Gain decrease in the in-band of a common emitter amplifier.

[inass bouhichia]

Hi guys,

I have designed a simple common emitter using the BFU660F as shown in the schematic, in the simulation i had a flat gain from approximatly 3MHz to 100Mhz, However during mesurements, i had a gain difference of 1.5dB between the gain at 3MHz and 100MHz. And i have yet to find an explanation for this and would appreciate any ideas.

Thank you in advanve.

 

[LvW]

To be honest - I am surprised that the difference is not larger than 1.5 dB.
At frequencies as large as 100 Mhz you have to consider many parasitic effects that are not included in the simulation setup.

 

[WHONOES]

How are you measuring it?