Closed-Loop Voltage Reference Circuit for Low-Voltage Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional current-mode voltage reference circuits are highly sensitive to power supply noise, device noise, and leakage currents, making it difficult to achieve high precision and performance, especially when operating below the native bandgap reference voltage.
Innovation Solution
A closed-loop circuit topology is employed that combines a PTAT signal with a CTAT signal generated based on the silicon bandgap, using a feedback loop to adjust the operation and maintain the reference voltage, reducing temperature dependence and compensating for changes in output load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional current-mode voltage reference circuits are used, then the circuit can operate below the native bandgap reference voltage, but the circuit becomes highly sensitive to power supply noise, device noise, and leakage currents
Solution Approach 1:
The patent implements a closed-loop feedback circuit that continuously monitors the reference voltage output and adjusts the bias currents to maintain stability. The feedback mechanism compensates for variations in power supply voltage, temperature, and process parameters by dynamically regulating the operating point of the bandgap reference circuit, thereby reducing sensitivity to noise and leakage currents while maintaining operation below the native bandgap voltage.
Solution Approach 2:
The patent employs parameter changes by dynamically adjusting bias currents and voltage levels within the reference circuit based on operating conditions. The circuit modifies key parameters such as collector currents of bipolar transistors and voltage drops across resistive elements to optimize the reference voltage stability across different operating points, enabling low-voltage operation while maintaining precision.
2Use of energy by moving object
If the reference circuit operates below the native bandgap reference voltage, then power consumption is reduced, but power supply rejection ratio deteriorates
Solution Approach 1:
The closed-loop feedback circuit enhances power supply rejection by continuously monitoring the reference voltage and adjusting bias currents to compensate for power supply variations. This feedback mechanism maintains stable operation even at reduced voltage levels where power supply noise would normally have a greater impact, thereby improving power supply rejection ratio while maintaining low power consumption.
Solution Approach 2:
The circuit employs dynamic biasing where the operating point is continuously adjusted based on power supply voltage levels and load conditions. This dynamic adaptation allows the circuit to maintain optimal performance across a wide voltage range, improving power supply rejection at low operating voltages while keeping power consumption minimized.
3Stability of the object's composition
If temperature compensation is implemented by combining PTAT and CTAT currents, then temperature stability is improved, but circuit complexity increases
Solution Approach 1:
The patent combines PTAT (proportional-to-absolute-temperature) and CTAT (complementary-to-absolute-temperature) current paths within a unified bandgap reference circuit architecture. By merging these two temperature-dependent current sources and summing their effects at a common node, the circuit achieves temperature compensation where the opposing temperature coefficients cancel each other out, producing a stable reference voltage with minimal temperature drift.
Solution Approach 2:
The circuit achieves temperature stability by carefully selecting and adjusting parameters such as transistor area ratios, current scaling factors, and resistive divider ratios to balance the PTAT and CTAT components. This parameter optimization allows temperature compensation with minimal additional circuitry, maintaining simplicity while achieving high temperature stability.
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
This approach allows for stable operation below the native bandgap reference voltage, improving power supply rejection ratio and maintaining reference voltage stability despite variations in operational parameters.
Implementation Method 1
A commonly used property of silicon used in many reference circuits is the band or energy gap of silicon. The band gap refers to an energy range in silicon where no electronic states can exist. Using the band gap allows the generation of currents and voltages that vary little with variations in process and power supply voltage.
Implementation Method 2
A commonly used property of silicon used in many reference circuits is the band or energy gap of silicon. The band gap refers to an energy range in silicon where no electronic states can exist. Using the band gap allows the generation of currents and voltages that vary little with variations in process and power supply voltage.
Data Source
AI summary
A voltage reference circuit included in a computer system includes two bipolar devices with two different current densities which are used to generate two base-emitter voltages, which are scaled using divider circuits. The voltage reference circuit also includes a feedback circuit that generates a reference voltage using the scaled base-emitter voltages and a feedback signal. The feedback signal is generated using the reference signal and combined with one of the scaled base-emitter voltages to compensate for variations in load current from the reference circuit.