Westinghouse Electric Corporation

Donald L Miller

John Xavier Przybysz

Eric H Naviasky

Joonhee Kang

A bandpass sigma-delta modulator for an analog-to-digital converter is provided in which an RLC circuit connected to the input analog signal is resonant at an intermediate frequency. A Josephson junction connected to the RLC circuit receives the current flowing through the RLC circuit. The Josephson junction emits a voltage pulse which reduces the RLC circuit current when the current in the Josephson junction exceeds its critical current. Selected multiples of the voltage pulse generated by the Josephson junction are fed back to the RLC circuit. A digital output is generated from the voltage pulses generated by the Josephson junction to complete the analog-to-digital conversion of the input signal.

Bandpass sigma-delta modulator for analog-to-digital converters

A spur-free sigma delta modulator analog-to-digital converter for converting an analog input signal to a digital output signal is provided. A race Josephson junction is provided between the pulse generator and the integrating inductor. The race Josephson junction emits a voltage pulse in response to every sampling pulse. This voltage pulse kills any retained persisting current in the integrating inductor. By adding the race Josephson junction, nonlinearities in the converter are eliminated. A multiple flux quanta feedback generator for creating a multiple digital pulse feedback in response to an input signal is provided. A quantizer connected to the input inductor produces a pulse when the current produced by the input inductor exceeds a predetermined amount. A splitter is connected to the quantizer for producing output pulses. In order to produce 2.sup.n output pulses, 2.sup.n -1 splitters are required. Each of the splitters produces two output pulses in response to a single pulse produced by the quantizer. Each of the 2.sup.n output pulses drives one of 2.sup.n feedback pulse generators. Each of the feedback pulse generators is connected to one of the output pulses to produce 2.sup.n +1 quanta feedback which is fed back to the input inductor.

Spur-free sigma-delta modulator and multiple flux quanta feedback

A serial multiplier for multiplying two n-bit numbers is provided in which a shift register having a total of n destructive read out cells contains a separate bit of a first multiplicand in each cell. A string of (2n-1) non-destructive read out cells is provided to receive the second multiplicand. Each of the first n cells of the string of non-destructive readout cells contain a separate bit of the second multiplicand. Each bit of the first multiplicand is serially multiplied with the series of bits of said second multiplicand. After each such multiplication, each bit of the second multiplicand is moved to the next adjacent cell. The partial product of the multiplication is stored in a string of 2n T flip-flop cells. Each of the T flip-flop cells has a carry path to the next adjacent T flip-flop cell. Timing means are provided to regulate and initiate the multiplication.

Single-flux-quantum multiply-accumulator

A two-loop superconducting sigma-delta analog-to-digital converter includes a first superconducting inductor to which the analog signal is applied. A resistor converts to current in the first inductor to a voltage which is applied to a second superconducting inductor. The current in the second inductor, which increases quadradically with time, is applied to an overdamped Josephson junction which kicks back a single quantum voltage pulse each time its critical current is exceeded. This pulse reduces the current in the second inductor and serves as a digital ONE output. The pulses are also applied to an underdamped Josephson junction in a feedback pulse generator which latches at its gap voltage for the remainder of a half cycle of an ac bias current. This provides a voltage source for the primary of a superconducting transformer having a mutual inductance which produces sufficient flux in the secondary to cause a SQUID to generate in response to each pulse from the quantizer a selected number of feedback pulses which are applied to the first inductor.

Two loop superconducting sigma-delta analog-to-digital converters

A superconducting sigma-delta analog-to-digital converter utilizes a superconducting inductor as the integrator and a Josephson junction connected in series between the inductor and ground as the quantizer. A SQUID generates sampling pulses at a selected GHz frequency which add to the inductor current flowing through the Josephson junction. When the combined current through the Josephson junction exceeds the critical current of the Josephson junction, a voltage pulse is generated which kicks back into the inductor to reduce the inductor current. The voltage across the Josephson junction is, therefore, a one bit digital representation of the analog signal. This one bit digital signal is converted to a multi-bit digital signal preferably by a decimator having superconducting circuits which reduce the frequency of the multi-bit digital signal to a frequency which can be further processed by semiconductor processors. Preferably, a weighting function is utilized in a conversion to improve accuracy.

Superconducting sigma-delta analog-to-digital converter

The present invention is directed to a light-triggered thyristor having a high di/dt, high dv/dt, and high photosensitivity. The thyristor has a three-stage cathode emitter gating structure with integrated current limiting resistors. The current limiting resistors are defined by moats etched in the cathode base region. The moats also cause a 'turn-on ' current to flow through substantially all of the cathode base region.

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Penn Township, Westmoreland County, PA, United States of America

Donald L Miller