Level Shifter Bias Generation for Thick-Oxide Gate Protection
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Solution Overview
Problem
Challenges arise in driving thick-oxide transistors in level shifting circuits due to reduced minimum feature sizes, leading to unreliable output signals and device failures.
Innovation Solution
A self-protection bias generator circuit generates amplified signals to drive thick-oxide transistors, protecting thin-oxide transistors and ensuring reliable output voltage ratios without additional bias voltage sources, reducing power consumption and maintaining compatibility with various logic processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thick-oxide transistors are used in level shifting circuits to handle higher voltages, then voltage handling capability is improved, but device reliability deteriorates due to reduced minimum feature sizes causing unreliable output signals and device failures
Solution Approach 1:
The patent introduces a self-protection bias generator circuit as an intermediary component that generates high bias voltages to drive the gates of thick-oxide transistors. This mediator circuit ensures proper voltage levels are applied to control the thick-oxide transistors reliably, resolving the contradiction between voltage handling capability and device reliability by providing the necessary gate drive voltage without directly modifying the transistor structure itself.
Solution Approach 2:
The patent changes the electrical parameters of the circuit by generating dynamic bias voltages that adapt to the operating conditions. The self-protection bias generator adjusts the gate voltage levels to match the specific voltage domain requirements, enabling thick-oxide transistors to operate reliably across different voltage domains while maintaining device integrity despite reduced feature sizes.
2Reliability
If additional bias voltage sources are added to drive thick-oxide transistors, then transistor control reliability is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent merges the bias generation functionality directly into the level shifting circuit by integrating the self-protection bias generator within the same circuit block. This consolidation eliminates the need for separate external bias voltage sources, reducing overall device complexity while maintaining reliable transistor control through the generated high bias voltages.
Solution Approach 2:
The self-protection bias generator is designed to automatically generate the required high bias voltages without external intervention or additional control circuits. The circuit self-regulates to provide appropriate gate drive voltages to the thick-oxide transistors, eliminating the need for complex external biasing arrangements and reducing overall system complexity.
3Reliability
If additional bias voltage sources are added to drive thick-oxide transistors, then transistor control reliability is improved, but power consumption increases
Solution Approach 1:
The self-protection bias generator employs periodic switching action through complementary transistor pairs that alternately charge and discharge capacitance to generate the required high bias voltages. This periodic operation allows the circuit to deliver high peak voltages when needed while consuming minimal average power, maintaining transistor control reliability without proportionally increasing overall power consumption.
Solution Approach 2:
The bias generation circuit dynamically adjusts its operation based on the instantaneous requirements of the thick-oxide transistors. The circuit activates bias generation only when voltage transitions are required, rather than maintaining continuous high voltage output, thereby achieving reliable transistor control during critical moments while minimizing overall power consumption through dynamic, on-demand operation.
Data Source
AI summary
A semiconductor device and a method of operating the semiconductor device are disclosed. In one aspect, the semiconductor device includes a level shifting circuit configured to generate an output voltage in a second voltage domain corresponding to an input signal in a first voltage domain. The level shifting circuit includes a thick-oxide transistor and a thin-oxide transistor. The semiconductor device includes a bias generating circuit operatively coupled to the level shifting circuit and configured to generate a bias voltage substantially higher than a voltage of the input signal, and provide the bias voltage to a gate of the thick-oxide transistor, causing the level shifting circuit to generate the output voltage.