EMRFD Message Archive 4778

Message Date From Subject
4778 2010-06-13 07:06:40 Brooke Clarke Power Amp Design
Hi David:

It turns out that the most advanced method of analyzing power amplifiers
that I've dealt with is based on using an Agilent
*L*arge *S*ignal *N*etwork *A*nalyzer (LSNA). It measures amplitude and
phase of a fundamental signal and a large number of it's harmonics.
It's done my taking time domain samples and doing a lot of high power
math. The calibration system requires a comb generator that's very special.

One way of thinking about the power amplifier case is to picture the I-V
curve for the active device and look at the dynamic trajectory of the
operating point. To get the best power added efficiency that operating
point needs to stay near the zero volt or zero current axis. When the
operating point moves away from both of these points it's drawing real
One of the driving applications was the output stage in a cell phone
where you want to most RF power and the lowest battery drain.

Have Fun,

Brooke Clarke, N6GCE

> 1. Power Amp Design Article
> Posted by: "drmail377" drmail377@yahoo.com drmail377
> Date: Sun Jun 13, 2010 12:29 am ((PDT))
> FWIW, There is a nice article in the May 2010 issue of High Frequency Electronics entitled "Power Amplifier Design Fundamentals: more Notes from the Pages of History". This is a multi-part article. The May edition has a nice review of load lines and load pull contours.
> The magazine may be freely downloaded as a .pdf here:
> http://www.highfrequencyelectronics.com/
> Best 73's, David WB4ONA