Distributed Fluxon Amplifier in Subranging Superconductor ADCs
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Solution Overview
Problem
Superconductor analog-to-digital converters (ADCs) face challenges in achieving high-gain linear amplification, which is essential for increasing their dynamic range, due to the lack of suitable high-gain amplifiers in superconducting technology and impedance mismatch with semiconductor amplifiers.
Innovation Solution
A distributed digital fluxon amplifier is introduced, which integrates functions like integration, filtering, and flux subtraction, and a subranging ADC design using two delta modulators with a fluxon amplifier and subtractor circuitry to achieve a dynamic range extension of about 30-35 dB, avoiding the need for high-gain analog amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If semiconductor amplifiers are used in superconductor ADCs, then gain can be achieved, but impedance mismatch occurs between semiconductor and superconducting components
Solution Approach 1:
The patent replaces semiconductor amplifiers with a superconducting digital fluxon amplifier that uses digital logic circuits (RSFQ logic) to achieve signal amplification. This substitution eliminates the impedance mismatch problem by using entirely superconducting components while maintaining the amplification function through digital processing rather than analog semiconductor amplification.
2Measurement precision
If high-gain analog amplifiers are used to extend dynamic range, then dynamic range increases, but device complexity and difficulty of implementation increase due to lack of suitable superconducting amplifiers
Solution Approach 1:
The patent replaces complex analog superconducting amplifiers with a digital fluxon amplifier based on RSFQ logic circuits. The digital approach uses counters, decoders, and digital-to-analog converters to achieve the amplification function, which is much easier to implement in superconducting technology and reduces overall device complexity.
Solution Approach 2:
The patent introduces a digital intermediary stage that converts the analog flux signal to digital form, processes it through digital logic circuits for amplification, and then converts it back to analog form. This digital intermediary simplifies the amplification process by avoiding the need for direct analog amplification in the superconducting domain.
3Measurement precision
If subranging ADC architecture is used to extend dynamic range, then dynamic range improves by 30-35 dB, but circuit complexity increases due to additional modulators and subtractor circuitry
Solution Approach 1:
The patent divides the ADC into two ranges: a coarse range handled by a first delta modulator and a fine range handled by a second delta modulator. This segmentation allows each modulator to operate within its optimized range, achieving extended dynamic range while managing complexity through functional division.
Solution Approach 2:
The patent extracts the most significant bits of the signal through the first delta modulator and subtracts this coarse representation from the input signal, leaving only the residue that needs to be processed by the second delta modulator. This extraction approach reduces the burden on the fine modulator and optimizes the overall system performance.
4Measurement precision
If quantization noise and nonlinearity are minimized to improve SFDR, then measurement accuracy improves, but this requires high-precision components that increase manufacturing difficulty
Solution Approach 1:
The patent uses digital processing techniques to correct quantization noise and nonlinearity effects, replacing the need for ultra-precise analog components. Digital filters and correction algorithms applied in the digital domain can achieve high SFDR performance without requiring extremely tight manufacturing tolerances on the superconducting components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the dynamic range of superconductor ADCs by providing high-gain linear differential amplification, reducing the required gain factor, and improving signal-to-noise ratio (SNR) and spur-free dynamic range (SFDR) through accurate cancellation of quantization noise and nonlinearity.
Implementation Method 1
Superconductor data converters are based on ideal quantization of magnetic flux in units of the flux quantum Φ0=h/2e=2.07 mV-ps
Implementation Method 2
RSFQ circuits transport these single-flux-quanta (SFQ) in voltage pulses of height ̃1 mV and pulsewidth ̃2 ps
Data Source
AI summary
Superconductor analog-to-digital converters (ADC) offer high sensitivity and large dynamic range. One approach to increasing the dynamic range further is with a subranging architecture, whereby the output of a coarse ADC is converted back to analog and subtracted from the input signal, and the residue signal fed to a fine ADC for generation of additional significant bits. This also requires a high-gain broadband linear amplifier, which is not generally available within superconductor technology. In a preferred embodiment, a distributed digital fluxon amplifier is presented, which also integrates the functions of integration, filtering, and flux subtraction. A subranging ADC design provides two ADCs connected with the fluxon amplifier and subtractor circuitry that would provide a dynamic range extension by about 30-35 dB.