Capacitor-Free Series Regulator Circuit for Stable Voltage
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Solution Overview
Problem
Conventional Low Drop Out (LDO) regulators require large capacitors for stable output voltage, which are costly and hinder integration in semiconductor devices, especially in portable devices where space and cost are concerns.
Innovation Solution
A series regulator circuit that uses current sources, resistors, and NMOS/PMOS transistors to generate a stable output voltage without voltage feedback or large capacitors, utilizing current mirrors to maintain reference voltages and proportional currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large bypass capacitor is used to ensure stable output voltage, then the stability of the regulator is improved, but the cost increases and integration on chip becomes difficult
Solution Approach 1:
The patent extracts the capacitor component from the regulator circuit, eliminating the need for large bypass capacitors by redesigning the control mechanism to use active circuit elements (transistors, operational amplifiers) that provide stability through feedback control rather than passive energy storage
Solution Approach 2:
The patent replaces the passive mechanical/electrical system (large capacitor) with an active electronic control system using transistors and operational amplifiers that achieve stability through dynamic feedback adjustment rather than static energy storage
2Reliability
If a large bypass capacitor is used to ensure stable operation, then the stability of the regulator is improved, but the cost increases
Solution Approach 1:
The patent removes the expensive large capacitor component from the bill of materials and replaces it with standard-value capacitors and active circuit elements, significantly reducing component cost while maintaining stability through active feedback control
Solution Approach 2:
The patent changes the operating parameters of the circuit by using active feedback control with operational amplifiers and transistors to achieve stability, allowing the use of smaller, cheaper capacitors instead of requiring large, expensive ones
Data Source
AI summary
A low drop out series regulator circuit for generating an output voltage that does not rely on voltage feedback or require a capacitor for stable operation includes first and second current sources connected in series between a supply voltage and ground. A resistor is connected between and in series with the first and second current sources, and a reference voltage is generated across the resistor by the current from the first current source. A first transistor is connected between the ground and a first node located between the resistor and the second current source. A current mirror circuit is connected between the supply voltage and the first transistor. A current sense transistor is connected between the current mirror circuit and an output terminal. An output transistor is connected between the supply voltage and the output terminal. The output voltage generated at the output terminal is equal to the reference voltage.