Band Gap Voltage Reference Circuit for Sub-1V Supply Operation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing Band Gap voltage generators struggle with maintaining operational amplifier input terminal voltage above 1V, especially at low temperatures, leading to mirroring errors and poor performance at low supply voltages.
Innovation Solution
A temperature-compensated voltage reference generator circuit dynamically adjusts the control terminals of bipolar transistors connected to the operational amplifier, maintaining a constant voltage across the operational amplifier by generating a base biasing voltage that inversely compensates the base-emitter voltage variations, ensuring correct operation of the n-channel pair even at supply voltages below 1V.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the operational amplifier input terminal voltage is maintained above 1V to ensure correct operation, then the reliability is improved, but the adaptability to low supply voltage applications deteriorates
Solution Approach 1:
The patent inverts the conventional approach by making the bipolar transistor emitters the reference potential (0V) rather than the bases. This inversion allows the operational amplifier inputs to operate at lower voltages while maintaining correct operation, enabling the circuit to function with supply voltages below 1V
Solution Approach 2:
The patent changes the voltage parameter relationships in the circuit by using temperature-compensated voltage references and adjusting the biasing scheme. This allows the operational amplifier to operate reliably at lower input voltages while maintaining temperature compensation functionality
2Stability of the object's composition
If the base-emitter voltage variations are compensated to maintain stable operation, then the temperature stability is improved, but the device complexity increases
Solution Approach 1:
The patent implements self-service by using the circuit's own temperature-dependent characteristics to generate compensation. The bipolar transistors' base-emitter voltage variations are automatically compensated through the temperature-compensated voltage reference, eliminating the need for external temperature sensing or complex control circuits
Solution Approach 2:
The patent merges the voltage reference generation and temperature compensation functions into a single integrated circuit block. The operational amplifier, bipolar transistors, and voltage references work together in a unified configuration that simultaneously provides both functions without requiring separate 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 ensures stable operation of the Band Gap voltage reference across a wide temperature range with low supply voltages, reducing systematic errors and maintaining high noise rejection and temperature stability.
Implementation Method 1
a voltage VBG almost independent from the working temperature can be obtained in a simple way by means of a bipolar transistor by implementing the following equation: VBG = VBE + nVT
Implementation Method 2
an operational amplifier, having in turn a first and a second input terminal connected to an input stage essentially comprising a generator circuit of a current proportional to the temperature
Implementation Method 3
a current mirror connected to the first supply voltage reference and inserted between the first and the second input terminal of the operational amplifier
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A circuit (10) is described for the generation of a temperature-compensated voltage reference (VBG) of the type comprising at least one generator circuit of a Band Gap voltage (13), inserted between a first and a second voltage reference (VDD, GND) and including an operational amplifier (OA1), having in turn a first and a second input terminal (T1, T2) connected to an input stage (15) connected to these first and second input terminal (T1, T2) and comprising at least one pair of a first and a second bipolar transistor (Q1, Q2) for the generation of a first voltage component (ΔVBE) proportional to the temperature. Advantageously according to the invention, the circuit (10) comprises the control block (14) connected to the generator circuit of a Band Gap voltage (13) in correspondence with at least one first control node (Xc1) which is supplied with a biasing voltage value (VBase) comprising at least one voltage component which increases with the temperature for compensating the variations of the base-emitter voltage (Vbe) of the first and second bipolar transistors (Q1, Q2) and ensure the turn-on of a pair of input transistors of the operational amplifier (OA1). The circuit (10) has an output terminal (OUT) suitable for supplying a temperature-compensated voltage value (VBG) obtained by the sum of the first voltage component proportional to the temperature (ΔVBE) and of a second component inversely proportional to the temperature (VBE3).