Envelope Tracking Current Bias Circuit with DC Offset Removal

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Solution Overview

Problem

Existing envelope tracking (ET) current bias circuits include unnecessary direct current (DC) offset current in the ET current output, limiting the efficiency and accuracy of power amplifiers.

Innovation Solution

An ET current bias circuit is designed with a second voltage/current converting circuit that generates a DC offset compensation current to remove the DC offset from the ET current, using a circuit structure similar to the first voltage/current converting circuit, and an arithmetic circuit to calculate and adjust the ET bias current, ensuring accurate ET current generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the envelope detection circuit provides ET voltage and the voltage/current converting circuit converts it to ET current, then the power amplifier can reduce current consumption by tracking the envelope signal, but the DC offset voltage in the ET voltage is converted into unnecessary DC offset current that limits efficiency and accuracy

Engineering Contradiction:

Improvecurrent consumptionVSAvoidET current accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The voltage/current converting circuit is divided into two separate converting circuits: a first voltage/current converting circuit that converts reference voltage to DC current, and a second voltage/current converting circuit that converts ET voltage to ET current. This segmentation allows independent processing and offset removal capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An offset removal circuit is introduced as an intermediary component between the second voltage/current converting circuit and the arithmetic circuit. This intermediary removes the DC offset current from the ET current before it is used, preventing the harmful effect while preserving the useful envelope tracking function.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If the voltage/current converting circuit directly converts ET voltage to ET current, then the circuit structure remains simple, but the DC offset current cannot be removed and accumulates in the ET current output

Engineering Contradiction:

Improvecircuit structureVSAvoidDC offset current

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The DC offset current, which is initially a harmful factor, is converted into a beneficial element by using it as a reference for the offset removal circuit. The first voltage/current converting circuit generates DC current that mirrors the offset characteristics, enabling the offset removal circuit to eliminate the harmful DC offset from the ET current while maintaining circuit simplicity.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The circuit uses parameter changes in the control signals VC1 and VC2 to adjust the DC current and DC offset compensation current dynamically. By changing the parameters (control signal levels) based on operating conditions, the circuit can adaptively remove offset while maintaining simple structure.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution effectively removes the DC offset current from the ET current, providing an accurate and efficient ET bias current that improves the performance of power amplifiers by reducing unnecessary current consumption and enhancing signal linearity.

Implementation Method 1

an envelope detection circuit configured to detect an envelope signal of an input signal

Methodology Applied

Scientific EffectEnvelope detection:

Implementation Method 2

a first voltage/current converting circuit configured to convert a reference voltage into a direct current (DC) current

Methodology Applied

Scientific EffectVoltage to current conversion:

Implementation Method 3

an offset removal circuit configured to remove the DC offset current included in the ET current by using the DC offset compensation current

Methodology Applied

Scientific EffectCurrent subtraction:

Data Source

PatentUS10270395B2Envelope tracking current bias circuit with offset removal function and power amplifier

Publication Date: 2019.04.23 SAMSUNG ELECTRO MECHANICS CO LTD

AI summary

An envelope tracking (ET) current bias circuit comprises an envelope detection circuit detecting an ET voltage from an input signal; a first voltage/current converting circuit converting a reference voltage into a direct current (DC) current and adjusting the DC current according to a first control signal; a second voltage/current converting circuit converting the ET voltage into an ET current, adjusting the ET current according to a second control signal, and removing a DC offset current from the ET current to provide an offset compensated ET current; and an arithmetic circuit calculating levels of the offset compensated ET current and the DC current to generate an ET bias current.