Amplifier Offset Feedback Circuit Without a DA Converter
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Solution Overview
Problem
Existing amplifier circuitry with negative feedback amplifiers faces increased circuit area and power consumption due to the connection of a DA converter, which affects amplification accuracy and efficiency.
Innovation Solution
The amplifier circuitry incorporates a sampling circuitry, a quantizer, a differential amplifier, and a feedback capacitor, where the quantizer detects amplification errors and adjusts the offset of the operational amplifier to converge the inverting input terminal voltage to zero, eliminating the need for a DA converter and reducing circuit area and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a DA converter is connected to the output node of the negative feedback amplifier to control the input voltage to zero, then amplification accuracy is improved, but circuit area and power consumption increase
Solution Approach 1:
The patent extracts and removes the DA converter from the traditional negative feedback amplifier configuration. Instead of using a DA converter to control the input voltage to zero, the invention uses a simplified feedback mechanism where the output of the operational amplifier is directly fed back through a feedback capacitor to the inverting input terminal, eliminating the need for the DA converter and its associated circuit area
Solution Approach 2:
The patent uses a quantizer to detect the input voltage and generates a digital output code that represents the voltage level. This digital code is then used to control an offset current source that generates an offset voltage, creating a digital-controlled feedback system that replaces the analog DA converter while maintaining the essential feedback function
2Measurement precision
If a DA converter is connected to the output node of the negative feedback amplifier, then amplification accuracy is improved, but power consumption increases
Solution Approach 1:
The patent removes the power-consuming DA converter from the circuit and replaces it with a more energy-efficient digital-controlled offset mechanism. The quantizer and offset current source consume significantly less power than a DA converter while achieving the same feedback control objective
Solution Approach 2:
The patent replaces the analog DA converter mechanism with a digital control mechanism. The quantizer converts the analog input voltage to a digital code, which then controls the offset current source through digital logic circuits, substituting the mechanical/analog DA converter with a digital system that consumes less power
3Measurement precision
If high-performance differential amplifiers are used to improve amplification accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent employs a feedback mechanism where the output of the operational amplifier is fed back through a feedback capacitor to the inverting input terminal. This feedback loop automatically corrects errors and maintains amplification accuracy without requiring the operational amplifier itself to be of ultra-high performance, thereby reducing circuit complexity
Solution Approach 2:
The feedback system performs self-correction by automatically adjusting the offset voltage based on the detected input voltage. The quantizer detects the voltage level and the offset current source automatically generates the appropriate correction, making the system self-regulating without requiring complex external control circuits
Data Source
AI summary
Amplifier circuitry has sampling circuitry which samples an input voltage, a quantizer which quantizes an output voltage of the sampling circuitry and outputs an output code, a differential amplifier which amplifies a differential voltage between the output voltage of the sampling circuitry and a reference voltage and performs offset adjustment according to the output code of the quantizer, and a first capacitor which is connected between an output node of the differential amplifier and an output node of the sampling circuitry.