AD9854 DIRECT DIGITAL SYNTHESIZER

Introduction

This evaluation board supports the AD9854 DDS devices. When referenced to an accurate clock source, the AD9854 generates a highly stable, frequency, phase and amplitude programmable sine and cosine outputs that can be used as an agile L.O. in communications, radar, and many other applications. The AD9854's innovative high-speed DDS core provides a 48-bit frequency tuning word, which results in an output tuning resolution of 1 micro-Hertz, for a 300 MHz internal reference clock input. The AD9854's circuit architecture allows the generation of simultaneous quadrature outputs at frequencies up to 150 MHz, which can be digitally tuned at a rate of up to 100 million new frequencies per second. The (externally filtered) sine wave output can be converted to a square wave by the internal comparator for agile clock generator applications. The device provides 14-bits of digitally-controlled phase modulation and single-pin PSK. The on-board 12-bit I ∓ Q DACs, coupled with the innovative DDS architecture, provide excellent wideband and narrowband output SFDR. The Q-DAC can also be configured as a user-programmable control DAC if the quadrature function is not desired. When configured with the onboard comparator, the 12-bit control DAC facilitates pulse-width modulation (PWM) and static duty cycle control, in the highspeed clock generator application. Two 12-bit digital multipliers permit programmable amplitude modulation, shaped on-off keying and precise amp-litude control of the quadrature outputs. The AD9854's programmable 4^x - 20^x REFCLK Multiplier circuit generates the 300 MHz clock internally from a lower frequency external reference clock. This saves the user the expense and difficulty of implementing a 300 MHz clock source. Direct 300 MHz clocking is also accommodated with either single-ended or differential inputs. Single-pin conventional FSK and the enhanced spectral qualities of "ramped" FSK are supported. The AD9854 uses advanced .35 micron CMOS technology to provide this high level of functionality on a single +3.3 V supply.

Documentation

To view the AD9854 product data sheet or schematic, select the link below:

Software

To download the software, select the link below: