Bandgap Reference Voltage Circuit With Fewer Doping Steps
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Solution Overview
Problem
Conventional reference voltage generator circuits require additional doping steps, increasing manufacturing costs and needing higher power supply voltages due to elevated first conduction threshold voltages.
Innovation Solution
A reference voltage generator circuit design utilizing two transistors with different conduction threshold voltages, coupled with a clamping device and feedback circuit, to generate a bandgap reference voltage with temperature compensation, reducing manufacturing steps and power supply requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If P-type impurities are doped into the conductive layer to increase the first conduction threshold voltage, then the bandgap reference voltage can be generated according to the threshold voltage difference, but the number of manufacturing steps increases and manufacturing cost increases
Solution Approach 1:
The invention extracts and eliminates the P-type doping step from the manufacturing process. Instead of doping the first conductive layer with P-type impurities to increase its threshold voltage, the patent uses a combination of an undoped first conductive layer and a specially designed second conductive layer with N-type doping, achieving the required threshold voltage difference through structural design rather than additional doping steps.
Solution Approach 2:
The invention changes the approach from modifying the first conductive layer's threshold voltage through P-type doping to achieving the threshold voltage difference by combining an undoped first layer with an N-type doped second layer. This parameter change in the doping strategy eliminates the need for P-type doping while maintaining the functional requirement.
2Reliability
If P-type impurities are doped to increase the first conduction threshold voltage, then the threshold voltage difference can be achieved, but the required power supply voltage increases
Solution Approach 1:
The invention changes the threshold voltage achievement strategy from increasing the first threshold voltage (which requires higher power supply) to maintaining a low first threshold voltage with undoped material and achieving the difference through the second layer's N-type doping. This parameter change in the doping configuration allows operation at lower power supply voltages.
3Reliability
If P-type doping is performed on the first conductive layer, then the first conduction threshold voltage increases, but the manufacturing cost increases due to additional doping steps
Solution Approach 1:
The invention extracts and removes the P-type doping step from the manufacturing process entirely. The required threshold voltage characteristics are achieved through a combination of undoped and N-type doped layers, eliminating the need for costly P-type doping operations and reducing manufacturing complexity.
Data Source
AI summary
A reference voltage generator circuit includes: a first transistor and a second transistor, wherein the first transistor and the second transistor are coupled with each other and are located on a substrate, wherein the first transistor has a first conduction threshold voltage and a first rated voltage, wherein the second transistor has a second conduction threshold voltage and a second rated voltage, wherein the first rated voltage is higher than the second rated voltage; wherein the reference voltage generator circuit is configured to generate a bandgap reference voltage with temperature compensation according to a difference between the first conduction threshold voltage and the second conduction threshold voltage.