Single-Bit Delta-Sigma Modulator Gain Control for Auto-Ranging
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Solution Overview
Problem
Single-bit delta-sigma analog-to-digital converters face limitations in achieving high dynamic range without requiring additional circuit elements, particularly when dealing with analog input signals of high dynamic ranges.
Innovation Solution
An ADC with an automatic ranging feature, utilizing a single-bit delta-sigma quantizer that adapts the magnitude of the subtrahend signal based on the digital output, incorporating an integrator, threshold detector, feedback block, and range control circuit to adjust the subtrahend signal, preventing integrator saturation and enhancing dynamic range.
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 automatic gain control. The RCC adjusts the magnitude of the subtrahend signal based on the bitstream output, enabling the single-bit quantizer to adapt to different input signal levels and achieve high dynamic range without requiring additional quantizer circuitry
Solution Approach 2:
The patent introduces an automatic gain control mechanism as an intermediary between the single-bit quantizer and the output. The range control circuit acts as a mediator that processes the bitstream and adjusts the feedback subtrahend signal magnitude, enabling the simple single-bit quantizer to achieve the performance of complex multi-bit quantizers
2Measurement precision
If the magnitude of the subtrahend signal is increased to handle high dynamic range inputs, then measurement precision is improved, but the integrator may saturate causing loss of information
Solution Approach 1:
The patent employs feedback by using the quantizer output bitstream to control the automatic gain control circuit. The RCC monitors the bitstream and adjusts the subtrahend signal magnitude in real-time, creating a feedback loop that prevents integrator saturation while maintaining high dynamic range capability
Solution Approach 2:
The patent makes the subtrahend signal magnitude dynamic rather than fixed. The automatic gain control allows the system to adapt the feedback signal strength based on the current input signal level, enabling the integrator to handle both large and small signals without saturation while maintaining precision
Data Source
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AI summary
The invention relates to an analog-to-digital converter, ADC, based on single-bit delta-sigma quantization. The ADC comprises an integrator (INT), a threshold detector (TD), a feedback block (FBB), a range control circuit (RCC) and an output processing block (OPB). 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.