new 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 exceptional dynamic range at up to 4.2 GHz.
“The AD9129 RF D/A converter utilises ADI’s patented quad-switch architecture to synthesise the full DC-to-1.4 GHz baseband output spectrum, which will greatly simplify and improve downstream DOCSIS 3.0-compliant transmitter design,” said Carlton Lane, marketing manager, High-speed D/A Converter group, Analog Devices. “This D/A converter’s new level of performance and functionality enables cable infrastructure equipment manufacturers to implement the complete downstream signal chain in a smaller footprint, at one-third the power, and using fewer signal chain components. These are all important design considerations in today’s CMTS service environment.”
More About the AD9129 14-bit RF D/A Converter
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 only 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.
AD9129/19 Single-channel D/A Converters Features and Benefits:
• D/A converter update rate of up to 5.6 GSPS
• Direct RF synthesis @ 2.8 GSPS data rate
o DC-to-1.4 GHz in baseband mode
o DC-to-1.0 GHz in 2X interpolation mode
o 1.4-to-4.2 GHz in Mix-Mode
• 1 to 158 DOCSIS 3.0 carriers: 8 QAM carrier ACLR = > 69 dBc
• By-passable 2x interpolation filters
• Single/multi-carrier IF or RF synthesis
• Low power: 1.1 W @ 2.8 GSPS (1.3 W @ 5.6 GSPS)