Abstract: A superconducting analog-digital converter in which at least one of the electrical feed lines or conductance lines is replaced by an optical feed line. Current input and output signals being converted or generated by optoelectronic and/or magneto-optical elements.

Abstract: A superconducting analog-to digital converter comprises an input line, a soliton generator, a phase sampler, and a decoder. The soliton generator includes a nonlinear transmission line and a gradient current source. The transmission line is a series of inductive links separated from a superconducting ground plane by Josephson junction. The gradient current source induces gradient pump currents that are inductively coupled into the transmission line. The gradient establishes a three-cycle soliton. A time-varying current input signal is inductively coupled to the transmission line so that the local pump current changes as a function of changes in the input signal. These changes cause the soliton to move, and thus change its phase, along the transmission line. Sixty-four comparators of the phase sampler track the phase of the soliton. The digital readout of the phase sampler is then decoded to determine the value of the signal input.

Abstract: The present invention is directed to dynamically adjusting the threshold of a magnetic flux sensitive comparator to permit matching of circuit elements for use in A/D converters. For example, comparator threshold variations can be adjusted or programmed to compensate for variations in device components such as resistors. By overcoming parameter matching problems, superconductive A/D converters designed in accordance with the present invention can provide relatively high bandwidth and sampling rates.

Abstract: A high-speed, high-resolution superconducting counting A/D converter providing greatly increased conversion speeds with a low device count. The superconducting counting A/D converter includes includes a double-junction SQUID quantizer and a bidirectional binary counter having n stages of floating four-junction SQUID flip-flops, where n is the number of bits of accuracy of the counter. The quantizer continuously tracks an analog signal, generating up-count and down-count voltage pulses of the same polarity on two different output lines for increasing and decreasing values of the analog current, respectively. The bidirectional binary counter algebraically counts the voltage pulses, increasing the binary count when up-count pulses are received and decreasing the binary count when down-count pulses are received. Several techniques for reading the contents of the bidirectional binary counter at the end of each sampling interval are also disclosed.

Abstract: A successive approximation analog to digital converter including at least one superconducting loop (FIG. 3-30; FIG. 8-68). Superconducting loops (61-64) may be used to store flux quanta used as reference levels in a digital to analog converter of the analog to digital converter. Alternatively, non-superconducting reference inductors (FIG. 3-38) can provide flux quanta reference levels. Switchable screens (34; 66) are interposed between the flux quanta stores and lobes (31; 74) in an addition/subtraction superconducting loop (30; 68). An analog signal is sampled and the corresponding magnetic flux coupled to a sensing lobe (32; 71) and concentrated at a flux concentrating lobe (33; 72). The reference fluxes are selectively coupled into the addition/substraction superconducting loop until a magnetometer (40;73) indicates zero net flux through the concentrating lobe, this corresponding to completion of the conversion.

Abstract: An analog-to-digital converter employing superconducting quantum interference devices (SQUID's) to produce countable voltage pulses at uniformly spaced quantization levels, the converter having multiple SQUID quantizers, each of which receives an identical analog signal current to be converter to digital form, and a bias current to provide an offset in the position of the quantization level for each quantizer. For a quantization current of .DELTA.i, the bias currents in each of 2.sup.n quantizers are 0, .DELTA.i/2.sup.n, 2.DELTA.i/2.sup.n, and so forth up to (2.sup.n -).DELTA.i/2.sup.n. The outputs of the quantizers are monitored in associated flip-flop circuits, the states of which are sampled and decoded to yield an n-bit output that can be combined with the output of a binary counter monitoring just one of the quantizers. The quantizers provide outputs that are effectively interleaved between adjacent quantization levels of a single quantizer.

Abstract: A superconducting current detecting circuit which comprises a reference current generation circuit for generating a reference current and a DC flux parametron circuit for comparing an input current to be detected with the reference current to thereby produce pulses in synchronism with an input excitation signal, the number of the pulses being varied in accordance with a difference between the input current and the reference current, the pulses having positive or negative values depending on the polarity of the difference, the reference current generation circuit having means for increasing or decreasing the reference current by a quantity corresponding to the number of the pulses in response to the polarity of the pulses so that reference current generation circuit produces the reference current which agrees with the input current.