Off-Chip Driver Circuit With Wide Resistance Matching and Low Pad Capacitance
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Solution Overview
Problem
Semiconductor devices face issues with increased capacitance values on connecting pads due to the use of multiple parallel pull-up and pull-down drivers to address offset phenomena in the fab process, leading to slowed response speeds.
Innovation Solution
An off-chip driver and driving circuit that provide a matching resistance value with a wide range while minimizing capacitance by using a main current source circuit and base circuit in parallel, allowing for a single driver to adjust resistance values based on current, thus reducing the need for parallel connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple parallel pull-up drivers and pull-down drivers are used to address offset phenomena, then the matching resistance value can be provided, but the capacitance value on the connecting pad increases
Solution Approach 1:
The patent merges multiple parallel pull-up drivers and pull-down drivers into a single driver that provides both pull-up and pull-down functions. This single driver uses a current source circuit to generate a main current value that can be controlled to provide the required matching resistance value, thereby reducing the number of parallel connections and lowering the capacitance value on the connecting pad while maintaining reliability
2Reliability
If multiple parallel pull-up drivers and pull-down drivers are used to address offset phenomena, then the matching resistance value can be provided, but the response speed of the semiconductor device slows down
Solution Approach 1:
The patent merges multiple parallel drivers into a single driver with a controllable current source. By concentrating the driving function in one element rather than multiple parallel elements, the RC time constant is reduced, thereby improving response speed while still providing the necessary matching resistance value through controlled current adjustment
3Manufacturing precision
If more pull-up drivers and pull-down drivers are used in parallel, then the offset phenomenon in the fab process is solved, but the device area increases
Solution Approach 1:
The patent merges multiple drivers into a single integrated driver structure that occupies less area. The current source circuit and base circuit are combined in one driver unit, significantly reducing the device area compared to having multiple parallel drivers, while still compensating for offset phenomena through controlled current adjustment
Solution Approach 2:
The patent uses parameter changes by controlling the main current value generated by the current source circuit. By adjusting this current parameter, the driver can compensate for offset phenomena in the fab process without requiring multiple physical driver elements, thereby maintaining manufacturing precision while reducing device area
Data Source
AI summary
An off-chip driver (OCD), a pull-up driver of the OCD and the pull-down driver of the OCD are provided. The pull-up driver includes a main current source circuit and a main base circuit. The main current source circuit is connected between a connecting pad and a high reference voltage. The main current source circuit provides a main current value in response to a main control signal. The matching resistance value is associated with the main current value. The main base circuit is connected to the main current source circuit in parallel, and determines a base value of the matching resistance value.