Cascade of AG203-63G oscillates

[mkuczma]

Hi, I am buiding a hi gain RF receiver. I need more than 100 dB of gain. My wanted to use a cascade of 5 AG203-63G RF amplifiers and two other LNA at the front end. I build a test board for the AG amplifiers. If I measure only one almplifier block ewerything works fine, the measured gain looks exactly like in datasheet. When two amplifiers are connected in series, ther are oscillations on output of second one. First seems to be working properly. if I connect 5 of them in series sometimes only first works correct, sometimes first and second. The rest of them oscillate.

I supply them by 5V from a LT3042.
This is my schematic and the board layout:

The board has 4 layer, L2 and L3 are grounds, L4 is used for 5V supply and ground.

I tried different decoupling capacitors, supply isolation by adding ferrite bead for each amplifiers and there was no changes.

Do you have any ideas how to makes them work?

Marcin

[MJT]

A few ideas:

1. Add decoupling for higher frequencies, say 68pF, to each stage at the supply pin
2. Ensure you use very low input power to avoid overdriving later stages. Above -20dBm is enough to cause compression at 1GHz
3. Measure the isolation from output to input. You may need to improve it, for example by adding shielding