Differential Current Sampling Circuit With Low-Power Feedback
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Solution Overview
Problem
Current current sampling circuits face challenges in high integration density and high power consumption, making them unsuitable for large-scale applications and energy-efficient designs.
Innovation Solution
A current sampling circuit utilizing a full differential common mode negative feedback circuit with a proportional current output circuit, implemented with LDMOS and PMOS transistors, which calculates and outputs proportional currents to a full differential common mode negative feedback network for stable and accurate sampling, reducing power consumption by using microamp bias currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional current sampling circuit with operational amplifier and feedback circuit is used, then accurate current sampling is achieved, but power consumption increases and integration density decreases
Solution Approach 1:
The patent extracts and eliminates the operational amplifier from the traditional feedback circuit, retaining only the essential feedback transistors (M4) and resistors (R1, R2) to achieve current sampling. This extraction removes the high-power component while preserving the core sampling function through the remaining feedback mechanism.
Solution Approach 2:
The patent replaces the expensive, power-hungry operational amplifier with a simpler, lower-cost transistor-based feedback circuit. The simplified circuit uses standard transistors and resistors that consume significantly less power while achieving comparable sampling accuracy through the feedback mechanism.
2Measurement precision
If a traditional current sampling circuit with operational amplifier is used, then accurate current sampling is achieved, but device complexity and area increase
Solution Approach 1:
The patent extracts and removes the operational amplifier from the circuit, keeping only the minimal feedback components (transistor M4 and resistors R1, R2) necessary for accurate current sampling. This dramatically simplifies the circuit structure while maintaining sampling precision through the feedback mechanism.
Solution Approach 2:
Instead of using a complex operational amplifier to achieve feedback control, the patent inverts the approach by using a simple transistor-based feedback circuit that achieves the same control function with fewer components and less complexity.
3Measurement precision
If a traditional current sampling circuit with operational amplifier is used, then accurate current sampling is achieved, but integration density decreases
Solution Approach 1:
The patent extracts and eliminates the operational amplifier, which occupies significant area, retaining only the essential feedback transistor M4 and resistors R1, R2. This extraction dramatically reduces the circuit area while preserving accurate current sampling through the simplified feedback path.
Data Source
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AI summary
Disclosed is a current sampling circuit including a proportional current output circuit and a full differential common mode negative feedback circuit, specifically the proportional current output circuit is configured to calculate a current output from a power device according to a preset proportion to obtain a first proportional current and a second proportional current, and to output the first proportional current and the second proportional current to the full differential common mode negative feedback circuit; and the full differential common mode negative feedback circuit is configured to shunt respectively the first proportional current and the second proportional current using a full differential common mode negative feedback network with a bias current in microamps to obtain a first sampling current and a second sampling current, and to output constantly the first sampling current and the second sampling current. Further disclosed is a current sampling method.