Semiconductor Storage Back Gate Control for Power Loss Reduction
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Solution Overview
Problem
Existing semiconductor storage systems using two power source paths for magnetoresistance change elements face power loss due to unintentional current flow caused by forward bias at the back gate of the low-side current source transistor when the high-side power source path starts supplying current.
Innovation Solution
A semiconductor storage system is designed with two power source paths, each including a power gate transistor and a current source transistor in series, connected by a connection path. A switch element is inserted between the connection path and the storage element, and the back gate of the low-side current source transistor is coupled to its internal node, thereby suppressing the Well-Forward phenomenon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-side power source path starts supplying current, then writing capability is improved, but unintentional current flows to the low-side current source transistor causing power loss
Solution Approach 1:
A back gate control circuit is introduced as an intermediary between the high-side power source path and the low-side current source transistor. This control circuit monitors the state of the high-side path and dynamically adjusts the back gate voltage of the low-side transistor to prevent forward bias, thereby eliminating unintentional current flow while preserving the high-side path's writing capability.
Solution Approach 2:
The back gate of the low-side current source transistor is configured to receive a control signal that preemptively counteracts the forward bias effect before unintentional current can flow. When the high-side power source path is activated, the control circuit applies a reverse bias voltage to the back gate in advance, preventing the harmful forward bias condition from occurring in the first place.
2Adaptability or versatility
If two power source paths are used, then writing into all magnetoresistance change elements is achieved, but power loss occurs due to Well-Forward phenomenon
Solution Approach 1:
A back gate control circuit is introduced as an intermediary between the high-side power source path and the low-side current source transistor. This control circuit monitors the state of the high-side path and dynamically adjusts the back gate voltage of the low-side transistor to prevent forward bias, thereby eliminating unintentional current flow while preserving the high-side path's writing capability.
Solution Approach 2:
The electrical parameter (back gate voltage) of the low-side current source transistor is dynamically changed based on the operational state of the high-side power source path. By adjusting the back gate voltage to maintain reverse bias or zero bias conditions, the transistor's conductivity is controlled to prevent power loss while allowing both power source paths to function for comprehensive writing coverage.
Data Source
AI summary
A semiconductor storage according to an embodiment of the present disclosure includes two power source paths, and a connection path that connects the power source paths. Each of the power source paths includes a power gate transistor and a current source transistor which are coupled in series. The connection path connects ends of the respective power source paths on a side of the current source transistor. The semiconductor storage further includes a storage element, and a switch element inserted between the connection path and the storage element. A back gate is coupled to an internal node in the current source transistor provided in a low-side path of the two power source paths.