the provided documentation. Evaluate alternative models based on resolution, update rate, and package compatibility if direct substitution is required.

Digital To Analog Converters FAQ

How does the AD9774 reduce the complexity of the analog reconstruction filter?

The device integrates a 4× digital interpolation filter that multiplies the input data rate by four. This pushes the first image frequency further away from the fundamental signal and suppresses original in-band images by more than 69 dB, thereby relaxing the transition band requirements for the external analog filter.

What is the maximum input data rate supported by the AD9774AS?

The AD9774AS supports a maximum input data rate of 32 MSPS when operated with a DVDD of 5 V. At 3 V operation, the maximum input data rate is reduced to 25 MSPS.

Can the AD9774 be used with TTL logic levels?

Yes, the device can accommodate TTL logic levels by reducing the digital supply voltage (DVDD). The edge-triggered input latches interface readily with both CMOS and TTL families depending on the selected supply voltage.