Breaking News
Comments
Newest First | Oldest First | Threaded View
JeremyHendy
User Rank
Rookie
re: Understand and characterize envelope-tracking power amplifiers
JeremyHendy   1/16/2012 2:26:02 PM
NO RATINGS
Almost all ET PAs are used in Class AB mode. And while the AM:PM distortion can't directly be controlled by the supply voltage, our experience with the vast majority of handset PAs is that correcting the AM:AM using IsoGain ET also brings the phase response into line. And simple memoryless correction of AM:PM ("DPD-Lite") is an increasingly common capability of the latest handset chipsets.

WKetel
User Rank
Rookie
re: Understand and characterize envelope-tracking power amplifiers
WKetel   1/12/2012 3:09:06 PM
NO RATINGS
I agree that an envelope-tracking amplifier does not have to be a "class C" amplifier, although that would provide the greatest efficiency, it could easily cause some distortion. The other comment is certainly valid, which is that it takes a great deal more effort to design an amplifier that will deliver a satisfactory level of distortion at various operating voltages. Phase modulation certainly does happen and it must be compensated for in order for the distortion level to be acceptable, and designing the correct compensation will certainly add a lot to the design effort.

XRF
User Rank
Rookie
re: Understand and characterize envelope-tracking power amplifiers
XRF   1/10/2012 5:28:31 PM
NO RATINGS
The surface response of an ET PA is more complex than a simple 3D RF-input vs battery-supply. Phase pushing and pulling will occur in such a 3D ET control solution. One comment on the transistion region to be noted; it is the same break-point as system modulation pre-distortion uses. There are two other break-points needed to arrive at the most effective ET modulation efficiency which are not mentioned in the text.

psi123
User Rank
Rookie
re: Understand and characterize envelope-tracking power amplifiers
psi123   1/5/2012 7:29:50 PM
NO RATINGS
The objection of the envelope tracking transmitters is to improve efficiency of the output signal. It is collecting the input signal data and replaces it with something that we do not know at the time.

psi123
User Rank
Rookie
re: Understand and characterize envelope-tracking power amplifiers
psi123   1/5/2012 12:01:00 AM
NO RATINGS
WKetel: Envelope tracking does not have to have Class "C" drivers and setting back the clock of the system. I do not want it to be represented as one of the unfinished ideas.

WKetel
User Rank
Rookie
re: Understand and characterize envelope-tracking power amplifiers
WKetel   1/4/2012 9:32:00 PM
NO RATINGS
Envelope tracking reminds me of the two modulated stages in an AM transmitter with class "C" driver and output stages. Much more efficient than anything linear. But more demanding on the output filtering section.



EE Life
Frankenstein's Fix, Teardowns, Sideshows, Design Contests, Reader Content & More
Max Maxfield

Creating New Faceplates for Antique Analog Meters
Max Maxfield
40 comments
I've currently got a couple of hobby projects on the go that feature the use of antique analog meters. For example, there's my Inamorata Prognostication Engine and its companion, the ...

EDN Staff

11 Summer Vacation Spots for Engineers
EDN Staff
11 comments
This collection of places from technology history, museums, and modern marvels is a roadmap for an engineering adventure that will take you around the world. Here are just a few spots ...

Glen Chenier

Engineers Solve Analog/Digital Problem, Invent Creative Expletives
Glen Chenier
11 comments
- An analog engineer and a digital engineer join forces, use their respective skills, and pull a few bunnies out of a hat to troubleshoot a system with which they are completely ...

Larry Desjardin

Engineers Should Study Finance: 5 Reasons Why
Larry Desjardin
45 comments
I'm a big proponent of engineers learning financial basics. Why? Because engineers are making decisions all the time, in multiple ways. Having a good financial understanding guides these ...

Flash Poll
Top Comments of the Week
Like Us on Facebook
EE Times on Twitter
EE Times Twitter Feed

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)