u/gosow9

I have following lna design. Now I'm not sure if I should devide the input gnd and output gnd of the lna part.

schema of lna

lna part one gnd pout all gnd layers

I have a 6 layer rogers 4350B stack with following purpose

1. Signal / gnd

2. gnd

3. signal

4. gnd

5. pwr

6. gnd

Since the pcb is in a cryostat we produce it without soldermask. Its mounted on a copper cold finger that will conect the last plane. thus I just made the last gnd plane one hughe pour. Lines are 50Ohm coplanaer wave guides.

The frequency of the lna design is optimized for 10Mhz -3Ghz. but the diramics behavoir for under 100Mhz is not known since its a extrapolation.

Any inputs are welcome

Hi all

I need to design an broadband amplifier for my thesis that works inside of a cryostat at 2Kelvin. Now I'm testing a design that has a bias T in the beginning to bias an superconducting sensor. The frequencies from the sensor are from 10MHz up to 3GHz.

Since I want to avoid weird behavior of my components I use C0G capacitors and air core coils for my inductance. As they should be more or less robost at such temperatures.

Does somebody has some tips for the bias T? I currently look at cone shaped coils from coilcraft. Does somebody has other devices in mind I could check out? Thanks for any input.

If the community has interest I can also share the sim and designs