MEASUREMENTS OF DYNAMIC RANGE AND LINEARITY OF FLUX-QUANTIZING A/D CONVERTERS

High-precision measurements of the linearity of a flux-quantizing ADC using a pair of 6-bit RSFQ counters have been made. The sensitivity and dynamic range of the ADC were 13.3 mu A/LSB and +/- 30 mA respectively (12 bits). The conversion curve was measured with an accuracy of +/- 7.5% of LSB within dynamic range of 9 bits and exhibited no evidence of nonlinearity. In addition, we have tested stand-alone flux quantizers with dynamic range up to 16 bits and a unidirectional 12-bit ADC which directly demonstrated a correct divide-by-2(12) operation with a 10 GHz 4 LSBs sinewave input signal (peak counting frequency in excess of 80 GHz).