Switching Voltage Regulator Control Using Series Pass MOSFETs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing high-voltage switch circuits for memory applications rely on high-voltage rating transistors, which require thick gate oxide, large area occupation, and dedicated manufacturing steps, increasing costs.
Innovation Solution
A switch circuit design that uses only low-voltage rating transistors by implementing a series configuration of pass devices and elevator circuits, allowing the circuit to manage high voltages (0 V to 5 V) without needing high-voltage rating devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-voltage rating transistors are used to handle high voltages (0 V to 5 V), then the circuit can switch between high voltage and low voltage, but the transistor requires thick gate oxide, large area occupation, and dedicated manufacturing steps, increasing costs
Solution Approach 1:
The circuit is segmented into multiple low-voltage transistors arranged in series, where each transistor handles only a portion of the total voltage. This segmentation allows each transistor to be manufactured with standard thin gate oxide, avoiding the need for expensive high-voltage transistors with thick gate oxide and dedicated manufacturing steps
Solution Approach 2:
Elevator circuits are introduced as intermediary voltage-shifting stages between the control signals and the pass transistors. These elevator circuits translate low-voltage control signals into appropriate voltage levels for controlling the series-connected transistors, enabling low-voltage transistors to effectively switch high-voltage signals
2Reliability
If high-voltage rating transistors are used, then the circuit can operate at high voltages, but the transistor occupies large area
Solution Approach 1:
By dividing the high-voltage switching function across multiple low-voltage transistors connected in series, each transistor operates at a lower voltage and requires less area than a single high-voltage transistor would require. The cumulative area of multiple small transistors is less than the area of one large high-voltage transistor
3Reliability
If high-voltage rating transistors are used, then the circuit can switch high voltages, but dedicated manufacturing steps and masks are required, increasing manufacturing complexity
Solution Approach 1:
The segmentation approach allows all transistors to be manufactured using standard low-voltage process steps and masks, eliminating the need for dedicated high-voltage manufacturing steps. This reduces manufacturing process complexity while achieving the same high-voltage switching capability through proper circuit configuration
Data Source
AI summary
A switch circuit includes a first and a second input nodes to receive a first and a second input voltages, and an output node to produce an output voltage switchable between the first and second input voltages. A first and a second pass devices are arranged in series between the first input node and the output node. A third and a fourth pass devices are arranged in series between the second input node and the output node. A first, a second, a third, and a fourth elevator circuits control, respectively, the first, second, third, and fourth pass devices. The first elevator circuit is biased between the first input voltage and a shifted ground voltage. The third elevator circuit is biased between the second input voltage and a ground voltage. The second and fourth elevator circuits are biased between the output voltage and an elevated ground voltage.