Breaking News
Comments
Oldest First | Newest First | Threaded View
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.

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.

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.

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.

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.

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.



Flash Poll
EE Life
Frankenstein's Fix, Teardowns, Sideshows, Design Contests, Reader Content & More
Engineer's Bookshelf
Caleb Kraft

The Martian: A Delightful Exploration of Math, Mars & Feces
Caleb Kraft
6 comments
To say that Andy Weir's The Martian is an exploration of math, Mars, and feces is a slight simplification. I doubt that the author would have any complaints, though.

The Engineering Life - Around the Web
Caleb Kraft

Surprise TOQ Teardown at EELive!
Caleb Kraft
Post a comment
This year, for EELive! I had a little surprise that I was quite eager to share. Qualcomm had given us a TOQ smart watch in order to award someone a prize. We were given complete freedom to ...

Design Contests & Competitions
Caleb Kraft

Join The Balancing Act With April's Caption Contest
Caleb Kraft
57 comments
Sometimes it can feel like you're really performing in the big tent when presenting your hardware. This month's caption contest exemplifies this wonderfully.

Engineering Investigations
Caleb Kraft

Frankenstein's Fix: The Winners Announced!
Caleb Kraft
8 comments
The Frankenstein's Fix contest for the Tektronix Scope has finally officially come to an end. We had an incredibly amusing live chat earlier today to announce the winners. However, we ...

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)