Low Voltage Current Mode Bandgap Circuit Resistor Segmentation
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Solution Overview
Problem
Conventional bandgap reference circuits require large resistors to generate accurate reference voltages at low supply voltages, leading to increased area occupation and costs, and suffer from inaccuracies and susceptibility to manufacturing variations.
Innovation Solution
A proportional to absolute temperature (PTAT) generator that produces PTAT current and VBE in a first regulation loop, combined with a voltage-to-current converter to generate a complementary to absolute temperature current, resulting in a zero temperature coefficient current using a single resistor, which can be split into smaller resistors to maintain area efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If large resistors are used to generate accurate reference voltages at low supply voltages, then measurement precision is improved, but area occupation increases
Solution Approach 1:
The patent divides a single large resistor into multiple smaller resistors connected in parallel. This segmentation maintains the equivalent resistance value needed for accurate reference voltage generation while significantly reducing the total area occupied. For example, instead of using one large resistor, the circuit uses several smaller resistors in parallel, each occupying less area, but collectively providing the same electrical function with reduced footprint.
2Measurement precision
If conventional bandgap reference circuits are used, then reference voltage accuracy is maintained, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into a unified current mode bandgap reference circuit that operates from low supply voltages. By integrating the PTAT current generator, VBE generator, and voltage-to-current converter into a single coordinated system, the design achieves accurate reference voltage generation without requiring separate complex circuits for each function, thereby reducing overall device complexity while maintaining precision.
3Use of energy by moving object
If low supply voltages are used, then power consumption is reduced, but reference voltage accuracy deteriorates
Solution Approach 1:
The patent changes the operating parameters of the bandgap reference circuit to enable low voltage operation. Specifically, it uses current mode operation instead of voltage mode, which allows the circuit to function accurately at supply voltages as low as 1.2V. The circuit employs PTAT current generation and VBE voltage generation with careful matching of transistor and resistor parameters to maintain accuracy despite the reduced supply voltage, thereby achieving both low power consumption and high precision.
Data Source
AI summary
A proportional to absolute temperature (PTAT) generator, for example, generates a PTAT current (IPTAT) and a VBE (voltage base-to-emitter) in a first regulation loop. A voltage-to-current converter is operable to generate a complementary to absolute temperature current (ICTAT). The IPTAT and ICTAT are summed to obtain a zero temperature coefficient current (IZTC). One ICTAT and one resistor are used to generate the IZTC signal.