Reference Current Generator Temperature Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Prior art reference current generator circuits in RFID systems exhibit significant temperature-dependent variations, leading to increased power consumption and degraded performance due to reference currents that increase by more than 45% over a wide temperature range of −40° C. to +65° C.
Innovation Solution
A reference current generator circuit design that includes a core circuit with a parallel configuration of transistors, where a third transistor with a different threshold voltage counteracts the positive temperature coefficient of the first and second transistors, maintaining a substantially constant voltage differential across a resistive component, thus reducing temperature-dependent variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If prior art reference current generator circuits are used, then reference current is generated, but reference current increases by more than 45% over temperature range causing increased power consumption
Solution Approach 1:
The patent changes the temperature dependence parameter of the reference current by using a parallel transistor configuration where transistors with different threshold voltages are combined. The first transistor has a higher threshold voltage and the second transistor has a lower threshold voltage, creating opposing temperature coefficients that cancel each other out. This parameter change transforms the reference current from PTAT (positive temperature coefficient) to temperature-independent, resolving the contradiction between power consumption and temperature stability.
Solution Approach 2:
The patent applies the counterweight principle by introducing a second transistor with opposite temperature characteristics to counterbalance the temperature drift of the first transistor. The third transistor with yet another threshold voltage further refines this counterbalancing act. The combined effect of these transistors with different threshold voltages creates a reference current that is insensitive to temperature changes, effectively canceling out the harmful temperature-dependent variations.
2Reliability
If prior art reference current generator circuits are used, then reference current is generated, but performance degrades due to temperature-dependent variations
Solution Approach 1:
The patent modifies the temperature response parameter of the reference current by combining multiple transistors with different threshold voltages in a parallel configuration. This parameter transformation changes the current's temperature dependence from positive (PTAT) to near-zero, enabling consistent performance across the temperature range of -40°C to +65°C without degradation.
Solution Approach 2:
The patent creates a composite transistor structure where multiple transistors with different electrical characteristics (different threshold voltages) are combined in parallel. This composite configuration integrates the beneficial properties of each individual transistor to achieve temperature insensitivity, similar to how composite materials combine different materials to achieve desired physical properties.
3Reliability
If transistors with different threshold voltages are used in parallel configuration, then temperature-independent reference current is achieved, but device complexity increases
Solution Approach 1:
The patent achieves temperature independence by changing the electrical parameters of the transistor network. By selecting transistors with specific threshold voltage ratios and configuring them in parallel with appropriate sizing, the circuit produces a temperature-independent reference current. This parameter-based approach maintains relatively simple circuit topology while achieving the desired temperature compensation.
Data Source
AI summary
Embodiments of the invention describe a core circuit for a reference current generator circuit that biases a first transistor to source a first current and a second transistor parallel to the first transistor, biased to source a second current controlled by the first current. A third transistor is coupled parallel to the second transistor and sources a third current controlled by the first current. The third transistor has a different threshold voltage than a threshold voltage of the second transistor. A resistive component coupled to conduct the second current has a resistive voltage that is substantially equal to a voltage differential between the first transistor and the second transistor. The conducting current through the resistive component is substantially independent of temperature variations.