Bias Voltage Feedback Circuit for Stable Constant Current
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Solution Overview
Problem
Semiconductor apparatuses face challenges in maintaining a constant bias voltage level due to variations in processes, voltages, and temperatures, which affects the generation of a predetermined constant current.
Innovation Solution
A voltage generator comprising a bias voltage generation circuit and a compensation circuit that adjust the voltage levels of first and second bias voltages based on each other, using a band-gap reference voltage generation circuit to maintain predetermined voltage levels despite process and temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bias voltage generation circuit is used to generate constant current, then current generation function is achieved, but voltage level stability deteriorates due to process, voltage, and temperature variations
Solution Approach 1:
The patent implements a feedback mechanism where the second bias voltage (generated from the first bias voltage) is fed back to adjust the first bias voltage level. The compensation circuit monitors the second bias voltage and automatically adjusts the first bias voltage to compensate for PVT variations, ensuring stable current generation without requiring external intervention.
Solution Approach 2:
The patent changes the voltage level parameter of the first bias voltage dynamically based on the second bias voltage. By adjusting the voltage level of the first bias voltage according to process, voltage, and temperature conditions (through the relationship with the second bias voltage), the circuit maintains constant current generation despite PVT variations.
2Adaptability or versatility
If transistor threshold voltage varies due to PVT changes, then circuit adaptability to different conditions is improved, but manufacturing precision of constant current deteriorates
Solution Approach 1:
The feedback mechanism uses the second bias voltage (which reflects PVT conditions affecting transistor threshold voltage) to automatically adjust the first bias voltage. This closed-loop control ensures that even when transistor characteristics vary due to PVT changes, the constant current precision is maintained through automatic compensation.
Solution Approach 2:
The patent dynamically changes the voltage level parameter of the first bias voltage based on PVT conditions. By linking the first bias voltage adjustment to the second bias voltage (which varies with PVT), the circuit adapts to different operating conditions while maintaining precise constant current generation.
Data Source
AI summary
A voltage generator includes a bias voltage generation circuit and a compensation circuit. The bias voltage generation circuit generates a first bias voltage based on a reference current and generates a second bias voltage based on the first bias voltage. The compensation circuit changes a voltage level of the first bias voltage based on the second bias voltage.