Active Power Splitter

[ge]

Could someone suggest references/examples to designing active power splitters. I have some experience with BJT & FET amplifiers but am unsure of the correct topography to use (cascode/feedback, distributed, etc). The patent on-line lack details (of course). My dream is as much of the 500-3000MHz band as I can cover. Low gain, Low power ( << 27dBm), teens isolation & return loss. ...It's a nice dream.

tnx,
GE

 

[biff44]

I did an active balun once, with one input off the drain, and one output off the source as in a voltage follower (dc resistor to ground). had about that bandwidth as I recall

 

[ge]

Thanks Biff. Did you have much trouble with matching?

 

[biff44]

I do not remember any. You can vary the source and drains resistors to make the match more like 50 ohms.

 

[albbg]

Possibly you are insterested in this article:

https://www.jpier.org/PIERC/pierc18/19.10101004.pdf

 

[ge]

Thanks biff44 & albbg. Article POWER SPLITTER ARCHITECTURES AND APPLICATIONS has only one reference to active power splitters and it is a MMIC. I'm uncertain about the bandwidth. It sounds as if biff44 used a differential power splitter as shown in Figure 3? ... as compared to distributed or cascode. Both distributed and cascode has issues with complexity, package parasitic and size when built using discrete. I need to learn more (as usual).

 

[Bob60]

Probably Wilkinson` s are not so wide band as you required, almost decade. Typically up 20%.

 

[ge]

A Wilkinson can have multi-octave response but is relatively large for low frequencies... also, an amplifier is required to recover the 3dB loss per split.

 

[FvM]

A Wilkinson can have multi-octave response but is relatively large for low frequencies... also, an amplifier is required to recover the 3dB loss per split.

Means what? Obviously 3 dB (ideal power splitter) upto 6 dB (lossy resistive splitter) can't be avoided by a splitter. If you intend zero loss and an amplifier is needed anyway, you might prefer the simple resistive splitter.

 

[ge]

My last comment was in reference to a Wilkinson, i.e. is large when used at lower frequencies and for wide bandwidths. If I was to trade-off DC current, Isolation and/or RF power, a simple resistive splitter and amplifier would be the way to go. If I can build an active splitter smaller with comparable specifications to a Wilkinson, it would takeup less circuit board real estate. Everyone wants more. Resistive splitter is the smallest for the bandwidth but isolation is the trade-off.

 

[FvM]

Separate output amplifiers can improve isolation.

 

[ge]

What is "separate output amplifiers"?

Oh, you mean "two" amplifiers on the output of the splitter. Everything is a trade-off.