Variable Resistance Reference Voltage Circuit for Power Supply Rejection
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Solution Overview
Problem
Conventional reference voltage circuits face challenges in achieving high power supply rejection (PSR) and fast start-up times due to voltage drops in power distribution networks, often requiring trade-offs between start-up time and power efficiency, which can lead to increased battery drain and cooling requirements.
Innovation Solution
A variable resistance circuit is introduced, coupled with a reference voltage circuit, which includes a voltage detection circuit and a digital-control switch to adjust the output load and impedance, allowing for optimized power supply rejection and start-up time by dynamically changing resistance values during steady-state and start-up modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a filter circuit is added to increase power supply rejection, then PSR is improved, but start-up time increases
Solution Approach 1:
The patent applies dynamics by making the resistance value adjustable based on operating conditions. The variable resistance circuit changes its resistance dynamically - using a first resistance value during start-up mode to minimize start-up time, and a second resistance value during steady-state mode to maximize power supply rejection. This dynamic adaptation resolves the contradiction between fast start-up and high PSR performance.
2Loss of time
If circuit parameters are adjusted to decrease start-up time, then start-up time is improved, but power efficiency deteriorates
Solution Approach 1:
The patent uses dynamics to adjust the resistance value based on the operational phase. During start-up mode, a first resistance value is used to enable fast charging of the output capacitor and quick voltage establishment. During steady-state mode, a second resistance value is used to minimize power consumption. This dynamic parameter adjustment allows the circuit to optimize for speed when needed and for efficiency when stable.
Solution Approach 2:
The patent implements periodic action by switching between different resistance values based on the operational phase. The control circuit periodically transitions from start-up mode to steady-state mode, and the variable resistance circuit相应地 switches between first and second resistance values. This periodic switching allows the system to achieve both fast start-up and low power consumption at different times in the operational cycle.
3Use of energy by moving object
If low current is used to improve power efficiency, then power consumption is reduced, but start-up time increases
Solution Approach 1:
The patent resolves this contradiction by dynamically adjusting the current level based on operational phase. During start-up mode, the variable resistance circuit uses a first resistance value that allows higher current flow to quickly charge the output capacitor and establish the reference voltage. During steady-state mode, the circuit switches to a second resistance value that limits current to minimize power consumption. This dynamic current management enables both fast start-up and low power operation.
Data Source
AI summary
A method and apparatus for power supply rejection in a reference voltage circuit using a variable resistance circuit.