Push-Pull Output Driver With Current Mirror PVT Stability
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Solution Overview
Problem
Conventional push-pull voltage drivers in operational amplifiers are susceptible to variations in performance due to Process, Supply Voltage, and Temperature (PVT) conditions, leading to inconsistent steady-state current consumption.
Innovation Solution
A voltage driver circuit with a level shifter and a push-pull output stage using transistors in a current mirror configuration, where one transistor is configured as a source follower and the other as a common source amplifier, with a bias current generator to maintain well-controlled steady-state DC output, implemented using either field effect transistors or bipolar transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional push-pull output drivers are used, then quick adjustment of output voltages is provided, but performance varies due to PVT conditions
Solution Approach 1:
The patent changes the configuration parameters of the output driver by using a current mirror arrangement where the second transistor mirrors the current of the first transistor. This parameter change makes the output driver's performance less sensitive to PVT variations, as the current mirror inherently compensates for process and temperature effects, while maintaining the fast response capability needed for quick output voltage adjustment.
2Power
If conventional push-pull output drivers are used, then output driving capability is provided, but steady state current consumption varies
Solution Approach 1:
The current mirror configuration acts as a feedback mechanism where the second transistor monitors and mirrors the current through the first transistor. This feedback loop ensures that the steady-state current consumption is well-controlled and consistent across different PVT conditions, while still providing sufficient output driving capability when needed.
Data Source
AI summary
A voltage driver circuit for an output stage of an operational amplifier, or other circuits, includes a level shifter and an output driver including a source follower and a common source amplifier in a push-pull configuration. The level shifter generates a node voltage as a function of an input voltage on the input node. The output driver including a first transistor having a control terminal receiving the node voltage, and connected between a supply voltage and an output node, and a second transistor having a control terminal receiving the input voltage from the input node, and connected between the output node and a reference voltage, wherein the first and second transistors have a common conductivity type.