Dynamic Resistance Delta-Sigma Modulator for Fast Low-Noise Readout
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Solution Overview
Problem
Conventional Delta-Sigma modulators used in analog-to-digital converters for digital pixel image sensors face challenges in achieving high-speed integration and high signal handling due to limitations in sample rate, power consumption, and noise susceptibility, particularly when dealing with low impedance detectors and large arrays of modulators.
Innovation Solution
The introduction of a dynamic resistance element (DRE) in the Delta-Sigma modulator circuit, which allows for variable resistance based on voltage differences, enables efficient charge transfer and reduces power consumption by eliminating the need for active amplifiers, thereby enhancing integration speed and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional Delta-Sigma modulators are used in analog-to-digital converters for digital pixel image sensors, then high dynamic range can be achieved through oversampling and filtering, but the sample rate is limited and power consumption increases
Solution Approach 1:
The patent extracts and eliminates the active amplifier component from the Delta-Sigma modulator circuit, replacing it with a dynamic resistance element. This removal of the power-intensive active amplifier directly reduces power consumption while maintaining the modulator's core functionality through the voltage-dependent resistance characteristics of the DRE.
Solution Approach 2:
The patent changes the operational parameter from active amplification to passive dynamic resistance modulation. The DRE's resistance varies with applied voltage, enabling the circuit to achieve signal processing functionality through parameter change rather than continuous active power consumption, thus improving energy efficiency.
2Power
If active amplifiers are used in Delta-Sigma modulators, then signal amplification can be achieved, but power consumption increases and integration speed is limited
Solution Approach 1:
The patent substitutes the mechanical/electronic active amplifier system with a field-effect-based dynamic resistance element. The DRE uses voltage-dependent electrical field effects to provide signal processing functionality without the power consumption and speed limitations of active amplifiers, achieving both amplification capability and faster integration.
3Reliability
If conventional modulator circuits are used, then basic ADC functionality can be achieved, but noise susceptibility increases particularly with low impedance detectors
Solution Approach 1:
The patent removes the active amplifier that introduces noise into the signal path, particularly problematic with low impedance detectors. By replacing it with a passive DRE, the circuit eliminates a major noise source while maintaining ADC functionality, thus improving reliability against noise without significantly increasing complexity.
4Productivity
If higher DSM clock frequencies are used, then integration speed improves, but power consumption and power supply spiking increase
Solution Approach 1:
The patent extracts and removes the active amplifier that causes power supply spiking at high clock frequencies. The passive DRE configuration eliminates the need for high-current switching operations that burden the power supply, enabling faster integration without the associated power supply noise and energy loss.
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
The DRE-DSM circuit achieves faster integration rates, lower power consumption, and reduced noise, allowing for higher DSM clock frequencies and ADC resolution while minimizing power supply spiking and modulator noise, thus improving the dynamic range and efficiency of image sensors.
Implementation Method 1
a dynamic resistance element electrically coupled between the first and third nodes for receiving a current input signal from the third node, wherein the dynamic resistance element is configured to have a variable resistance that changes in accordance with a voltage difference across the dynamic resistance element
Data Source
AI summary
The present disclosure provides a delta-sigma modulator circuit for use in a pixelated image sensor or a readout integrated circuit. In one aspect, the modulator circuit includes a dynamic resistance element configured to have a variable resistance that changes in accordance with a voltage difference across the dynamic resistance element.