Space-saving, low-power DOCSIS 3.0-compliant RF D/A converter

October 16, 2012 // By Paul Buckley
Analog Devices has introduced two RF D/A converters that are able to synthesise the entire downstream (transmit) cable spectrum from a single D/A converter port.

Supporting data rates up to 2.8 GSPS, the single-channel, 14-bit AD9129 and 11-bit AD9119 RF D/A converters allow cable operators to reduce the total system power and component count of CATV (CMTS)  infrastructure equipment, simplify system design, and lower total bill of material costs.

The RF D/A converters support from one to as many as 158 CATV carriers and include an optional 2x interpolation filter that reduces output filtering complexity by effectively increasing the D/A converter update rate by a factor of two. In its Mix-Mode super-Nyquist operation, the AD9129 can reconstruct spectrally-pure RF carriers in the 2nd and 3rd Nyquist zones, eliminating a mixing stage while still maintaining  dynamic range at up to 4.2 GHz.

The AD9129 RF D/A converter enables industry leading direct RF synthesis performance with minimal loss of output power across its output spectrum. The device also enables dual-edge clocking operation, effectively increasing the converter update rate to 5.6 GSPS when configured for Mix-Mode or 2x interpolation mode. Its high dynamic range and bandwidth enable multi-carrier generation up to 4.2 GHz. The device dissipates 1.1 W at the full 2.8-GSPS D/A converter update rate.

The AD9129 includes a dual-port, source-synchronous LVDS (low-voltage differential signalling) interface that simplifies the data interface to a host FPGA or ASIC. On chip DLLs (delay-locked loops) optimise timing between different clock domains, while an SPI (serial peripheral interface) is used to configure the AD9129 and monitor the status of read-back registers.

Samples of the AD9129 RF D/A converter are available now with production release schedule for November 30, 2102.  The device is packaged in a 160-Ball CSP-BGA.

Samples of the AD9119 RF D/A converter are available now with production release schedule for November 30, 2102.  The device is packaged in a 160-Ball CSP-BGA.

www.analog.com/AD9129
www.analog.com/AD9119