MOS Driver Circuit Slew Rate Control With Impedance Code Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing driver circuits face challenges in achieving desired output slew rates due to manufacturing variability in the slew rate control part and gate driving parts, leading to inconsistent bias voltages and slew rates.
Innovation Solution
The proposed driver circuit includes a current source circuit that generates signals to control the driving ability of the gate control part, using plural transistors connected in parallel with a common resistor and a signal generation part that adjusts the driving ability based on input current, along with a correction code generation part to fine-tune impedance codes and suppress manufacturing variability effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a current source circuit with plural transistors connected in parallel is used to control driving ability, then the output slew rate can be adjusted, but manufacturing variability causes inconsistent bias voltages and slew rates
Solution Approach 1:
The patent implements a feedback mechanism where the actual output slew rate is measured and compared with the target slew rate. Based on this comparison, the control circuit adjusts the impedance codes to compensate for manufacturing variability. This closed-loop feedback ensures that the output slew rate consistently meets the desired specification despite variations in transistor parameters during manufacturing.
Solution Approach 2:
The patent dynamically changes the impedance codes based on measured slew rate performance. By adjusting the impedance parameters in response to actual circuit behavior, the system compensates for manufacturing variations. The impedance codes are modified to optimize the driving ability of the gate control part, ensuring consistent output slew rate across different manufacturing batches.
2Adaptability or versatility
If impedance codes are used to control output impedance, then the driver circuit can be optimized for different loads, but manufacturing variability leads to deviations from desired impedance values
Solution Approach 1:
The patent uses feedback to measure the actual output impedance and compare it with the target impedance value. The measured impedance information is fed back to the control circuit, which adjusts the impedance codes to minimize the difference between actual and desired impedance. This ensures accurate impedance control despite manufacturing variations in the driver circuit components.
3Power
If the gate control part drives multiple output transistors in parallel, then the driving ability can be increased, but variations in transistor parameters cause inconsistent performance
Solution Approach 1:
The patent adjusts the impedance codes to optimize the distribution of driving current among the parallel output transistors. By changing the impedance parameters based on measured performance, the system compensates for transistor parameter variations. This ensures that each transistor contributes consistently to the overall driving ability, maintaining reliable and predictable performance.
Data Source
AI summary
A PMOS output stage and an NMOS output stage of which output impedances are controlled in accordance with impedance codes, a gate control part which drives output transistors held by the PMOS output stage and the NMOS output stage, and a slew rate control part which generates bias voltages to control driving ability of the gate control part based on an input current are included, and manufacturing variability of an input current circuit generating an input current is corrected by using the impedance code by the slew rate control part.