Electronic Design and Family Site

Schematics for Experiments in DDS

This page contains the schematics for basically 2 types of Direct Digital Synthesis (DDS) variable frequency oscillators (VFOs):  a relatively basic, but wideband DDS, AD9850, and a much more versatile and even wider-band, AD9854.  The AD9854 can produce 2 quadrature outputs which is useful or driving phased direct-conversion receivers.

Both of these "oscillators" are controlled by a PIC Microcontroller, 18F2520.  They use an rotary encoder for variability, and LCD for frequency and other display.

The AD9854-based RF Board

Schematic of the analog portion of the AD9854-based DDS Oscillator

The AD9854-based Digital Board Schematic

Schematic of the Digital portion of the AD9854-based DDS Oscillator

AD9850-Based Complete VFO

Schematic of the complete AD9850-based DDS Oscillator

Complete VFO using Commercial AD9850 Module

Schematic of a AD9850-based DDS Oscillator using a commercial plug-in module