Current Mirror Reference Circuit for PVT-Compensated Biasing
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Solution Overview
Problem
Conventional current mirror circuits fail to provide a precise reference voltage or current that compensates for process and temperature variations in transistors, leading to undesired effects in downstream components like oscillators.
Innovation Solution
A current mirroring circuit design that includes symmetric NMOS and PMOS pairs with diode-connected transistors and degeneration resistors, providing a stable reference voltage that compensates for process and temperature variations by adjusting the gate-source voltages of transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an amplifier is added to create an ideal current mirror, then supply voltage insensitivity is improved, but power consumption and die area increase
Solution Approach 1:
The patent removes the amplifier component from the conventional current mirror circuit, extracting only the essential current mirroring function while eliminating the power-consuming amplification stage. This achieves supply voltage insensitivity through the intrinsic properties of the diode-connected transistors and current mirror architecture without requiring additional active components.
Solution Approach 2:
The patent replaces the expensive and power-consuming amplifier with a simpler, lower-cost current mirror structure using basic transistor and resistor components. This substitution achieves the desired functionality with reduced power consumption and lower component cost, accepting that the simpler structure has its own characteristics that are sufficient for the application.
2Reliability
If an amplifier is added to create an ideal current mirror, then supply voltage insensitivity is improved, but die area increases
Solution Approach 1:
The amplifier is extracted and removed from the circuit, leaving only the essential current mirror components. This reduction in component count directly decreases the die area while maintaining the core functionality of providing a stable reference current that is insensitive to supply voltage variations.
Solution Approach 2:
The patent merges the reference current generation and current mirroring functions into a single integrated structure. By combining these functions without requiring a separate amplifier stage, the design achieves supply voltage insensitivity in a compact footprint that minimizes die area.
3Device complexity
If conventional current mirror circuits are used, then circuit simplicity is maintained, but compensation for process and temperature variation is insufficient
Solution Approach 1:
The patent introduces local quality by using diode-connected transistors in the current mirror structure, which provide temperature and process variation compensation at the local level where the reference current is generated. This localized approach maintains overall circuit simplicity while adding the necessary compensation characteristics in the critical reference generation region.
Solution Approach 2:
The patent utilizes the temperature-dependent parameters of diode-connected transistors to automatically compensate for process and temperature variations. By changing the operating parameters of the reference current generation circuit through the diode connection, the system achieves PVT compensation without adding complex control circuitry, maintaining simplicity while improving reliability.
Data Source
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AI summary
A current mirroring circuit including: a first portion having a first resistor and a first transistor, the first transistor having a control terminal coupled to a control terminal of a first diode-connected transistor; and a second portion having a second resistor and a second transistor, the second transistor having a control terminal coupled to a control terminal of a second diode-connected transistor, the first portion being in electrical communication with a first power level and the second portion being in electrical communication with a second power level, the first portion being coupled to the second portion.