Delta-Sigma ADC Feedback Circuit Without Switch-Induced Offset
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Solution Overview
Problem
Existing delta-sigma modulation type A/D converters face challenges in achieving high-precision A/D conversion due to offset issues and require improvements in reducing offset errors.
Innovation Solution
A delta-sigma modulation type A/D converter configuration incorporating a capacitively coupled amplifier, a correlated double sampling type first integrator, and a second integrator, with a quantizer and D/A converters that feed back the output to the amplifier and integrators, allowing direct connection without switches and simplifying the feedback path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switches are used in the connection between the capacitively coupled amplifier and the first integrator, then signal routing can be controlled, but offset errors and sampling noise increase
Solution Approach 1:
The patent removes switches from the signal path between the capacitively coupled amplifier and the first integrator, extracting the harmful element (switch) that causes offset errors and sampling noise. The direct connection eliminates the switch-induced problems while maintaining the necessary signal routing through the continuous feedback path.
Solution Approach 2:
The patent introduces a direct wire connection as an intermediary element between the amplifier output and integrator input, replacing the switch-based connection. This direct connection serves as a clean signal path that does not introduce offset errors or sampling noise, while still allowing the feedback signal to be transmitted to the integrator.
2Ease of operation
If switches are used in the feedback path, then feedback control can be implemented, but the circuit complexity and offset errors increase
Solution Approach 1:
The patent removes switches from the feedback path, extracting the complexity and offset errors associated with switch-based feedback control. The feedback control is maintained through the continuous connection from the integrator output back to the amplifier input, eliminating the need for switch-based routing.
3Measurement precision
If continuous amplification and integration are performed without switches, then offset errors are reduced, but the circuit requires direct connection without switching components
Solution Approach 1:
The patent uses a direct wire connection as an intermediary between the amplifier and integrator, providing a continuous signal path that enables high-precision A/D conversion without introducing offset errors. This direct connection simplifies the circuit implementation by eliminating the need for switch-based routing while maintaining the necessary signal transmission.
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 configuration enables high-accuracy A/D conversion while reducing offset errors by amplifying analog input signals continuously and integrating them without saturation, simplifying the circuit and reducing the influence of sampling noise.
Implementation Method 1
a capacitively coupled amplifier having a sampling capacitor, a feedback capacitor, and an amplifier
Implementation Method 2
the analog differential signal amplified by the capacitive differential amplifier circuit is integrated by an integrator
Data Source
AI summary
A delta-sigma modulation type A/D converter includes: a capacitively coupled amplifier having a sampling capacitor, a feedback capacitor, and an amplifier; a correlated double sampling type first integrator as a first-stage integrator, which is connected to the capacitively coupled amplifier without a switch; a second integrator arranged after the first integrator; a quantizer arranged after the second integrator and quantizing an output of the second integrator; and an D/A converter that D/A-converts an output of the quantizer and feeds back to any one of the capacitively coupled amplifier, the first integrator, and the second integrator.