era-5 gain problem?

If you're only 1 dB off, that's pretty good shootin' in this business.

The ERA5 tends to have a low Zin, maybe 40 ohms or even a little less, so you can get more gain by fiddling the input match network, if you have one. The output bias network affects gain, too.

Of course, Mini-Circuits occasionally changes the vendor or the process or something, so the ERA5 specs jump around quite a bit anyhow. A lot, actually. If you call Mini-Circuits, they don't know much about the part.

John

Hello Jmariano,

I agree with John, 1 dB is a small deviation (it is even within the specs).

In addition some load and/or source mismatch may change insertion gain. Did you carry out your measurements well below 1 dB gain compression point? Do you use well dimensioned capacitors and RF chokes?

Best regards,

Wim PA3DJS

Hi John and Wilm,

Tank you for your help.

I can live with a 1dB off!

Being new to RF "business", as John pointed out, I was convinced that a deviation of 1dB as a sign of something wrong with my circuit. I was trying to put the blame on the era-5. But if, between impedance mismatches and gain variation, on the era-5 or due to the bias network (among others tings),

Wilm, all measurements are made well below 1dB compression point this time, but, of course, I did that mistake the first time :-)

Regards,

Jmariano

If you need exact gain, you can tune the device current and swing a few dB. That will alsi change the impedances! These mmics are just Darlington transistors and aren't very smart.

One part I really like is the SGA-3586. It's SiGe, low noise, lots of gain, and Zin can be nailed to exactly 50 ohms by tweaking the operating current. And, unlike the ERA5, it doesn't keep changing. I have some graphs somewhere...

John

Well, unfortunately i'm using a already made board, so i'm stuck with the eras. Maybe next time i'll follow your suggestion. Tanks any way.