CMOS Schmitt Trigger Receiver Using Thin Oxide Level Shifting
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Solution Overview
Problem
The integration of thick oxide devices and thin oxide devices on the same die becomes increasingly difficult and costly, especially in advanced field-effect transistor technologies like GAAFET and MBCFET, due to the need for extra masks and larger layout areas, including keep out zones, which complicates the fabrication process.
Innovation Solution
A Schmitt trigger circuit designed and manufactured using only thin oxide FET devices, which eliminates the need for integrating thick oxide devices and reduces costs by eliminating extra masks and keep out zones, while providing a layout and manufacturing-friendly solution suitable for GAAFET and MBCFET technologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If thick oxide devices and thin oxide devices are integrated on the same die, then both I/O circuits and core logic circuits can be fulfilled, but fabrication becomes increasingly difficult and costly due to extra masks and larger layout areas
Solution Approach 1:
The patent extracts the thick oxide device requirement by implementing a level shifter circuit using only thin oxide devices. The level shifter converts high voltage I/O signals to low voltage core logic signals, eliminating the need for separate thick oxide devices while maintaining both I/O and core logic functionality on the same die.
Solution Approach 2:
The thin oxide devices are made universal by designing them to handle multiple functions: they serve as both core logic circuit elements and I/O interface elements through the level shifter configuration. This multi-functionality allows a single device type to fulfill previously required separate thick oxide and thin oxide device roles.
2Adaptability or versatility
If thick oxide devices and thin oxide devices are integrated on the same die, then both I/O circuits and core logic circuits can be fulfilled, but layout area increases due to keep out zones
Solution Approach 1:
The patent removes the need for keep out zones by extracting the thick oxide device requirement entirely. The level shifter circuit implemented with thin oxide devices eliminates the physical separation requirements between thick and thin oxide devices, allowing compact layout without restricted zones.
3Object-affected harmful factors
If thick oxide devices are used in I/O circuits, then high voltage signals can be handled, but device complexity increases due to multiple device types
Solution Approach 1:
The patent changes the voltage parameter handling by using thin oxide devices with carefully controlled gate voltages. The level shifter architecture ensures that thin oxide devices never experience drain-to-gate voltages exceeding their breakdown threshold, allowing them to handle high voltage I/O signals without requiring thick oxide construction.
Data Source
AI summary
A device including an inverter circuit, a hysteresis control circuit, and a high-side input level shifter. The inverter circuit having an output and including at least two series connected PMOS transistors connected, at the output, in series to at least two series connected NMOS transistors. The hysteresis control circuit coupled to the output to provide feedback to the at least two series connected PMOS transistors and to the at least two series connected NMOS transistors. The high-side input level shifter connected to gates of the at least two PMOS transistors and configured to shift a low level of an input signal to a higher level and provide the higher level to one or more of the gates of the at least two PMOS transistors.