Bulk-Controlled Switch Circuit for Fast Low-Leakage Voltage Switching
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Solution Overview
Problem
Conventional bulk switching transistor circuits face issues with slow switching and unintended power leakage due to parasitic diode coupling, leading to potential latch-up and inefficiencies in dynamic voltage switching.
Innovation Solution
A bulk-controlled switch circuit is designed with parallel transistors and current mirror circuits, where the gates of transistors are coupled via impedance circuits to form a comparator switch, enabling faster and more accurate switching, and constant current generators introduce hysteresis to prevent false switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional bulk switching circuitry is used with simple transistor switching, then the circuit structure remains simple, but switching speed is slow and parasitic diode leakage occurs
Solution Approach 1:
The bulk switching control is segmented into multiple independent current mirror circuits (first current mirror circuit for source voltage control, second current mirror circuit for drain voltage control). Each current mirror circuit independently controls the bulk voltage of corresponding transistors, enabling faster and more precise switching without requiring a monolithic complex control structure.
Solution Approach 2:
The current mirror circuits are configured to proactively control the bulk voltage before the main switching action occurs. By pre-adjusting the bulk voltage through the current mirrors in response to source or drain voltage changes, the switching speed is enhanced and parasitic leakage is prevented before it can occur.
2Adaptability or versatility
If dynamic bulk switching is implemented to follow variable source and drain voltages, then adaptability is improved, but parasitic diode coupling causes unintended power leakage
Solution Approach 1:
The current mirror circuits provide feedback control for bulk voltage adjustment. The first current mirror circuit monitors source voltage and adjusts the bulk voltage accordingly, while the second current mirror circuit monitors drain voltage and adjusts bulk voltage in response. This feedback mechanism ensures the bulk voltage dynamically adapts to voltage variations while preventing parasitic diode coupling and power leakage.
Solution Approach 2:
The current mirror circuits act as intermediary control elements between the source/drain voltage terminals and the bulk terminal. Instead of directly coupling the bulk to source or drain voltages (which causes parasitic leakage), the current mirrors serve as mediating structures that translate voltage changes into controlled bulk voltage adjustments, eliminating the harmful direct coupling path.
3Ease of operation
If threshold voltage difference is reduced to enable coupling, then voltage control flexibility improves, but leakage through parasitic diodes increases
Solution Approach 1:
The conventional mechanical/threshold-based voltage coupling mechanism is replaced with an electric field-based current mirror control system. Instead of relying on threshold voltage differences to enable coupling (which creates parasitic leakage paths), the invention uses electrically controlled current mirrors that can precisely regulate bulk voltage without creating harmful diode coupling effects.
Data Source
AI summary
According to an aspect, there is provided an apparatus comprising: a bulk-controlled switch circuit comprising a first transistor coupled to a load and having a source coupled to a source voltage and a drain coupled to a drain voltage, a second transistor and a third transistor coupled, in parallel with the first transistor, to one another in series between the source voltage and the drain voltage, wherein a bulk of the first transistor is coupled with bulks of the second transistor and the third transistor, wherein a gate of the second transistor is coupled to the source voltage via a first impedance circuit and a gate of the third transistor is coupled to the drain voltage via a second impedance circuit to form a comparator switch controlled by the source voltage and the drain voltage and to dynamically switch a greater one of the source voltage and the drain voltage to the load; a first current generator circuit and a second current generator circuit; a first current mirror circuit biased by the first current generator circuit, responsive to the source voltage, and configured to trigger the second transistor to couple the source voltage to the load when the source voltage is above the drain voltage; a second current mirror circuit biased by the second current generator circuit, responsive to the drain voltage, and configured to trigger the third transistor to couple the drain voltage to the load when the drain voltage is above the source voltage.