Interface Circuit Switching for Process-Variation Signal Integrity
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Solution Overview
Problem
Interface circuits with weak pull-up structures fail to maintain output signal integrity due to process variations, leading to failed signal identification by external devices.
Innovation Solution
Incorporating a first switch controlled by logic circuits to isolate the first transistor during output signal generation, allowing a second transistor to pull down the signal without competing with the first transistor, thereby minimizing the impact of process variations on waveform quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If transistors MP1 and MN1 are coupled in series to generate output signal, then the circuit structure is simple, but process variation causes output signal amplitude to be insufficient and signal identification to fail
Solution Approach 1:
The patent segments the pull-up function by introducing a first switch controlled by a first control signal, separating it from the first transistor. This allows independent control of the pull-up path, ensuring that process variations in the transistor do not affect the output signal quality when the switch is activated.
Solution Approach 2:
The first switch acts as an intermediary between the first transistor and the output node. When activated, it provides a controlled connection that overrides the weak pull-up effect of the first transistor, ensuring reliable output signal generation regardless of transistor parameter variations.
2Use of energy by moving object
If first transistor provides weak pull-up function, then power consumption is reduced, but output signal amplitude becomes insufficient under process variation
Solution Approach 1:
The patent introduces dynamic control through the first switch and first control signal. The pull-up strength can be dynamically adjusted: the switch provides strong pull-up when needed for signal integrity, while the weak pull-up transistor operates when power savings are prioritized, adapting to different operational requirements.
3Power
If second transistor pulls down output signal, then low voltage output is achieved, but competition with first transistor reduces pull-down amplitude
Solution Approach 1:
The patent segments the pull-up function by introducing a first switch controlled by a first control signal, separating it from the first transistor. This allows independent control of the pull-up path, ensuring that process variations in the transistor do not affect the output signal quality when the switch is activated.
Solution Approach 2:
The first switch acts as an intermediary between the first transistor and the output node. When activated, it provides a controlled connection that overrides the weak pull-up effect of the first transistor, ensuring reliable output signal generation regardless of transistor parameter variations.
Data Source
AI summary
The interface circuit includes a first transistor, a second transistor, a first switch, a first logic circuit and a second logic circuit. The first transistor is controlled by a enable signal. The second transistor is controlled by a first control signal. The first switch is coupled between a second end of the first transistor and the output end of the interface circuit, wherein the first switch is controlled by a second control signal. The first logic circuit generates the first control signal according to the enable signal and at least one indication signal. The second logic circuit generates the second control signal according to the first control signal and the enable signal.