Dual-Bootstrap PWM Driver for High-Side and Low-Side Matching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional open-loop PWM amplifiers suffer from high non-linearity due to mismatches between high-side and low-side drivers, leading to increased total harmonic distortion and in-band noise.
Innovation Solution
A driver system comprising two n-type field-effect transistors and capacitors that track and correct for resistance mismatches between the transistors, implemented in an open-loop PWM driver stage with high-side and low-side bootstrap capacitors to maintain matched gate-to-source voltages and correct for offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional open-loop PWM amplifiers are used, then device complexity is reduced, but non-linearity increases due to mismatch between high-side and low-side drivers
Solution Approach 1:
The patent introduces a feedback mechanism where the output signal is fed back to the bootstrap capacitors to dynamically adjust and equalize the gate-to-source voltages of high-side and low-side drivers, compensating for mismatches without requiring a full closed-loop architecture
Solution Approach 2:
The patent dynamically adjusts the bootstrap capacitor values based on the output signal characteristics, changing the electrical parameters of the driver circuit to maintain matched gate-to-source voltages under varying operating conditions
2Use of energy by moving object
If open-loop PWM driver is implemented, then power efficiency is improved, but total harmonic distortion increases due to driver mismatch
Solution Approach 1:
The patent uses bootstrap capacitors as intermediary elements that mediate between the output signal and the gate-to-source voltage of the drivers, isolating the mismatch effects while maintaining the open-loop power efficiency
3Ease of manufacture
If simple open-loop driver configuration is used, then ease of manufacture is improved, but in-band noise increases due to non-linearity
Solution Approach 1:
The patent implements a selective feedback path that only affects the bootstrap capacitor charging, leaving the main amplification path open-loop, thereby reducing in-band noise while maintaining manufacturing simplicity
Data Source
AI summary
A driver system may include a first n-type field-effect transistor coupled at its non-gate terminals between an output of the driver system and a first terminal of a supply voltage and configured to drive the output when the first n-type field-effect transistor is activated, a second n-type field-effect transistor coupled at its non-gate terminals between an output of the driver system and a second terminal of the supply voltage and configured to drive the output when the second n-type field-effect transistor is activated, a high-side capacitor coupled to the output of the driver system, and a low-side capacitor coupled to the second terminal of the supply voltage, wherein the high-side capacitor and the low-side capacitor are configured to track and correct for mismatches between a first resistance of the first n-type field-effect transistor and a second resistance of the second n-type field-effect transistor.