Op-Amp Level Shifter Circuit for Threshold Offset Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional operational amplifier circuits face accuracy issues due to offset in level shifted voltage caused by transistor threshold value variations, especially at low power supply voltages, leading to reduced output signal accuracy.
Innovation Solution
The operational amplifier circuit design includes first and second differential amplifier circuits, a level shifter unit, and an output circuit with complementary transistors, where the level shifted voltage is maintained constant by setting the gate-source voltages of transistors in the level shifter unit to equalize the threshold values, ensuring ideal operation regardless of process variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional level shifter unit with fixed resistors is used, then circuit structure is simple, but level shifted voltage has offset due to transistor threshold value variations
Solution Approach 1:
The patent changes the parameter of transistor gate-source voltages to equalize threshold values. By adjusting Vgs1 and Vgs2 to make |Vth1|=|Vth2|, the level shifted voltage offset is eliminated. This is achieved by controlling the gate potentials of transistors T1 and T2 in the level shifter unit, transforming the fixed resistor configuration into a dynamically controlled voltage configuration that compensates for process variations.
2Use of energy by moving object
If power supply voltage is reduced for lower power consumption, then power efficiency improves, but output signal accuracy deteriorates due to increased voltage offset
Solution Approach 1:
The patent converts the harmful effect of transistor threshold value variations (which cause offset) into a beneficial effect by actively controlling gate-source voltages to equalize thresholds. The potential harm of process variations is transformed into a controlled parameter adjustment, allowing accurate operation at low supply voltages where the offset would normally be significant.
3Adaptability or versatility
If transistor threshold values vary due to process variations, then manufacturing adaptability improves, but level shifted voltage stability deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the gate-source voltages Vgs1 and Vgs2 are controlled based on the requirement to equalize threshold values. By monitoring and adjusting these voltages to maintain |Vth1|=|Vth2|, the system compensates for process variations and maintains stable level shifted voltage output despite manufacturing tolerances.
Data Source
AI summary
A level shifter unit outputting a level shifted signal generated by level shifting of output signals of the first and second differential amplifier circuits, and an output circuit including complementary output transistors series being coupled between the high potential power supply and the low potential power supply and inputting the level shifted signal.