Single-Bit Delta-Sigma ADC Auto-Ranging for High Dynamic Range
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Solution Overview
Problem
Single-bit delta-sigma quantizers face limitations in achieving high dynamic range analog-to-digital conversion, particularly with signals of high dynamic ranges, due to the need for additional circuit elements in multi-bit delta-sigma quantizers, which increases energy consumption and complexity.
Innovation Solution
An analog-to-digital converter (ADC) with an automatic ranging feature, utilizing a single-bit delta-sigma quantizer that adapts the magnitude of the subtrahend signal based on digital output information, incorporating an integrator, threshold detector, feedback block, and range control circuit to adjust the subtrahend signal, thereby avoiding saturation and achieving high dynamic range conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multi-bit delta-sigma quantizers are employed to overcome resolution limitations, then measurement precision is improved, but device complexity increases due to additional circuit elements
Solution Approach 1:
The patent changes the parameter of subtrahend signal magnitude dynamically through auto-ranging. The range control circuit adjusts the magnitude of the subtrahend signal based on the bitstream output, allowing a single-bit quantizer to adapt its effective resolution and dynamic range without requiring additional quantizer circuitry. This resolves the contradiction by achieving high measurement precision through parameter adaptation rather than through increased quantizer bit-depth.
2Measurement precision
If multi-bit delta-sigma quantizers are used to achieve high dynamic range, then measurement precision is improved, but use of energy increases due to additional circuit elements
Solution Approach 1:
The patent employs dynamic parameter change by adjusting the subtrahend signal magnitude according to the input signal level. The range control circuit monitors the bitstream and modifies the subtrahend magnitude accordingly, enabling high dynamic range measurement with a single-bit quantizer that consumes less power than multi-bit alternatives. This resolves the energy-dynamic range contradiction through adaptive parameter control.
3Device complexity
If the magnitude of the subtrahend signal is fixed, then device complexity is reduced, but adaptability decreases for signals with high dynamic ranges
Solution Approach 1:
The patent introduces dynamics into the system by making the subtrahend signal magnitude adjustable rather than fixed. The range control circuit dynamically adapts the subtrahend magnitude based on the bitstream characteristics, allowing the single-bit quantizer to maintain optimal performance across a wide dynamic range. This resolves the contradiction by implementing minimal dynamic control logic that provides high adaptability without significant complexity increase.
Data Source
AI summary
An analog-to-digital converter (ADC) is based on single-bit delta-sigma quantization. The ADC includes an integrator, a threshold detector, a feedback block, a range control circuit and an output processing block. The ADC is configured to, based on its own generated digital bitstream, adjust the magnitude of a subtrahend signal in order to achieve autonomous auto-ranging of the ADC during the integration time of a measurement. In particular, the auto-ranging allows for the efficient conversion of an analog input signal with high dynamic range, for example ambient light, to a digital output signal.