Inventors:
Quentin P. Herr - Ellicott City MD, US
Aaron A. Pesetski - Gambrills MD, US
John X. Przybysz - Severna Park MD, US
Donald L. Miller - Export PA, US
Assignee:
Northrop Grumman Systems Corporation - Los Angeles CA
International Classification:
H03M 3/00
Abstract:
A second order superconductor delta-sigma analog-to-digital modulator having an input for receiving an analog signal, a first integrator coupled to the input, a second integrator cascaded with the first integrator, and a quantum comparator digitizing output from the second integrator reduces quantization noise by providing matched quantum accurate DACs in a feedback loop between output from the quantum comparator and input to the first integrator. The matched quantum accurate feedback DACs produce identically repeatable voltage pulses, may be configured for multi-bit output, may be time-interleaved to permit higher clocking rates, and may be employed in a balanced bipolar configuration to allow inductive input coupling. Bipolar feedback is balanced when gain of a first DAC exceeds gain of a matched, opposite polarity DAC by the amount of implicit feedback from the comparator into the second integrator.