Envelope Tracking Bias Circuit for RF Delay and Bandwidth Switching

Solution Overview

Problem

The delay between the RF signal and the bias voltage or current in power amplifiers, especially at higher frequency bands, leads to RF performance degradation in envelope tracking systems, particularly in LTE applications where high-speed operation is required.

Innovation Solution

An envelope tracking bias circuit that includes an envelope detector, an envelope bandwidth detector, and a bias output circuit, which generates different bias currents based on the frequency band of the RF signal. When the frequency band is high, it uses an average envelope bias mode to reduce magnitude variation, and when it's low, it operates in direct envelope bias mode to minimize delay impact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If direct envelope bias mode is used to minimize delay impact, then response speed is improved, but magnitude variation increases at high frequency bands

Engineering Contradiction:

Improveresponse speedVSAvoidmagnitude variation

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The system dynamically switches between direct envelope bias mode and average envelope bias mode based on the frequency band of the RF signal. The bias mode selector circuit changes the processing mode in real-time according to frequency conditions, making the system adaptable to different operating conditions rather than using a fixed mode.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the processing parameter (bias mode) based on the frequency band parameter. When the frequency band exceeds a reference value, the system switches from direct envelope bias mode to average envelope bias mode, effectively using parameter changes to resolve the contradiction between response speed and magnitude variation.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If average envelope bias mode is used to reduce magnitude variation, then stability is improved, but response speed decreases

Engineering Contradiction:

Improvemagnitude variationVSAvoidresponse speed

Core Design Contradiction:

Stability of the object's compositionVSSpeed

Solution Approach 1:

The system dynamically switches between direct envelope bias mode and average envelope bias mode based on the frequency band of the RF signal. The bias mode selector circuit changes the processing mode in real-time according to frequency conditions, making the system adaptable to different operating conditions rather than using a fixed mode.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the processing parameter (bias mode) based on the frequency band parameter. When the frequency band exceeds a reference value, the system switches from direct envelope bias mode to average envelope bias mode, effectively using parameter changes to resolve the contradiction between response speed and magnitude variation.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If envelope tracking bias is applied to improve RF performance, then output RF performance is improved, but delay between RF signal and bias increases at high frequency bands

Engineering Contradiction:

Improveoutput RF performanceVSAvoiddelay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system dynamically switches between direct envelope bias mode and average envelope bias mode based on the frequency band of the RF signal. The bias mode selector circuit changes the processing mode in real-time according to frequency conditions, making the system adaptable to different operating conditions rather than using a fixed mode.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the processing parameter (bias mode) based on the frequency band parameter. When the frequency band exceeds a reference value, the system switches from direct envelope bias mode to average envelope bias mode, effectively using parameter changes to resolve the contradiction between response speed and magnitude variation.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20240275342A1Envelope tracking bias circuit and envelope tracking bias method thereof

Publication Date: 2024.08.15 SAMSUNG ELECTRO MECHANICS CO LTD

AI summary

An envelope tracking bias circuit that generates a bias current to a power amplifier that amplifies a radio frequency (RF) signal is provided. The envelope tracking bias circuit includes an envelope detector configured to detect an envelope signal of the RF signal; an envelope bandwidth detector configured to detect a frequency band of the envelope signal; and a bias output circuit that generates a bias current based on an average magnitude of the envelope signal when the frequency band of the envelope signal is greater than or equal to a predetermined frequency, and generates a bias current in response to the envelope signal when the frequency band of the envelope signal is lower than the predetermined frequency.