Dual-Mode PTAT Current Circuit Using Switched Transistors
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Solution Overview
Problem
Traditional bandgap voltage reference circuits are complex and not cost-efficient, and they fail to provide stable temperature-independent currents for higher-order device characteristics across a range of temperatures, leading to variations in generated voltages and currents.
Innovation Solution
A dual-mode proportional to absolute temperature (PTAT) current circuit is designed, incorporating a voltage stabilizing circuit with MOS transistors and semiconductor devices with temperature-dependent coefficients, along with switch-controlled load currents to maintain current magnitudes at different temperatures, using a combination of temperature sensors to manage the flow of load currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional bandgap voltage reference circuits are used to generate temperature-compensated currents, then voltage stability over temperature is improved, but device complexity increases and cost efficiency deteriorates
Solution Approach 1:
The circuit is segmented into distinct functional blocks: a voltage reference circuit generating Vref, a first current mirror circuit (M1-M4) generating first PTAT current, a second current mirror circuit (M5-M8) generating second PTAT current, and temperature sensing/control circuitry. Each block performs a specific function, allowing independent optimization and simplifying overall design while maintaining temperature compensation capability.
Solution Approach 2:
The voltage reference circuit Vref serves multiple functions: it provides a stable reference voltage for current generation, enables temperature compensation through its inherent PTAT characteristics, and controls both current mirror circuits. This multi-functionality reduces the need for separate dedicated circuits, thereby simplifying the overall design.
2Reliability
If temperature-independent currents are generated across a wide temperature range, then operational reliability is improved, but the circuit requires complex temperature compensation mechanisms increasing device complexity
Solution Approach 1:
The circuit exploits changes in transistor parameters with temperature to generate PTAT currents. Specifically, the base-emitter voltage Vbe of bipolar transistors has a known temperature dependence, and this parameter change is harnessed to create currents that vary predictably with temperature, enabling temperature compensation without complex external circuits.
Solution Approach 2:
Temperature sensing elements monitor the actual temperature of the circuit and provide feedback to the current control mechanisms. This feedback enables dynamic adjustment of the PTAT currents to maintain temperature-independent operation, improving reliability while using relatively simple feedback paths rather than complex open-loop compensation networks.
3Adaptability or versatility
If dual-mode or multi-mode current magnitudes are generated at different temperatures, then adaptability is improved, but the circuit requires switch-controlled mechanisms increasing device complexity
Solution Approach 1:
The circuit transitions from static to dynamic operation by introducing temperature-dependent switching. Switches S1 and S2 dynamically connect or disconnect current mirror circuits based on temperature thresholds, allowing the circuit to adapt its current generation mode. This dynamic behavior enables dual-mode operation (low-temperature mode and high-temperature mode) while using relatively simple switch-based control rather than complex programmable logic.
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 circuit generates stable voltage references and temperature-dependent currents with significant magnitudes, enhancing the flexibility and cost-effectiveness by maintaining temperature independence and enabling dual-mode or multi-mode applications.
Implementation Method 1
voltage stabilizing circuit with MOS transistors and semiconductor devices with temperature-dependent coefficients
Implementation Method 2
circuit for generating a dual-mode PTAT current based on a voltage reference
Data Source
AI summary
The present invention discloses a circuit for generating a dual-mode proportional to absolute temperature (PTAT) current. The circuit includes a voltage stabilizing circuit to provide a voltage reference, and a load current control circuit comprising a first transistor to provide a first load current based on the voltage reference, a second transistor to provide a second load current based on the voltage reference, a first switch to control whether to allow the first load current to flow therethrough in response to different predetermined temperatures, and a second switch to control whether to allow the second load current to flow therethrough in response to the different predetermined temperatures. A resultant current resulting from at least one of the first load current or the second load current has different current magnitudes at the different predetermined temperatures.