Schmitt Trigger Input Receiver With Virtual Supply Level Shifting
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Solution Overview
Problem
Existing input receiver circuits face challenges in meeting low power consumption and voltage compatibility requirements, particularly in integrated circuit devices with different power supply domains, leading to issues with static current consumption and circuit area occupancy.
Innovation Solution
A Schmitt trigger circuit with a reference voltage generator and a virtual power supply node, coupled with transistors and capacitors, is used to reduce static current consumption and improve voltage compatibility, allowing the circuit to operate over a wide range of supply voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional input receiver circuit is used to interface between different power supply domains, then voltage compatibility is achieved, but static current consumption increases
Solution Approach 1:
The patent introduces a virtual power supply node as an intermediary between the I/O power supply domain and the core power supply domain. This virtual node acts as a mediator that enables voltage level translation and signal level shifting without requiring direct coupling between the two domains, thereby reducing static current consumption while maintaining voltage compatibility.
Solution Approach 2:
The patent segments the power supply domains by introducing a virtual power supply node that separates the I/O power supply domain from the core power supply domain. This segmentation allows each domain to operate independently at its own voltage levels, eliminating the need for high static current flow between domains while maintaining proper signal level translation.
2Adaptability or versatility
If the I/O power supply domain voltage is higher than the core power supply domain voltage, then voltage level translation is required, but circuit complexity increases
Solution Approach 1:
The virtual power supply node serves as an intermediary that simplifies voltage level translation by providing a reference point for level shifters. Instead of complex direct translation circuits between widely different voltage domains, the virtual node enables simpler translation stages that operate relative to this intermediate reference, reducing overall circuit complexity.
Solution Approach 2:
The level shifter circuits are configured to automatically adjust signal levels based on the virtual power supply node voltage. The circuit self-regulates the voltage translation by using the virtual node as a dynamic reference, eliminating the need for external control mechanisms or complex configuration circuits, thereby reducing overall system complexity.
3Loss of energy
If a virtual power supply node is introduced to reduce static current, then power consumption decreases, but circuit area increases
Solution Approach 1:
The virtual power supply node serves multiple functions simultaneously: it acts as a power supply reference, a signal level reference, and a current blocking element. By consolidating these multiple functions into a single circuit element, the patent minimizes the additional area required while achieving significant power consumption reduction through the elimination of static current paths.
Solution Approach 2:
The patent merges the power supply function with the signal reference function by combining the virtual power supply node with the biasing networks of the Schmitt trigger and level shifters. This merging eliminates the need for separate reference voltage generators and current blocking circuits, thereby reducing the overall circuit area overhead while maintaining low power consumption.
Data Source
AI summary
An input signal having a logic low level at a first voltage and a logic high level at a second voltage is received by a Schmitt trigger. A voltage generator outputs a reference voltage generated from a third voltage that is higher than the second voltage. A first transistor coupled between the third voltage and a power supply node of the Schmitt trigger is biased by the reference voltage to apply a fourth voltage to the power supply node of the Schmitt trigger that is dependent on the reference voltage. The reference voltage has a value which causes the fourth voltage to be less than or equal to the second voltage. A second transistor coupled between the input signal and the input of the Schmitt trigger circuit is also biased by the reference voltage to control the logic high level voltage of the input signal at the Schmitt trigger.