Parallel Power Gating Switches for Constant Voltage Drop
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Solution Overview
Problem
Modern integrated circuits face challenges in minimizing voltage drop while maintaining low current leakage and die area impact in power gating switches, as increasing voltage is not feasible and large transistors increase leakage, making it difficult to keep voltage drop constant over varying current ranges.
Innovation Solution
A switching arrangement with a plurality of individually controllable elementary switches connected in parallel, dynamically controlled by a controller to adjust impedance based on current intensity, ensuring a substantially constant voltage drop across the power gating switch by varying the number of closed switches according to current levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the power switch transistor is made large to minimize voltage drop, then the voltage drop decreases, but the die area and leakage current increase
Solution Approach 1:
The power switch is divided into multiple elementary switches connected in parallel, each controlled independently by control signals. This segmentation allows dynamic adjustment of the total on-resistance by selectively enabling or disabling individual elementary switches, thereby minimizing voltage drop during high current operation while maintaining smaller individual transistor sizes that reduce leakage current.
Solution Approach 2:
The impedance of the power switch is dynamically adjusted by varying the number of closed elementary switches based on the intensity of the current flowing through the switch. During high current operation, more switches are closed to reduce impedance and voltage drop. During low current operation, fewer switches are closed to minimize leakage current, making the switch characteristics adaptive to operating conditions.
2Loss of energy
If a single large power switch is used to minimize voltage drop, then the voltage drop decreases, but the die area increases
Solution Approach 1:
The power switch functionality is segmented into multiple elementary switches that can be independently controlled. This allows the total switch capacity to be distributed across multiple smaller transistor instances rather than requiring one large transistor, thereby achieving the same or better voltage drop performance with reduced overall die area utilization and improved layout efficiency.
Solution Approach 2:
The system dynamically adjusts the number of active elementary switches based on current intensity requirements. During high current operation, all or most switches are activated to provide low impedance. During low current operation, only the necessary number of switches are activated, allowing the unused switch area to be effectively excluded from the active conduction path, thus reducing the functional die area requirement.
3Loss of energy
If the voltage of the voltage source is increased to compensate for voltage drop, then the voltage drop is compensated, but the junction voltage may exceed the maximum voltage allowed by the manufacturing process
Solution Approach 1:
The system dynamically adjusts the impedance of the power switch by varying the number of closed elementary switches based on the actual current intensity. This dynamic impedance adjustment compensates for voltage drop under varying load conditions without requiring an increase in the voltage source, thereby maintaining junction voltages within the maximum limits specified by the manufacturing process across all operating conditions.
Data Source
AI summary
There is disclosed a switching arrangement comprising a switch with a plurality of individually controllable elementary switches connected in parallel between a first supply rail and a second supply rail. Each of the elementary switches can be in either one of a closed state and an open state independently of the others. A controller is adapted to dynamically control the closing or opening of the elementary switches, depending on the intensity of a current flowing through the switch. The number of elementary switches in the closed state is variable. The higher is the intensity of the current, the higher the number of elementary switches in the closed state. Thus, the impedance of the switch decreases when the current increases, and vice versa, and the voltage drop across the switch may be kept substantially constant.