The GX9764 Digital-to-Analog Converter (DAC), compatible with the AD9764, is applied in ADSL/HFC modems.

ADSL/HFC modems primarily achieve asymmetric data transmission over telephone lines, enabling precise conversion between digital signals and RF/IF analog signals. The linearity, dynamic range, and noise immunity of the DAC in the transmit chain determine signal transmission fidelity. GXSC‘s single-channel 14-bit 125MSPS DAC fully meets ADSL/HFC transmission requirements. Packaged in a plastic TSSOP28, it is compatible with the AD9764.

The GX9764, a 14-bit resolution, wideband high-performance, low-power CMOS DAC, is specifically designed for medium-to-high-speed communication applications. It delivers exceptional AC and DC performance while supporting update rates up to 125 MSPS. Manufactured using advanced CMOS technology with a segmented current source architecture, the GX9764 minimizes spurious components and enhances dynamic performance, aligning perfectly with ADSL/HFC modems‘ transmission requirements for “high fidelity, wide dynamic range, and multi-band adaptability.”

The GX9764 integrates an edge-triggered input latch and a 1.25V temperature-compensated bandgap reference to deliver a complete monolithic DAC solution. Its differential current outputs support both single-ended and differential applications. In differential mode, matching between the two current outputs impacts dynamic performance. Current outputs can connect directly to output resistors to provide two complementary single-ended voltage outputs, or feed directly into transformers.

The on-chip reference and control amplifier deliver maximum precision and flexibility, capable of being driven by either the internal reference voltage or various external reference voltages. The internal control amplifier offers a wide adjustment range (>10:1), allowing the device‘s full-scale current to be adjusted between 2mA and 20mA while maintaining excellent dynamic performance. This enables operation at lower power levels or adjustment within a 20dB range to provide additional gain variation.

GX9764 Product Advantages:

Single-channel 125MSPS DAC

14-bit resolution

Differential current output: 2mA to 20mA

Power consumption: 88mW (@3.3V)

Single 3.3V supply

On-chip 1.25V reference

Edge-triggered latch

Sampling rate: 125 MSPS

Static performance: DNL -1.5/+1.5 LSB, INL -2.5/+2.5 LSB

Dynamic performance:

- fclock=25 MSPS, fout=1.00 MHz SFDR=72 dBc

- fclock=50 MSPS, fout=1.00 MHz SFDR=65 dBc

-fclock=50MSPS, fout=2.51MHz SFDR=70dBc

-fclock=50MSPS, fout=5.02MHz SFDR=74dBc

-fclock=50MSPS, fout=20.2MHz SFDR=65dBc