Power Source Circuit with Bandgap Reference Voltage Detection
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Solution Overview
Problem
Conventional power source circuits that output bandgap reference voltage often produce erroneous signals when the voltage is not in the desired state, leading to incorrect operation of connected circuits, and these signals are not accurately reflective of the actual bandgap reference voltage state, especially under temperature variations.
Innovation Solution
A power source circuit configuration utilizing three bipolar transistors with different emitter areas and a current mirror circuit, along with specific resistor connections, to accurately set and output a bandgap reference voltage with a temperature coefficient of 0 V/°C, ensuring the detection signal accurately reflects the voltage state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional power source circuit outputs a bandgap reference voltage, then a detection signal is generated to indicate voltage output, but the detection signal becomes erroneous when the bandgap reference voltage is not in the desired state
Solution Approach 1:
The patent modifies the detection mechanism by changing the parameter being monitored from direct voltage level detection to current magnitude detection. The detection circuit measures the current flowing through the bandgap reference voltage output, which provides a more reliable indication of proper voltage generation that is less susceptible to temperature variations and circuit state anomalies.
Solution Approach 2:
The patent introduces an intermediary current measurement mechanism between the bandgap reference voltage output and the detection signal generation. Instead of directly detecting voltage presence, the system uses current flow as an intermediate indicator that more accurately reflects the actual operational state of the voltage reference circuit.
2Measurement precision
If the detection signal is generated based on conventional voltage detection, then the circuit structure is simple, but the signal does not accurately reflect the actual bandgap reference voltage state
Solution Approach 1:
The patent replaces direct voltage detection (electrical field measurement) with current detection (charge flow measurement). This substitution provides more accurate measurement of the actual operational state while maintaining a relatively simple circuit implementation through current-sensing transistors and comparison circuits.
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 solution provides a stable and accurate output of bandgap reference voltage and detection signal that is insensitive to temperature changes, ensuring correct operation of connected circuits by setting the bandgap output voltage and detection threshold voltage with zero temperature coefficients.
Implementation Method 1
a power source circuit that outputs a bandgap reference voltage
Implementation Method 2
a bandgap reference voltage with a temperature coefficient of 0 V/°C
Data Source
AI summary
According to an embodiment, a power source circuit has first, second, and third one-conductivity-type transistors with commonly connected emitters, wherein the first transistor has an emitter area that is N times those of the second and third transistors. The power source circuit outputs a reference voltage that is set by a voltage drop that is caused at a resistance between bases of the first and second transistors and a forward voltage of a PN-junction diode, and outputs a BG_OK signal in response to a potential at a collector of the third transistor.