Class-D Power Amplifier Feedback Circuit for Common-Mode Jitter
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Solution Overview
Problem
Conventional class-D power amplifiers with low pass filters introduce noise and current issues due to the inclusion of operational amplifiers, which inadvertently increase common-mode jitter.
Innovation Solution
A power amplifier design incorporating an operational amplifier, ramp generators, comparators, inverters, and buffers that utilize a ramp signal to generate decision results and inverted outputs, feeding these back through resistors to reduce common-mode jitter, with specific configurations of PMOS and NMOS transistors to manage input and output ports effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low pass filters with operational amplifiers are introduced to suppress common-mode jitter, then common-mode jitter suppression is improved, but noise and current increase
Solution Approach 1:
The patent extracts and removes the low pass filter component from the feedback path, relying instead on the inherent properties of the switching amplifier and strategic feedback network design to suppress common-mode jitter without introducing additional noise and current
Solution Approach 2:
The patent introduces a feedback network comprising resistors and inverters as an intermediary mechanism to achieve common-mode jitter suppression. This feedback network processes the output signals and feeds back corrected signals to the input, eliminating the need for noisy low pass filters while maintaining effective jitter control
2Reliability
If low pass filters are introduced to suppress common-mode jitter, then common-mode jitter suppression is improved, but device complexity increases
Solution Approach 1:
The patent removes the complex low pass filter structure from the circuit, simplifying the overall design while maintaining common-mode jitter suppression through a more elegant feedback-based approach
Solution Approach 2:
The patent implements a feedback mechanism where output signals are fed back through a network of resistors and inverters to the input stage. This feedback loop automatically corrects common-mode jitter without requiring complex filtering components, achieving suppression with simpler circuitry
Data Source
AI summary
A power amplifier includes an operational amplifier, a ramp generator communicatively coupled to both a first comparator and a second comparator; the first comparator further communicatively coupled to a negative output port of the operational amplifier; the second comparator further communicatively coupled to a positive output port of the operational amplifier; a first inverter communicatively coupled to the first comparator; a second inverter communicatively coupled to the second comparator; wherein the first inverter is communicatively coupled to both a positive input port of the operational amplifier via a first resistor and coupled to a negative input port of the operational amplifier via a fourth resistor; and the second inverter is communicatively coupled to both the positive input port of the operational amplifier via a second resistor and connected to the negative input port of the operational amplifier via a third resistor.