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I'm trying to build a Cascode amplifier on ads but I think I have a problem with my tank oscilator. Here's the complete circuit

Cascode Circuit on ADS

The inductor is an air-core inductor from coilcraft and the transistor is a bc547. The problem with this circuit is the output:

vout

Which is barelly oscilating at all. Here's the input for comparisson:

vin and vout plot

Can anyone help me diagnose this ? The ressonance frequency is 250kHz (which I think is what is causing me trouble).

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    \$\begingroup\$ 53 uF? Drop the capacitor 3 or 4 orders of magnitude and increase L likewise. Or replace the tuned circuit with a current source. \$\endgroup\$
    – user16324
    Commented Nov 20, 2022 at 12:49
  • \$\begingroup\$ Unfortunatelly, I have limited Inductors at hand, this is the highest one (Inductance wise) of them that can sustain a good Q at 250kHz. Maybe I will try something else then. \$\endgroup\$
    – Gevezo
    Commented Nov 20, 2022 at 13:09
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    \$\begingroup\$ Inductors are easy; wind your own. \$\endgroup\$
    – user16324
    Commented Nov 20, 2022 at 14:01
  • \$\begingroup\$ Note that the load is "generally" wired with a serial capacitor ... \$\endgroup\$
    – Antonio51
    Commented Nov 20, 2022 at 14:30

1 Answer 1

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A 53 μF tank capacitor is more suitable for sub-audio filtering. It's completely inappropriate for an amplifier operating at 250 kHz.

Something like 4.05 nF and 100 μH is more like the values you need for your tank circuit.

Other than that, you biasing levels look good to go.

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