Distributed Envelope Tracking Amplifier Layout for Low Trace Inductance
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Solution Overview
Problem
Existing envelope tracking (ET) amplifier circuits suffer from efficiency and linearity degradation due to trace inductance associated with long coupling distances between the amplifier and ET voltage circuits, particularly at higher modulation bandwidths.
Innovation Solution
A distributed ET amplifier circuit is implemented where the amplifier circuit is co-located with the ET voltage circuit to reduce trace inductance, using interface circuitry to receive ET target voltage and supply voltages, and an ET voltage circuit generates a modulated voltage based on these inputs to improve efficiency and linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the amplifier circuit is separated from the ET voltage circuit, then the device complexity is reduced and ease of manufacture is improved, but the trace inductance increases causing efficiency and linearity degradation
Solution Approach 1:
The system is divided into separate amplifier circuit and ET voltage circuit modules that can be independently designed and manufactured, yet when implemented together they achieve low trace inductance through optimized coupling. This segmentation allows manufacturing flexibility while maintaining performance through precise physical arrangement of the separated components.
2Ease of manufacture
If the coupling distance between amplifier circuit and ET voltage circuit is increased, then the ease of operation and manufacturing is improved, but the trace inductance increases causing modulated voltage degradation
Solution Approach 1:
The coupling trace between amplifier circuit and ET voltage circuit is optimized locally with reduced inductance design, while other parts of the system maintain standard layout. This localized optimization ensures high voltage precision where critical (at the coupling point) without requiring global redesign of the entire system, balancing manufacturing ease with signal integrity.
3Productivity
If the modulation bandwidth is increased to achieve higher data rates, then the productivity is improved, but the efficiency and linearity degradation due to trace inductance becomes more severe
Solution Approach 1:
The ET voltage circuit proactively generates time-variant supply voltages that anticipate and compensate for the effects of trace inductance before they can degrade the signal. By pre-adjusting the supply voltage based on the modulation bandwidth requirements, the system maintains amplifier linearity and efficiency even at high data rates where inductance effects would normally be severe.
Data Source
AI summary
A distributed envelope tracking (ET) amplifier circuit and related apparatus are provided. The distributed ET amplifier apparatus includes an amplifier circuit configured to amplify a radio frequency (RF) signal based on a modulated voltage. In examples discussed herein, the amplifier circuit is co-located with an ET voltage circuit configured to supply the modulated voltage such that a trace inductance between the amplifier circuit and the ET voltage circuit can be reduced to below a defined threshold. By co-locating the amplifier circuit with the ET voltage circuit to reduce a coupling distance between the amplifier circuit and the ET voltage circuit and thus the trace inductance associated with the coupling distance, it may be possible to reduce degradation in the modulated voltage. As a result, it may be possible to improve efficiency and maintain linearity in the amplifier circuit, particularly when the RF signal is modulated at a higher modulation bandwidth.