LDO Regulator Input Current Compensation Circuit
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Solution Overview
Problem
Low-dropout (LDO) regulators face performance issues due to voltage drops across components, particularly when the input current of the transistor affects the output voltage, especially when the supply voltage is close to the output voltage, leading to undesirable regulation of the output voltage.
Innovation Solution
Incorporating a compensation circuit with a second resistor connected to the pre-charge buffer, which generates a compensation current that offsets the voltage drop across a first resistor in the noise filter, ensuring the output voltage remains consistent with the reference voltage by creating an equal voltage drop in the feedback loop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a noise filter with a first resistor is connected between the pre-charge buffer and the output stage, then noise performance is improved, but voltage drop across the first resistor affects output voltage regulation
Solution Approach 1:
The compensation circuit creates a feedback mechanism by sensing the voltage drop across the first resistor and generating a compensating voltage through the second resistor. This feedback loop adjusts the pre-charge buffer output to offset the voltage drop, thereby maintaining accurate output voltage regulation while preserving the noise filtering function.
Solution Approach 2:
The second resistor acts as an intermediary element that translates the voltage drop information into a compensating signal. By placing the second resistor in the feedback path of the pre-charge buffer, it mediates between the noise filter and the output stage, allowing the system to compensate for the voltage drop without removing the noise filter.
2Reliability
If the supply voltage is close to the output voltage, then dropout performance is improved, but voltage drops across components significantly affect output voltage
Solution Approach 1:
The compensation circuit provides real-time feedback correction for voltage drops that become significant in dropout conditions. When supply voltage is close to output voltage, the feedback mechanism continuously monitors and compensates for component voltage drops, maintaining precise output voltage regulation even in the low-headroom dropout region.
Solution Approach 2:
The circuit dynamically adjusts the effective resistance in the feedback path by using the second resistor to compensate for voltage drops. This parameter change allows the system to maintain precise voltage regulation across varying supply voltage conditions, particularly when operating close to the dropout boundary where voltage headroom is limited.
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
This configuration improves noise performance and maintains the output voltage stability even when the supply voltage is close to the output voltage, enhancing the overall performance of the LDO regulator by compensating for the input current's influence on the output stage.
Implementation Method 1
The compensation circuit is configured to provide a compensation current that produces a first voltage drop across the second resistor, where the first voltage drop offsets a second voltage drop produced by an input current of the transistor across the first resistor
Data Source
AI summary
According to an aspect, a low-dropout (LDO) regulator includes a pre-charge buffer, an output stage, and a noise filter connected between the pre-charge buffer and the output stage of the LDO regulator. The noise filter includes a first resistor. The LDO regulator includes a transistor configured as an input to the output stage, and a compensation circuit connected to an input of the pre-charge buffer. The compensation circuit includes a second resistor. The compensation circuit is configured to provide a compensation current that produces a first voltage drop across the second resistor, where the first voltage drop offsets a second voltage drop produced by an input current of the transistor across the first resistor.