Band Gap Reference Voltage Circuit Startup Stability
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Solution Overview
Problem
Existing semiconductor chip circuits face challenges in rapidly achieving a steady state to supply DC biases when power is applied, leading to potential operational failures and instability in analog circuits.
Innovation Solution
A circuit comprising a band gap reference voltage generator, a mirroring circuit, and a start-up circuit is used to ensure the bias generating circuit enters a steady state promptly by providing a driving current until the desired bias voltage is generated, then separating to avoid influencing the circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power is initially applied to the bias generating circuit, then the circuit should generate DC bias voltage, but the circuit may not be promptly ready to supply bias or operation may fail
Solution Approach 1:
The start-up circuit performs preliminary action by providing an initial driving current to the band gap circuit before the main operation begins. This preliminary current ensures that the band gap circuit reaches its steady state quickly and reliably, preventing operational failures during power-up. Once the reference voltage is established, the start-up circuit is turned off, having fulfilled its preliminary function.
2Speed
If the start-up circuit continuously provides driving current, then the band gap circuit reaches steady state quickly, but the start-up circuit may exert unwanted influence on the circuit after steady state is achieved
Solution Approach 1:
The start-up circuit is designed to be dynamic rather than static. It automatically adjusts its operation based on the circuit's state: providing driving current when the band gap circuit needs it to reach steady state, and automatically turning off once the steady state is achieved. This dynamic behavior ensures quick startup without causing unwanted continuous influence on the stable operating circuit.
Solution Approach 2:
The circuit employs feedback mechanisms where the mirroring circuit monitors the driving current and provides feedback signals to control the start-up circuit's operation. When the band gap circuit reaches steady state, the feedback signals cause the start-up circuit to turn off, preventing it from exerting unwanted influence on the stable circuit while maintaining quick startup performance.
3Use of energy by moving object
If the band gap circuit operates without sufficient driving current, then power consumption is reduced, but the reference voltage generation fails or becomes unstable
Solution Approach 1:
The start-up circuit provides periodic or temporary driving current only during the initial startup phase when the band gap circuit needs it to establish stable operation. Once the reference voltage is generated and the circuit reaches steady state, the start-up circuit stops providing current. This periodic action ensures reference voltage stability during critical startup while minimizing unnecessary power consumption during normal operation.
Data Source
AI summary
Provided is a circuit for generating a reference voltage. The circuit includes a band gap circuit generating a first current having a size that increases in proportion to an absolute temperature and a second current having a size that decreases in proportion to the absolute temperature, and outputting a reference voltage based on the first current and the second current; a mirroring circuit mirroring a sum of the first current and the second current and outputting a mirroring voltage that is in proportion to the sum of the first current and the second current; and a start-up circuit receiving the mirroring voltage from the mirroring circuit and providing a driving current for generating the first current or the second current to the band gap circuit until a time when the first current starts to be generated in the band gap circuit.