Fluxon Amplifier Subranging ADC for Cryogenic Dynamic Range
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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 superconductor technology and the impracticality of semiconductor amplifiers at cryogenic temperatures.
Innovation Solution
A subranging ADC architecture using a distributed digital fluxon amplifier that integrates functions of integration, filtering, and flux subtraction, along with a Phase Modulation Demodulation (PMD) delta ADC design, allows for high-gain linear differential amplification and reduces the required gain factor, enabling a dynamic range extension of about 30-35 dB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If semiconductor amplifiers are used to provide high-gain linear amplification in superconductor ADCs, then the dynamic range can be increased, but the amplifiers become impractical at cryogenic temperatures
Solution Approach 1:
The patent changes the temperature parameter from cryogenic (where semiconductor amplifiers fail) to elevated temperatures (e.g., 77K or higher) where superconducting materials can operate. This parameter change enables the use of superconducting amplifiers that provide high-gain linear amplification without the reliability issues of semiconductor devices at cryogenic temperatures, thereby extending the dynamic range of the ADC.
2Measurement precision
If subranging ADC architecture is used to extend dynamic range, then the effective number of bits increases, but the device complexity increases due to multiple ADCs and inter-range processing
Solution Approach 1:
The patent merges multiple functions (amplification, integration, filtering, and flux subtraction) into a single superconducting amplifier device. This consolidation achieves the dynamic range extension of a subranging ADC architecture while reducing device complexity by eliminating the need for separate coarse and fine ADCs and their associated inter-range processing circuitry.
Solution Approach 2:
The superconducting amplifier is designed to perform multiple functions simultaneously: it provides high-gain linear amplification, performs integration of the analog input signal, applies filtering to remove quantization noise, and executes flux subtraction to generate the residue signal. This multi-functionality achieves subranging ADC performance with a single device, reducing overall system complexity.
3Shape
If distributed digital fluxon amplifier is used for high-gain linear differential amplification, then the gain factor is reduced and dynamic range is extended, but the manufacturing precision requirements increase
Solution Approach 1:
The distributed digital fluxon amplifier employs feedback mechanisms where the output of each stage is fed back to adjust and linearize the transfer function. This feedback control compensates for manufacturing variations and non-linearities in the Josephson junctions and other superconducting components, thereby reducing the impact of manufacturing precision limitations while achieving high-gain linear differential amplification and extended dynamic range.
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 improved signal processing capabilities, increasing the effective number of bits and reducing noise and nonlinearity, resulting in improved signal-to-noise ratio (SNR) and spur-free dynamic range (SFDR).
Implementation Method 1
A flux quantizer based on a Josephson junction releases the flux in the form of single-flux-quanta voltage pulses
Implementation Method 2
A distributed digital fluxon amplifier that integrates functions of integration, filtering, and flux subtraction
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.