The Class B amplifier - basics and simulation (1/2)

[@pserra2]

Hi! Just a quick tip, that might be useful: in LTspice, you can plot measurements vs step parameters. If you open the error log, right click on its window, then there is an option on the context menu for plotting measurements. Hop you find this useful

[@LightningHelix101]

Need to come back and watch these later, but these are a true asset. Let me know if you ever want an extra set of hands to build simulations or brainstorm test fixtures.

[@bigg2441]

These videos are always great to watch and really informative. You teach very well. Many thanks.

[@vincei4252]

Excellent explanation especially the matched NPN phase splitter / combiner topologies.

[@acestudioscouk-Ace-G0ACE]

Great tuition as usual, thanks for making these videos.

[@m1geo]

Excellent as always! Keen for part 2.

[@olivierconet7995]

Very nicely explained, thanks. I am going to try this bifilar transformer configuration right away (for my few mW WSPR beacon). I can't wait for the next video !

[@nickst2797]

I hope more classes are coming next. Like AB...

[@gkdresden]

In fact these are all current amplifiers only. The voltage amplification is always less or equal to 1.

[@naelnassar9330]

Thanks for your Excellent Explanation, If I have RF high power Amplifier Class C Can I changed to class AB

[@vincei4252]

@FesZ how do you model the bifilar transformers in LTSpice? This will be a game changer for me to be able to model some circuits that I've seen with trifilar windings that confuse the heck out of me.

[@FesZElectronics]

Well, its a 1:1 (or 1:1:1 for the trifilar) transformer - so it can be modeled like any other transformer with a "K" statment (no "." at the begining). A 1:1 100uH trafo is built with 2 100uH inductors, say L1 and L2 and the statement "k l1 l2 1" (for an ideal coupling factor of 1); for trifilar, its the same, just add the 3rd inductor to the K statement.

[@fakulol0186]

Very good

[@jj74qformerlyjailbreak3]

Hey Fez. What software are you using to plot these signals? I really like your in-depth explanations. You have taught me lots. I appreciate your inspiring teaching style and analysis. God Bless Friend.

[@FesZElectronics]

I use LTspice for all my simulations. Its a free software.

[@jj74qformerlyjailbreak3]

@@FesZElectronics I’ll check it out. Thanks for your reply. God Bless.

[@AllboroLCD]

Is it safe to say that a Class A, B, & A/B amp PCB could essentially look identical to the eye? The only real difference would be a few resistor values?

[@FesZElectronics]

This is true with AB and B, but with A its not just a difference of component values - With class A, only 1 transistor receives the input signal, while the other acts like a constant current source. Now "to the eye" of course you can make all of them look identical, but in the schematic there will be differences.

[@sinclair8811]

​@@FesZElectronics Hello, when are you going to produce next video about class B amplifier?

[@Theineluctable_SOME_CANT]

Technically, these transistors are both operating in class C because their conduction angle IS LESS THAN 180 degrees. Class B is 180 degrees as you said but did not get right. Amateur.