Compensated Voltage Regulator Circuit for Parasitic Capacitance
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Solution Overview
Problem
Voltage regulators face challenges in maintaining stability and accuracy due to component mismatch, finite gain of error amplifiers, and external noise, leading to significant variations in output voltage, which are not effectively addressed by existing technologies.
Innovation Solution
A voltage regulator design incorporating a first and second amplifier with a current mirror and a compensation network that includes passive and active components to reduce variations caused by parasitic capacitance and supply voltage fluctuations, improving power supply rejection (PSR).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage regulator uses conventional amplifier and current mirror structures, then the circuit is simple and easy to manufacture, but the output voltage is significantly affected by supply voltage disturbances and parasitic capacitance
Solution Approach 1:
The patent introduces an intermediary compensation network between the current mirror and the load. This network includes a compensation capacitor connected to the output node and a compensation resistor connected to the input of the current mirror. The intermediary network isolates the sensitive current mirror from supply voltage disturbances and parasitic capacitance effects, thereby improving output voltage stability without requiring complete redesign of the basic regulator structure.
Solution Approach 2:
The voltage regulator is segmented into distinct functional blocks: the main regulation path (amplifier and current mirror), the compensation network (separate capacitor and resistor components), and the feedback path. This segmentation allows the compensation network to be added independently to address PSR issues without modifying the core regulation mechanism, maintaining manufacturing simplicity while improving reliability.
2Ease of manufacture
If the regulator structure is simplified to reduce complexity, then manufacturing is easier, but power supply rejection capability deteriorates
Solution Approach 1:
The compensation network acts as an intermediary filtering stage that can be added to conventional regulator designs. The compensation capacitor and resistor are standard passive components that are easy to manufacture and integrate. They provide supply voltage rejection by filtering out high-frequency disturbances before they reach the sensitive current mirror, improving PSR without complicating the manufacturing process.
Solution Approach 2:
The compensation network performs preliminary filtering of supply voltage disturbances before they can affect the current mirror and output voltage. The compensation capacitor charges and discharges in response to supply variations, proactively counteracting disturbances before they propagate through the regulator. This preliminary action enhances power supply rejection while keeping the circuit structure simple and manufacturable.
3Reliability
If compensation networks with multiple components are added to improve PSR, then output voltage stability improves, but device complexity increases
Solution Approach 1:
The patent applies partial compensation by using a single capacitor and a single resistor in the compensation network, rather than complex multi-component filters. This partial action provides sufficient PSR improvement for most applications while minimizing the increase in device complexity. The compensation values are optimized to provide adequate filtering without over-engineering the solution.
Solution Approach 2:
The compensation network serves multiple functions simultaneously: it filters supply voltage disturbances, compensates for parasitic capacitance effects, and stabilizes the output node. This multi-functionality achieves improved voltage regulation accuracy without proportionally increasing complexity, as a single capacitor and resistor perform multiple protective and stabilizing roles in the regulator circuit.
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
The compensation network effectively mitigates output current and voltage variations, enhancing the stability and accuracy of the regulated voltage, thereby improving the power supply rejection ratio (PSR) of the voltage regulator.
Implementation Method 1
the transistor has a parasitic capacitance between the second current terminal and the gate
Implementation Method 2
a compensation network comprising at least one passive component, wherein the compensation network is coupled to the input of the current mirror to reduce variations in an output current
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A voltage regulator and method. The voltage regulator includes a first amplifier having: a first input couplable to a reference voltage; a second input coupled to a feedback path; a current mirror; first and second branches coupled to an input and output of the current mirror. A node of the second branch forms an output of the first amplifier. The voltage regulator includes a second amplifier comprising a transistor having: a first terminal couplable to a supply voltage; a gate coupled to the output of the first amplifier; and a second terminal coupled to an output of the voltage regulator. The feedback path is coupled to the output of the voltage regulator. The voltage regulator includes a compensation network having at least one passive component to reduce variations in an output current of the voltage regulator caused by the parasitic capacitance of the transistor and variations in the supply voltage.