System and method for voltage generation
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Solution Overview
Problem
Existing reference voltage generator circuits face challenges in achieving high accuracy at low power supply voltages due to offset errors and temperature non-linearity, particularly when operating below the bandgap voltage of silicon.
Innovation Solution
A voltage generator circuitry is designed with first, second, and third bipolar transistors having commonly-connected base electrodes, current mirror circuitries, differential amplifiers, and a current-voltage conversion circuitry, which cancels temperature dependence by adjusting collector currents and base currents to produce a highly accurate output voltage, excluding the influence of error amplifier offset voltages and non-linear temperature terms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a bandgap voltage reference is used to achieve high accuracy, then measurement precision is improved, but the power supply voltage requirement increases (cannot operate below bandgap voltage)
Solution Approach 1:
The patent changes the operating parameters by using bipolar transistors with different emitter areas to generate PTAT and CTAT voltage components that can be combined to achieve temperature compensation. This allows the circuit to operate at supply voltages below the traditional bandgap voltage while maintaining high accuracy through parameter optimization of the transistor areas and resistor values.
Solution Approach 2:
The patent creates a composite voltage reference by combining multiple voltage components (PTAT and CTAT) generated from bipolar transistors with different emitter areas. This composite approach allows the circuit to achieve temperature-independent reference voltage operation at lower supply voltages than traditional bandgap references.
2Stability of the object's composition
If bipolar transistors are used in reference voltage generation, then temperature compensation capability is improved, but non-linearity of temperature property increases
Solution Approach 1:
The patent segments the temperature compensation function into multiple bipolar transistors with different emitter areas (e.g., Q1, Q2, Q3 with areas A, 2A, 3A). Each transistor contributes a specific temperature-dependent voltage component, and their combined output achieves linear temperature compensation. This segmentation allows precise control over the temperature characteristics.
Solution Approach 2:
The patent applies local quality by giving each bipolar transistor a specific emitter area ratio (1:2:3) to generate different weighted temperature-dependent voltage components. This localized differentiation in transistor geometry allows the circuit to achieve overall linear temperature compensation while each individual transistor maintains its characteristic non-linear behavior.
3Ease of operation
If error amplifier offset voltage is present in the circuit, then circuit functionality is maintained, but reference voltage accuracy deteriorates
Solution Approach 1:
The patent extracts and eliminates the error amplifier component from the reference voltage generation path. Instead of using an error amplifier to control the reference voltage, the circuit directly uses the inherent temperature-dependent characteristics of bipolar transistors with different emitter areas to generate the compensated reference voltage, thereby removing the source of offset voltage errors.
Solution Approach 2:
The patent implements self-service by allowing the bipolar transistors to automatically generate and compensate for temperature effects without external error amplification. The circuit uses the natural temperature-dependent behavior of the transistors to self-regulate and produce an accurate reference voltage without requiring additional active compensation components.
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 circuitry achieves high accuracy and reduces temperature dependence, allowing operation on power supply voltages lower than the bandgap voltage of silicon while suppressing accuracy deterioration from non-linear temperature properties, thereby enhancing the precision of the output voltage.
Implementation Method 1
The current-voltage conversion circuitry converts the sum current of the first and second currents into an output voltage
Implementation Method 2
A component for which the temperature dependency is canceled is commonly abbreviated to ZTAT, and the PTAT, CTAT and ZTAT current components may be referred to as IPTAT, ICTAT and IZTAT, respectively
Data Source
AI summary
A voltage generator circuitry includes first to third bipolar transistors having commonly-connected base electrodes, first and second current mirror circuitries, first and second differential amplifiers; a first resistor; and a current-voltage conversion circuitry. The first current mirror circuitry supplies currents to the first to third bipolar transistors and to the current-voltage conversion circuitry. The second current mirror circuitry supplies currents to the first to third bipolar transistors, and s to the current-voltage conversion circuitry. The first and second differential amplifiers control the first and second current mirror. The current-voltage conversion circuitry converts a sum current of the first and second currents into an output voltage.