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The design, manufacture and subsequent testing of a superconductive flash digitizer circuit utilizing niobium trilayer technology is presented. The device will be used in recording transient physical phenomena such as electromagnetic pulses. The superconductive flash digitizer is composed of a 6-bit flash analog-to-digital converter, on-chip switches for data acquisition control and a bank of acquisition shift-registers for on-chip memory.

The development of a 16-bit serial analog-to-digital converter (ADC) aimed at reducing the number of outputs originating from the chip is presented. The device is intended for producing a high-resolution ADC that is expected to have wide applications in areas such as readout electronics for infrared detectors. Extracting the serial ADC output with an optical fiber coupled to a laser diode results in a further reduction of the heat load and a stronger signal transmission.

A study was conducted on a single-chip digital superconducting quantum interference device (SQUID) magnetometer. Results show that an input analog SQUID determines the noise level and sensitivity in an optimized magnetometer chip. The chips can be used in high magnetic field environments without extensive magnetic shielding due to their wide dynamic range. External two-phase clock frequencies were used to determine the devices' slew rate.

Digital error-correction circuits for enhancing superconductive flash analog-to-digital converter (ADC) performance were designed, fabricated and tested. Threshold errors occur mostly in comparators coding the most significant bits since they are not sensitive to input signal and are subject to threshold misplacement and jitter. The new ADC architecture employs two comparators per bit and is free from threshold errors.

High bandwidth Josephson circuits were developed for interfacing the rapid single flux quantum (RSFQ) circuits' output to room temperature electronics. The RSFQ signal levels were amplified to voltage outputs in the 2-4 mV range using asynchronous direct current powered voltage driver circuits which were analyzed and tested for data rates of up to 8 Gb/s. Circuits integrated with drivers were successfully tested at low speed while shift registers integrated with voltage driver circuits were demonstrated at high-speed.

A time-to-digital converter was designed, fabricated and tested. The converter circuit features superconductive counters based on toggle flip-flops with destructive readout, pulse detectors, parallel-to-serial converters and shift registers. HYPRES' library of standard RSFQ cells was used for the implementation of the circuits in HYPRES' standard Nb process with a 1.0 kA/cm2 critical current density.

A new Rapid Single Flux Quantum (RSFQ) compatible design was compared to a superconducting quantum interference device wheel/Quantum Flux Parametron comparator. Both provide -0.5 ps threshold accuracy which enables the development of a flash analog-to-digital converter with six effective bits of resolution at 10 GHz input bandwidth. Results show that the RSFQ design has a faster and more flexible clocking scheme and a better signal-to-noise ratio than the comparator.

A flux-quantizing analog-to-digital converter is built using rapid single flux quantum elements. The converter features a single-junction voltage-biased front end that provides wide-dynamic-range hysteresis-free operation with fractional-flux-quantum least significant bit. The front end also enables the generation of high-linearity multibit differential code, allowing conversions with large oversampling ratio and effective resolution.

A digital superconducting quantum interference device (SQUID) that uses the oversampling delta-modulation technique is fabricated using a novel architecture. The device consists of a pickup coil, a SQUID amplifier, a feedback loop and edge-triggered latching comparators. It generates a sampling frequency which can suppress the quantization noise below the the SQUID intrinsic noise.

The linearity and dynamic range of flux-quantizing analog/digital converters (ADCs) were measured using a simple double-counter analog/digital architecture. Analog/digital converter chips fabricated using a standard niobium processing technology were used in the study. Results show that the flux-quantizing ADCs have excellent conversion properties and exhibit no evidence of nonlinearity.