Bandgap Reference Circuit With Base Current Redistribution
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Solution Overview
Problem
Existing bandgap reference voltage generating circuits have high temperature coefficients and require multiple test passes at different temperatures for trimming, which increases manufacturing costs and complexity.
Innovation Solution
A bandgap reference voltage generating circuit incorporating a Brokaw bandgap cell, tail resistor circuit, high-order curvature compensation current generating circuit, and IZTAT current sink circuit, with a base current redistribution circuit and high-order curvature compensation, achieving a temperature coefficient of ±3 ppm/C over a wide temperature and supply voltage range, using a single temperature trim.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional bandgap reference circuits are used, then the circuit structure is simple, but the temperature coefficient is high and multiple test passes at different temperatures are required for trimming
Solution Approach 1:
The base current redistribution circuit is divided into two separate N-channel transistors (first and second N-channel transistors), each responsible for redistributing base current from one of the two current legs. This segmentation allows independent optimization of current distribution in each leg, achieving better temperature coefficient without requiring overly complex integrated structures.
Solution Approach 2:
The base current redistribution circuit acts as an intermediary between the current legs and the bipolar transistors. By introducing this intermediate current redistribution stage, the patent achieves precise control over base current distribution, which directly improves the temperature coefficient while maintaining manageable circuit complexity through modular design.
2Manufacturing precision
If multiple test passes at different temperatures are used for trimming, then the temperature coefficient can be optimized, but the manufacturing cost and complexity increase
Solution Approach 1:
The base current redistribution circuit with its two N-channel transistors automatically adjusts and redistributes base currents based on temperature variations during normal operation. This self-adjusting mechanism provides continuous temperature compensation without requiring external trimming procedures or multiple test passes, thereby reducing manufacturing complexity and cost while maintaining high temperature coefficient performance.
3Stability of the object's composition
If base current redistribution is implemented, then temperature stability improves, but circuit complexity increases
Solution Approach 1:
The patent changes the electrical parameters (base current distribution) by introducing N-channel transistors that dynamically adjust current flow based on temperature. This parameter change approach improves temperature stability while keeping the circuit structure relatively simple through the use of standard transistor components rather than complex specialized structures.
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 circuit achieves a low temperature coefficient with reduced manufacturing costs and complexity, operating in a small size with low power consumption and improved temperature stability, while maintaining a stable bandgap reference voltage.
Implementation Method 1
A bandgap reference voltage generating circuit includes a Brokaw bandgap cell circuit... a first bipolar NPN transistor QA, a second bipolar NPN transistor QB, and a ΔVBE sense resistor
Data Source
AI summary
A bandgap reference voltage generating circuit includes a bandgap cell, a tail resistor circuit, a high-order curvature compensation current generating circuit, an IZTAT current sink circuit, and a start-up circuit. The bandgap cell has a base current redistribution circuit that drives the bases of the bipolar transistors using a first base resupply current taken from the first current leg of the cell, and that uses a matched second base resupply current taken from the second current leg of the cell. VBG error due to bipolar current gain variation is reduced. The N-channel transistors of the curvature compensation current generating circuit operate in the near threshold region. The output current of the compensation circuit varies as power of approximately 2.1 of the input current. The tail resistor circuit is programmable in various ways so that the amount of curvature correction can be tailored and trimmed.