Differential Current Source Using One Resistor for PTAT, NTAT, and ZTC Bias
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Solution Overview
Problem
Integrated circuits face challenges in accurately generating currents due to process drift and batch-to-batch differences, which affect the yield and require multiple current sources with different temperature coefficients, necessitating a method to generate process-independent and batch-independent current sources.
Innovation Solution
A differential voltage controlled current source is used to generate multiple currents based on a single external resistor, allowing for the creation of zero temperature coefficient (ZTC), proportional to absolute temperature (PTAT), and inversely proportional to absolute temperature (NTAT) currents, which are independent of process and batch variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple current sources with different temperature coefficients are generated using traditional methods, then the integrated circuit can compensate for temperature drift and meet power consumption requirements, but process drift and batch-to-batch differences reduce the accuracy of internally generated currents and reduce manufacturing yield
Solution Approach 1:
The patent introduces an external reference resistor as an intermediary element that is coupled to the integrated circuit. This external resistor serves as a stable reference that is not affected by internal process variations. The circuit uses this external reference to generate multiple current sources (ZTC, PTAT, NTAT) with high accuracy, thereby resolving the contradiction between current source accuracy and manufacturing yield by shifting the reference standard from internal to external.
2Device complexity
If a single external resistor is used to generate multiple current sources, then the device complexity is reduced and manufacturing yield is improved, but the circuit must accurately generate multiple currents with different temperature coefficients from a single reference
Solution Approach 1:
The patent implements a universal current generation circuit that can produce multiple types of current sources (ZTC, PTAT, NTAT) from a single external reference resistor. The circuit includes switching mechanisms and configuration options that allow it to adaptively generate different current types based on control signals, thereby achieving multi-functionality and resolving the contradiction between device simplicity and current source versatility.
Data Source
AI summary
A differential voltage controlled current source generating one or more output currents is based upon a single external resistor. The differential voltage controlled current source may generate an output current that is proportional to a received differential voltage and a bias current with the use of a single external resistor. The technique may be used to generate multiple accurate and process independent current sources. The current sources may be a zero temperature coefficient (ZTC) current, a proportional to absolute temperature (PTAT) current, or an inversely proportional to absolute temperature (NTAT) current. The output of the current sources may be inversely proportional to the resistance of the external resistor.