2nd order High Pass butterworth filter

[imrankhanPNU]

Hello,
Could anyone review my 2nd order Butterworth HPF design? I have mentioned design details along with schematics and initial results.

Design specifications for 2nd HPF: Cutoff frequency= 100Mhz, Design method: by considering equal component, Input signal= 10V,120MHz, sinosidal.

Design specification for OPAMP: Slew rate= 5V/usec , CL=10pF, ICMR+= 4.5V, ICMR-=1.5V , Vdd=5V, GBW>=5MHz, W/L ratio is mentioned with each transistor.

According to the calculations, it should work but I do not know where I am making mistakes...

Thanks

 

[Dominik Przyborowski]

So, you have single stage OTA biased by 50uA loaded by 100pF caps and shorted to ground by 160Ohms resistor. What went wrong?

 

[danadakk]

Something really amiss if you are doing this at 100 Mhz with 5 Mhz GBW G elements ?
Same comment applies to G element slew rate of only 5V / microsecond. That does not
jive with :

What am I missing here ?


Regards, Dana.

 

[BradtheRad]

To check performance of your rolloff curve, apply a sweeping sine wave say, from 1/10 of spec frequency to 10x spec. Output should resemble this simulation of 1st order filter.
Naturally your rolloff curve ought to be steeper since yours is 2nd order.

Notice with my larger R value, less current is gobbled from the source.