On-Chip Voltage Regulator with Virtual Voltage Transition Control
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Solution Overview
Problem
Reduced threshold voltage in CMOS circuits increases standby current due to sub-threshold leakage, leading to significant battery drain in inactive modes of portable devices, and conventional power switch implementations can cause inrush current damage during mode transitions.
Innovation Solution
A semiconductor device with a power switch array and a monitor that simulates a critical path to generate a virtual voltage, allowing for controlled voltage adjustments across a circuit, mitigating inrush current and reducing leakage by incremental voltage transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the threshold voltage of CMOS devices is reduced to maintain propagation delay performance, then the circuit can operate at reduced power levels, but the standby current increases exponentially due to sub-threshold leakage
Solution Approach 1:
The power supply connection is segmented into multiple discrete power switches (headswitches and footswitches) that can be independently controlled. This segmentation allows selective disconnection of power to specific circuit blocks during standby mode, isolating the leakage current to only the essential control circuits rather than the entire chip, thereby reducing total standby power consumption.
Solution Approach 2:
The invention changes the voltage parameter dynamically by using power switches to disconnect the power supply voltage from circuit blocks during standby mode. This parameter change (from active voltage to disconnected state) eliminates sub-threshold leakage current in the disconnected blocks, resolving the contradiction between low operating power and high standby current.
2Loss of energy
If power switches are used to disconnect logic gates from power supply during inactive mode, then leakage current is reduced, but inrush current can damage the circuit during mode transitions
Solution Approach 1:
The invention applies preliminary action by gradually transitioning the voltage level before complete disconnection. The power switches are controlled to ramp down the voltage incrementally rather than switching abruptly, which prevents inrush current during the transition to standby mode. Similarly, voltage is ramped up gradually before full power connection, preventing inrush current during activation.
Solution Approach 2:
The invention introduces dynamic control of the power switches to manage the transition process. Instead of static on/off switching, the power switches are dynamically controlled to adjust voltage levels progressively, making the transition smooth and preventing harmful inrush currents while maintaining the leakage reduction benefit.
3Loss of energy
If conventional power switches with high threshold voltage are used, then leakage current is reduced, but the voltage collapse across connected circuit causes operational issues
Solution Approach 1:
The invention introduces virtual ground nodes as intermediaries between the power switches and the circuit blocks. These virtual grounds maintain a stable reference potential even when power is disconnected, preventing voltage collapse. The intermediary virtual ground allows the power switches to disconnect power for leakage reduction while maintaining voltage stability for proper circuit operation.
Data Source
AI summary
A semiconductor device having an on-chip voltage regulator to control on-chip voltage regulation and methods for on-chip voltage regulation are disclosed. A semiconductor device includes a circuit positioned between a ground bus and a power bus. A power switch array is positioned between the circuit and one of the ground bus or the power bus to generate a virtual voltage across the circuit. A monitor is positioned between the ground bus and the power bus. The monitor is configured to simulate a critical path of the circuit and to output a voltage adjust signal based on an output of the simulated critical path. A controller is configured to receive the voltage adjust signal and to output a control signal to the power switch array to control the virtual voltage.