Cross-Coupled Level Shifter for Low-Voltage High-Side Programming
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Solution Overview
Problem
Existing level shifters face challenges in efficiently converting logic signals between different voltage levels, particularly in high voltage applications where power consumption and heat generation are concerns, and there is a need for cost-effective solutions that utilize transistors with near-zero threshold voltages.
Innovation Solution
A level shifter design incorporating cross-coupled input and output transistors with near-zero threshold voltage N channel transistors, which are conductive at low logic high levels and non-conductive at logic low levels, allowing for efficient voltage conversion between high and low voltage logic circuits without additional processing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high voltage programming is used for NVM programming, then programming capability is achieved, but transistor breakdown occurs due to excessive voltage
Solution Approach 1:
The patent introduces a level shifter circuit as an intermediary device between the high voltage NVM programming circuit and the low voltage logic circuitry. This level shifter converts the high voltage programming signal to a compatible low voltage level, allowing the programming voltage to be selectively supplied to NVM without exceeding the breakdown voltage of the logic transistors. The level shifter acts as a mediator that enables high voltage operation while protecting the low voltage logic components.
2Power
If high voltage is used for programming, then NVM programming is enabled, but power consumption and heat generation increase
Solution Approach 1:
The level shifter circuit serves as an intermediary that converts high voltage programming signals to low voltage levels for logic circuit operation. By selectively supplying high voltage only where needed (to NVM programming circuits) and converting it to low voltage for logic operations, the system achieves NVM programming capability while minimizing overall power consumption and heat generation in the logic circuitry.
Solution Approach 2:
The patent applies different voltage levels to different parts of the system: high voltage is applied locally to NVM programming circuits where it is needed, while low voltage is used for logic circuitry. This localized voltage application allows programming capability where required while reducing overall power consumption and heat generation in the majority of the system that operates at low voltage.
3Ease of operation
If near-zero threshold voltage transistors are used, then conduction at low logic high levels is achieved, but transistor cost increases
Solution Approach 1:
The patent changes the threshold voltage parameter of specific transistors (the cross-coupled input transistors) to near-zero values to enable conduction at low logic high levels. This parameter change is applied selectively only to the input transistors that benefit from low-threshold operation, rather than changing all transistors in the circuit, thereby achieving the desired operational characteristic while minimizing the impact on manufacturing cost.
Data Source
AI summary
A level shifter circuit includes first and second cross-coupled P channel transistors, first and second cross-coupled N channel transistors, and first and second inverters. The first and second P channel transistors are coupled to receive a first power supply voltage. The first and second cross-coupled N channel transistors are coupled to the first and second P channel transistors. The first and second inverters are coupled to the first and second N channel transistors and are coupled to receive a second power supply voltage that is lower than the first power supply voltage. The first and second N channel transistors have a lower, substantially zero volts, threshold voltage and can be controlled by a low voltage signal while limiting a leakage current.