Push-Pull LDO Regulation With Bi-Directional Driver Feedback
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Solution Overview
Problem
Existing low-dropout (LDO) voltage regulators struggle to maintain a stable and well-specified output voltage when the input voltage falls close to the output voltage, and they lack bi-directional operation and configurable step size for current sourcing and sinking.
Innovation Solution
A push-pull LDO voltage regulator with bi-directional drivers and a feedback mechanism using multiple reference voltages and comparators to adjust the output voltage within a specified range, employing driver current limiters for temperature compensation and dynamic current sourcing/sinking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LDO regulator topology is used, then circuit simplicity is maintained, but the regulator cannot maintain stable output voltage when input voltage falls close to output voltage
Solution Approach 1:
The patent implements a push-pull output stage with bi-directional drivers that dynamically switch between sourcing and sinking current modes. The output driver transitions from a static conventional topology to a dynamic system that can actively pull the output voltage both up and down, enabling stable regulation even when input voltage approaches output voltage levels. This dynamic operation allows the regulator to maintain output stability in near-dropout conditions where conventional static topologies fail.
2Adaptability or versatility
If conventional unidirectional current operation is used, then device simplicity is maintained, but bi-directional current sourcing and sinking capability is lost
Solution Approach 1:
The patent creates a universal output driver capable of both sourcing current (pulling output voltage up) and sinking current (pulling output voltage down). The push-pull output stage incorporates complementary transistors that enable the same driver circuit to perform dual functions: acting as a current source when the output needs to be raised and as a current sink when the output needs to be lowered. This multi-functional design provides bi-directional operation capability while managing circuit complexity through integrated control.
3Ease of operation
If fixed current adjustment is used, then control simplicity is maintained, but configurable step size for voltage adjustment is lost
Solution Approach 1:
The patent implements dynamic current adjustment capability where the output driver's current magnitude can be varied in real-time based on control signals. The bi-directional drivers respond to control inputs that modulate the current strength, enabling configurable step sizes for voltage adjustment. This dynamic control mechanism allows the regulator to make fine-grained or coarse adjustments as needed, providing operational flexibility that fixed current systems cannot achieve.
4Speed
If rapid voltage adjustment is implemented, then response speed is improved, but stability control complexity increases
Solution Approach 1:
The patent employs a feedback control mechanism where the output voltage is continuously monitored and compared against the target voltage. The error signal generated by this comparison drives the push-pull output stage, enabling rapid correction of voltage deviations. The feedback loop works in conjunction with the bi-directional drivers to quickly source or sink current as needed, achieving fast response times while maintaining stability through closed-loop control. This feedback system manages the complexity of rapid adjustment by using automated error correction rather than manual control.
Data Source
AI summary
A push-pull Low Dropout (LDO) voltage regulator is provided. An instantaneous output voltage of the push-pull LDO voltage regulator is compared with a first reference voltage and a first output based on comparing the first reference voltage with the instantaneous output voltage is provided. The instantaneous output voltage of the push-pull LDO voltage regulator is compared with a second reference voltage and a second output based on comparing the instantaneous output voltage with the second reference voltage is provided. One or more bi-directional drivers of a plurality of bi-directional drivers of the push-pull LDO voltage regulator are driven based on the first output and the second output. The plurality of bi-directional drives provide the predetermined output voltage.