Class G Amplifier Staggered Switching Glitch Reduction
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Solution Overview
Problem
Class G amplifiers experience switching glitches at the crossover point due to abrupt switching between power rails, leading to increased distortion and EMI issues, as existing technologies fail to minimize these glitches effectively.
Innovation Solution
The implementation of a Class G amplifier with multiple parallel amplifier devices and staggered switching between inner and outer power rails, utilizing delay elements to spread the switching process over time, reducing the magnitude and frequency components of glitches within the amplifier's bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If abrupt switching between power rails is used in Class G amplifiers, then switching speed is improved, but switching glitches and distortion increase
Solution Approach 1:
The patent segments the single switching event into multiple smaller switching events by dividing the amplifier output stage into multiple parallel paths (e.g., multiple current mirrors or amplifier devices). Each path switches independently with staggered timing, breaking one large glitch into multiple smaller glitches that are easier to filter and manage.
Solution Approach 2:
The patent applies preliminary action by using delay elements to pre-coordinate the switching timing of each parallel path. Before the main switching event occurs, each path is prepared to switch at slightly different times, ensuring a controlled transition that minimizes glitches while maintaining fast overall switching response.
2Object-generated harmful factors
If multiple parallel amplifier devices with staggered switching are used, then switching glitches are reduced, but device complexity increases
Solution Approach 1:
The patent merges multiple parallel amplifier devices into a unified output structure where all paths converge to the same output node. This combining approach allows the benefits of multiple staggered switching events while maintaining a relatively simple overall architecture that leverages existing amplifier building blocks.
Solution Approach 2:
The patent changes the timing parameter of each parallel path using delay elements, creating staggered switching without fundamentally altering the amplifier device structures. This parameter-based control achieves glitch reduction while keeping the device topology relatively simple and familiar.
3Loss of energy
If Class G amplifiers switch between multiple power rails, then power efficiency is improved, but switching transients and EMI increase
Solution Approach 1:
The patent segments the power rail switching event into multiple smaller transitions across parallel amplifier paths. Each path switches between power rails independently with staggered timing, breaking one large transient into multiple smaller transients that generate less EMI and are easier to manage, while still achieving the power efficiency benefits of Class G operation.
Data Source
AI summary
An improved Class G type amplifier is provided which switches between multiple power rails depending upon the instantaneous amplitude of the input signal versus the power rails without excessive distortion. The low voltage (inner) amplifier includes a plurality of parallel amplifier devices, and the high voltage (outer) amplifier includes a plurality of parallel amplifier devices. A plurality of switches each couples the input signal to either a respective one of the inner amplifier devices or a respective one of the outer amplifier devices. The switches are activated sequentially, such that the switching from inner amplifier devices to outer amplifier devices or vice versa is staggered over time. This avoids having a single, large glitch in the output and spreads multiple smaller glitches over enough time so that some of the radiated glitch energy can fall within frequencies where amplifier feedback circuitry can eliminate its noise. The switches are sequentially activated by a series of delay elements.