A multiphase direct-digital-synthesis sinewave generator for high-accuracy impedance comparison

We will report on the realization and characterization of a dual-phase sinewave generator based on the direct-digital-synthesis technique, by using the new Analog Devices direct-digital-synthesizer AD9854. Particular attention is paid on the stability and accuracy of the sinewave amplitude in order to achieved high-accuracy impedance measurements. The sinewave frequency can be tuned in the range from 16 Hz to 16 kHz with a resolution < 10 mu Hz and with a relative frequency stability of 10(-8), whereas the sinewave long-term amplitude stability is better than 10(-5) around the 10 V nominal. Signal amplitude, frequency, and phase are monitored and set by means of a personal computer.