AC and DC bipolar voltage source using quantized pulses

We have developed an accurate bipolar voltage source for AC and DC metrology, based on the quantized pulses of Josephson junctions. The output voltage is a factor of 4-6 higher than the amplitude of previous unipolar waveforms; this is achieved by generating bipolar waveforms where arrays of junctions are driven with both a broadband two-level digital code and a sinusoidal frequency. We experimentally demonstrate two bipolar waveforms: a 5 kHz sine wave with /spl plusmn/18 mV peak amplitude and quantization noise power eight orders of magnitude below the power in the fundamental frequency, and a 3.5 kHz square wave with /spl plusmn/13 mV peak amplitude and even harmonics at -100 dB (carrier).