Voltage Regulator with Segmented Driver Transistors for DRAM
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Solution Overview
Problem
Conventional voltage regulators for semiconductor memories, such as DRAM, face challenges in providing stable and sufficient current supply due to abrupt current consumption during bit line sensing and pre-charge operations, leading to excessive voltage drops and increased manufacturing complexity and cost.
Innovation Solution
A voltage regulator design incorporating a comparing unit, first and second driver transistors, a feedback unit, an auxiliary control unit, and switches to manage voltage and current supply, ensuring stable voltage levels and sufficient current delivery while preventing excessive overshoot or drop-out, using separate control signals for each driver transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional voltage regulator with a single driver transistor and basic feedback is used, then the circuit complexity is low, but the voltage stability and current supply sufficiency deteriorate during abrupt current consumption events
Solution Approach 1:
The patent divides the driver function into two separate driver transistors (first driver transistor and second driver transistor) with distinct control mechanisms. The first driver transistor responds to feedback voltage for steady-state regulation, while the second driver transistor responds to trigger signals for abrupt current events. This segmentation allows each transistor to be optimized for its specific function, improving overall voltage stability without requiring a single overly complex control mechanism.
Solution Approach 2:
The patent implements a trigger signal mechanism that activates the second driver transistor in advance during detected abrupt current consumption events (such as bit line sensing or pre-charge operations). This preliminary action ensures that additional current supply is ready before the voltage drop occurs, maintaining voltage stability during critical operations rather than reacting after the problem arises.
2Productivity
If a single driver transistor is used for voltage regulation, then the device complexity is reduced, but the ability to handle abrupt current consumption and prevent excessive voltage drop deteriorates
Solution Approach 1:
The patent segments the current supply function into two dedicated transistors: the first driver transistor handles steady-state current regulation through feedback control, while the second driver transistor handles abrupt current demands through trigger signal control. This segmentation enables each transistor to be sized and controlled optimally for its specific operational regime, achieving superior current supply capability without requiring one large, inefficient transistor.
Solution Approach 2:
The patent implements dynamic control where the second driver transistor is activated only during detected abrupt current consumption events via trigger signals from the trigger circuit. This dynamic approach allows the system to scale its current supply capability on-demand, achieving high productivity during critical operations while maintaining lower average power consumption and reduced complexity during normal operation.
3Reliability
If feedback control is used for voltage regulation, then voltage stability is improved, but the response speed to abrupt current changes deteriorates due to feedback delay
Solution Approach 1:
The patent introduces a trigger circuit as an intermediary between the load and the second driver transistor. This trigger circuit detects abrupt current consumption events and generates trigger signals that directly activate the second driver transistor, bypassing the feedback delay inherent in the main feedback loop. This intermediary mechanism enables fast response to critical events while the feedback loop continues to maintain steady-state accuracy.
Solution Approach 2:
The trigger circuit performs preliminary detection and activation before the feedback loop can respond to abrupt current changes. By detecting the need for additional current supply and activating the second driver transistor in advance, the system prevents voltage drops rather than correcting them after detection, achieving both fast response and accurate regulation.
Data Source
AI summary
A voltage regulator as a stable power supply to internal circuits in a semiconductor memory device is provided. This regulator includes a comparing unit, a first driver transistor, a feedback unit, an auxiliary control unit, a first switch, a second switch, and a second driver transistor. The comparing unit compares a reference voltage with a feedback signal to control the first driver transistor and maintain the internal power supply at a stable level. The second driver transistor, controlled by the first and second switches responsive to a trigger signal corresponding abrupt current consumptions and the auxiliary control unit responsive to the comparing result, supplies sufficient and appropriate current to the internal circuits and prevents the internal power supply from excessive overshoot and drop-out.