Questions / statements on this design.
First one is how the? drafter of the schematic - not the original designer came to? his Av? results
For instance the? input transformer has a voltage gain of? 2 and? a power gain of slightly less than one.
so as a? log ratio surely the? voltage gain is? +3 dbB ? But he uses? 20 log? V2/ V1 type formula I guess and he's getting? 6 dB
THe reason this is intriguing? is I want to see where his? Av of? 13.4 for the first video op amp comes from.
I 'd say that? the way to analyse this is? to replace teh 180 R feed back resistor with two 90Rs and a? virtual tap to GND.? That's because
it is a fully balanced circuit.??
So Av would? be? 332 /90? ? +1, using the std form for an inverting in put? FB amplifier.? THis gives a voltage gain of 4.7
I we use the Incorrect formula of? ? 20 Log? 4.7? ?we get 13.4? as a the? Av as a logarithmic gain. This aligns with his table.
This query is more about? the correct way of analysing the? performance of the RF amp than picking holes in whatever formulation he?
used for the? logarithmic voltage gain.??
any comments. ?
The other comment which I wills save is those ballasting resistors on the output? - they seem to be required as per the TI? datasheet for this chip.
Timothy Fidler