MOS Output Stage Current Mirror for Low-Voltage Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electronic circuit output stages with voltage division circuits face issues when powered with low supply voltages, as they become sensitive to MOS transistor threshold voltage variations, leading to insufficient current for loads and varying output voltages due to deviations in transistor characteristics.
Innovation Solution
The proposed solution involves an electronic circuit output stage with a first branch comprising a series connection of N-channel and P-channel MOS transistors diode-connected and coupled to constant current sources, and a second branch forming a current mirror, where the output terminal is connected between the second N-channel and P-channel transistors, allowing for a voltage division circuit that is less sensitive to threshold variations and capable of operating with low power supply voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low power supply voltage is used to reduce power consumption, then power consumption decreases, but the current in the first branch decreases and may not be sufficient to power the load
Solution Approach 1:
The patent changes the operating parameters of the circuit by using constant current sources instead of resistive voltage division, allowing the circuit to maintain sufficient current at lower supply voltages. The constant current sources ensure that the current remains stable regardless of the reduced voltage, resolving the contradiction between low power consumption and sufficient power delivery.
2Use of energy by moving object
If voltage Vdd is decreased to reduce power consumption, then power consumption decreases, but the output voltage varies due to threshold voltage deviations of MOS transistors
Solution Approach 1:
The patent changes the circuit architecture from resistive voltage division to constant current source operation, which stabilizes the output voltage against threshold voltage variations. By using constant current sources, the voltage at the output node becomes less sensitive to transistor threshold variations, maintaining stability even at low supply voltages.
Solution Approach 2:
The constant current sources implicitly provide feedback control to maintain stable operating conditions. The current mirrors copy the reference currents accurately, ensuring that output current remains proportional and stable despite variations in supply voltage or transistor characteristics.
3Device complexity
If conventional voltage division circuit is used, then circuit structure is simple, but the circuit becomes sensitive to MOS transistor threshold voltage variations
Solution Approach 1:
The patent changes the fundamental operating principle from resistive voltage division to constant current source operation. This parameter change transforms the circuit from being sensitive to threshold voltage variations into one that is insensitive, as constant current sources maintain stable current regardless of voltage variations across the transistors.
Data Source
AI summary
An electronic circuit including: a first branch, placed between two terminals of application of a D.C. voltage, including a series connection of a first constant current source, of a first diode-connected N-channel MOS transistor, of a first diode-connected P-channel MOS transistor, and of a second constant current source; a second branch, parallel to the first branch, comprising a series connection of a second N-channel MOS transistor connected as a current mirror on the first N-channel MOS transistor and of a second P-channel MOS transistor connected as a current mirror on the first P-channel transistor; and an input terminal connected between the first N-channel and P-channel transistors and an output terminal connected between the second N-channel and P-channel transistors.