A precise two-channel digitally synthesized AC voltage source for impedance metrology

A two-channel AC voltage source based on digital synthesis is reported. We present measurement results of some of the key properties at 1 kHz with applications like digital impedance bridges in mind. Measurements show that amplitude ratio of the channels has a stability (Allan standard deviation) of one part in 10
⁸
for a 30 min measurement. The phase difference between the channels is also stable within 0.1 μrad.