Analog Devices is tackling basestation inefficiency with its latest digital to analog converters (DACs). At a third of the size of competing transmit DACs, the eight latest additions to ADI's TxDAC range also acknowledge that for wireless infrastructure, space is as important an issue as power.
The AD971x series has been designed for basestations and battery-powered radios, whilst the AD911x series is optimised for low-cost cellular basestations. Both series boast significant reductions in power consumption. Dissipating 220mW at maximum sample rate, the AD911x devices consume 40 percent less power than competing DACs, while achieving 85-dB SFDR to 10MHz – 10dB better SFDR (spurious-free dynamic range) performance than other devices in its class. Meanwhile, the AD971x devices, with 2mA full-scale output current, are said to consume 70 percent less power than competing solutions.
The new TxDACs are dual 14, 12, 10 and 8bit converters with sample rates up to 125MS/s (mega-samples-per-second). For the AD971x, full-scale current is adjustable from 1 to 4 mA, whilst for the AD911x it is adjustable between 4 and 20 mA. They share a single, pin-compatible architecture and common software code.
Other features include an internal calibrator, an internal voltage reference, on-chip load and common-mode resistors, and a pair of auxiliary DACs that can be used for generating control voltages or for system calibration. The devices come in a 6mm – 6mm, 40-lead LFCSP (lead-frame chip-scale package) and are now available in volume.