Memory Voltage Monitor with Bridge Switch for Low-Leakage Sensing
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Solution Overview
Problem
The existing memory devices face inaccuracies in sensing voltage due to leakage currents generated by the pull-up and pull-down switches in the off-chip driver, which affect the accuracy of the sensing voltage on the connecting pad.
Innovation Solution
A voltage monitor is introduced that includes a voltage divider, a bridge switch, and an off-chip driver (OCD) with control switches, where the control switch is turned off in the test mode to reduce leakage currents, thereby improving the accuracy of the sensing voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the pull-up switch and pull-down switch are turned off in test mode, then the leakage current is decreased, but the sensing voltage accuracy deteriorates
Solution Approach 1:
The patent divides the switching function into two separate components: a bridge switch for mode selection and control switches for leakage reduction. This segmentation allows the bridge switch to connect the sensing node to the connecting pad in test mode while the control switches can be turned off to reduce leakage current, resolving the contradiction between maintaining sensing accuracy and reducing leakage.
Solution Approach 2:
The bridge switch acts as an intermediary between the sensing node and the connecting pad. In test mode, it enables the connection while allowing the control switches to be disabled, thereby mediating between the need for accurate sensing voltage transmission and the need to minimize leakage current from the pull-up and pull-down switches.
2Loss of energy
If the control switch is turned off in test mode, then the leakage current in OCD is decreased, but the number of pads increases
Solution Approach 1:
The connecting pad serves multiple functions: it is used for normal data signal transmission during operation mode and for sensing voltage monitoring during test mode. The bridge switch enables this multi-functionality by routing the sensing voltage to the connecting pad without requiring a dedicated separate pad, thus reducing the total number of pads while still allowing leakage reduction through control switch management.
3Measurement precision
If the bridge switch is turned on to monitor internal voltage, then the sensing voltage can be measured, but leakage current flows through the OCD
Solution Approach 1:
The patent segments the switching control into two independent parts: the bridge switch that enables voltage monitoring by connecting the sensing node to the connecting pad, and the control switches that manage the leakage current path. This allows the bridge switch to be on for measurement while the control switches can be off to prevent leakage current flow through the OCD.
Solution Approach 2:
The control switches act as intermediaries that can be disabled to block leakage current paths while the bridge switch maintains the sensing voltage connection. This intermediary control mechanism allows simultaneous achievement of accurate voltage monitoring and leakage current reduction.
Data Source
AI summary
A voltage monitor is provided. The voltage monitor includes a voltage divider, a bridge switch and an off-chip driver (OCD). The voltage divider receives an internal voltage in the memory device, and divides the internal voltage to generate a sensing voltage on a sensing node. The bridge switch is coupled between the sensing node and a connecting pad. The OCD includes a control switch, a pull-up switch and a pull-down switch. A first terminal of the control switch is coupled to a high reference voltage. The pull-up switch is coupled between a second terminal of the control switch and the connecting pad. The pull-down switch is coupled between the connecting pad and a low reference voltage. The bridge switch is turned on in a test mode. The control switch, the pull-up switch and the pull-down switch are turned off in the test mode.