I have a signal for which I want to cutoff signal till around 3 MHz. Here is my circuit diagram.
The calculated cut-off frequency is 3.4 MHz. But when I use it, is just does not work, it seems to pass all frequencies. I am not using any load, I am just using the probe to measure the voltage across the inductor. Vin is the output from a Colpits oscillator.
Here is a frequency domain snapshot from my oscilloscope. Yellow is the input and green is the output. The reddish vertical line is where frequency is 3.17 MHz, and green vertical line is 0MHz.
I have tried lot of stuff to work it out. But nothing seems to work. In low pass mode things work fine, but in high pass mode nothing seems to work. Your guidance will be greatly appreciated.
Capacitor datasheet (Class II): http://www.mouser.com/ds/2/212/F3101_Aximax-461059.pdf