Voltage Regulator Test Circuit for Phase Compensation Capacitors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing voltage regulator testing methods struggle to accurately determine connection failures and capacitance of phase compensation capacitors, especially when the discharge current is smaller than the steady-state current consumption, leading to potential measurement errors.
Innovation Solution
A voltage regulator with a test circuit that switches between normal and test modes, using a switch to make the phase compensation capacitor effective or ineffective, and a constant current source to reduce bias current, allowing for the measurement of voltage waveforms to estimate connection failures and capacitance by comparing phase differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the discharge current is used to measure capacitor connection failure and capacitance, then the measurement can be performed indirectly without direct capacitor measurement, but the measurement accuracy deteriorates when the discharge current is smaller than the steady-state current consumption
Solution Approach 1:
The patent introduces a test circuit as an intermediary system that includes switching elements and current sources to isolate and amplify the discharge current measurement. The test circuit switches between normal operation mode and test mode, and uses constant current sources to enhance the discharge current signal, making it measurable even when smaller than the steady-state current consumption.
2Measurement precision
If testing pad terminals are formed to directly test each element of the phase compensation circuit, then the completeness of capacitors and other elements can be directly verified, but the chip area increases and parasitic capacitance degrades the phase compensation circuit performance
Solution Approach 1:
The patent extracts the testing function from the main circuit by introducing a separate test circuit that can be activated independently. The test circuit includes switching elements that connect test nodes to measurement points only when needed, allowing indirect verification of capacitor completeness without permanently adding testing pad terminals that would increase chip area and introduce parasitic capacitance.
3Quantity of substance
If the phase compensation capacitor has small capacitance value, then the phase compensation circuit can operate with smaller components, but the discharge current becomes very small making it difficult to detect connection failures and measure capacitance
Solution Approach 1:
The patent employs dynamic switching of current sources during the test mode. A constant current source is activated to discharge the phase compensation capacitor, and another constant current source is used to amplify or match the discharge current to a measurable level. This dynamic current management allows accurate measurement of discharge current even when the capacitor has small capacitance value.
Solution Approach 2:
The test circuit changes the current parameters by introducing constant current sources that provide a known discharge current. By controlling the discharge current parameter independently of the capacitor value, the system can measure even very small capacitances accurately. The test mode also changes the operational state of the voltage regulator to isolate the discharge current measurement from the steady-state current consumption.
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
Enables accurate estimation of connection failures and capacitance even for phase compensation capacitors with small discharge currents, improving testing accuracy without the need for direct measurement of the capacitor, and reducing measurement errors.
Implementation Method 1
a constant current source 123
Implementation Method 2
the p-channel type MOS transistor 121 and an n-channel type MOS transistor 122
Implementation Method 3
the phase compensation capacitor 111
Data Source
AI summary
A voltage regulator includes an output voltage terminal which supplies an output voltage having a preset value, a voltage adjustment terminal which detects the output voltage, an error amplifier which compares the output voltage and a reference voltage to control the output voltage, a phase compensation capacitor, a test circuit which switches a normal mode with a test mode to test the phase compensation capacitor, a switch which makes the phase compensation capacitor valid or invalid, and a constant current source which makes a bias current of the error amplifier in the test mode lower than that in the normal mode.