[time-nuts] Buffer amplifier, OP Amp, vs MMIC, vs discrete?

[Richard (Rick) Karlquist]

Some vendors say "LF-1GHz" etc instead of the misleading "DC".
True DC coupled amplifiers are a different universe.  They
must be differential.  Search for differential amplifier IC'S
from the usual suspects.  You will find that the NF will be
at least 7 dB and up.  I'm  not exactly sure why, but I have
never seen an exception so it must be baked into the cake.

There are over-the-top bias TEE's that go from audio to GHz
from extreme vendors such as Picosecond Pulse Labs.  Again,
those bias tees are a different universe than ordinary ones.
Probably too pricey for hobby use.

We used to have to mess around with all this stuff when
I worked for Agilent Labs.

Rick N6RK


On 4/4/2020 3:02 AM, David C. Partridge wrote:
> If you look at the way the power is supplied to and output is taken from an MMIC there's no way that I can see that they could go all the way to DC as there's always a capacitor in the output ...
> 
> I got all excited a while back when I considered an MMIC for a project because the spec said DC-xGHz.   Sadly the specified circuit for using it meant there's no way it could get the DC, though a large output capacitor in parallel with a RF cap would allow audio to GHz.   Hmmm where did I leave the 1 MegaFarad capacitor.
> 
> D.