Transmitter Driver Circuit Linearity Compensation
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Solution Overview
Problem
Conventional transmitters for integrated circuits face challenges in maintaining linearity of driving current due to the use of passive resistors, which increases parasitic capacitance and limits high-speed operation.
Innovation Solution
The transmitter design incorporates main and auxiliary drivers, each comprising PMOS and NMOS transistors, to compensate for non-linear driving current characteristics without using passive resistors, ensuring linearity and high-speed operation by enabling or disabling drivers based on output node voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If passive resistors are used to secure linearity of driving current, then linearity is improved, but parasitic capacitance increases and speed deteriorates
Solution Approach 1:
The invention extracts and removes the passive resistors from the transmitter circuit. By replacing the resistor-based linearity control with an auxiliary driver that uses transistors (Q3, Q4) controlled by a sensing voltage, the circuit achieves linearity without the parasitic capacitance introduced by passive resistors, thereby improving operating speed while maintaining current linearity.
Solution Approach 2:
The invention introduces an auxiliary driver as an intermediary component between the main driver and the output node. This auxiliary driver uses transistors Q3 and Q4 along with a sensing voltage to indirectly control the driving current characteristics, providing linearity compensation without directly using passive resistors in the main signal path, thus avoiding their parasitic effects.
2Manufacturing precision
If passive resistors are used to secure linearity of driving current, then linearity is improved, but device complexity increases
Solution Approach 1:
The invention merges the linearity control function with the existing driver transistors Q1 and Q2 by adding an auxiliary driver that shares the same output node. The auxiliary driver's transistors Q3 and Q4 are integrated into the existing circuit topology, and the sensing voltage is derived from the same power supply network, combining multiple functions into a unified circuit structure rather than adding separate linearity control components.
Solution Approach 2:
The auxiliary driver serves multiple functions: it compensates for non-linear driving current characteristics, maintains linearity across different operating conditions, and works seamlessly with both the pull-up and pull-down drivers. The same auxiliary driver structure can be applied to different driver configurations, providing a universal solution for linearity improvement without requiring circuit-specific passive resistors.
Data Source
AI summary
A transmitter includes: a main pull-up driver suitable for pull-up driving an output node; and an auxiliary pull-up driver suitable for pull-up driving the output node based on a voltage of the output node, wherein the auxiliary pull-up driver compensates for non-linear driving current characteristics of the main pull-up driver.