Two-Way DVC Linear Regulator With Miller Current Compensation
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Solution Overview
Problem
Existing linear regulators with dynamic voltage control (DVC) capability face slow transitions between power states due to Miller capacitance, resulting in less pronounced power savings.
Innovation Solution
A linear regulator design that includes a current injection circuit to compensate for current flowing through the Miller capacitance, using controllable current sources and sinks, and a programmable voltage divider circuit to achieve fast voltage scaling and reduce silicon area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Miller capacitance is used in the operational amplifier for DVC, then the amplifier can provide gain and stability, but the transitions between power states become slow
Solution Approach 1:
The patent extracts the harmful effect of Miller capacitance by introducing a current injection circuit that actively compensates for the current through the Miller capacitor. This separates the stability function (retained through the Miller capacitor) from the speed limitation (counteracted by the compensation current), allowing both goals to be achieved simultaneously.
Solution Approach 2:
The current injection circuit provides preliminary anti-action by pre-compensating for the current that would otherwise flow through the Miller capacitance and slow down the transition. The compensation current is injected in advance to counteract the slowing effect, enabling faster transitions while maintaining stability.
2Device complexity
If conventional linear regulator design is used, then the circuit is simple, but the silicon area is large and transition speed is slow
Solution Approach 1:
The patent introduces dynamic elements (controllable current sources and programmable voltage divider) that allow the regulator to adapt its behavior based on operating conditions. This dynamic approach enables faster transitions and reduced silicon area while maintaining the fundamental simplicity of the linear regulator architecture.
Solution Approach 2:
The patent changes key parameters of the operational amplifier (current injection, voltage division ratio) to optimize performance. By dynamically adjusting these parameters, the circuit achieves faster transition speeds and reduced silicon area without fundamentally changing the conventional linear regulator structure.
3Loss of energy
If voltage scaling is performed quickly, then power savings are improved, but the Miller capacitance causes slow transitions that reduce power savings
Solution Approach 1:
The patent uses feedback through the voltage divider circuit and operational amplifier to rapidly detect and respond to voltage scaling requirements. The feedback mechanism, enhanced by current injection compensation, enables the system to quickly adjust the output voltage to the desired level, maximizing power savings by achieving the scaled state faster.
Solution Approach 2:
The current injection circuit provides preliminary anti-action against the Miller capacitance effect, enabling faster voltage scaling. This allows the system to quickly transition between power states, thereby improving power savings by reducing the time spent during transition and minimizing energy dissipation during the scaling process.
Data Source
AI summary
A linear regulator which has a pass device coupled between an input voltage level and an output node, a voltage divider circuit for generating a feedback voltage that depends on an output voltage at the output node, and an operational amplifier for controlling the pass device, the operational amplifier receiving the feedback voltage and a reference voltage at its inputs is presented. The operational amplifier has: an input stage that receives the feedback voltage and the reference voltage at its inputs, an amplifier stage that receives an output of the input stage at its input, and a current injection circuit for sourcing current into an intermediate node between the input stage and the amplifier stage, or sinking a current from the intermediate node. The disclosure further relates to a corresponding method of operating a linear regulator.