High cut-off frequency in CE amplifier

I have a CE amplifier.

With real instrumentation, real circuit I got a high cut-off frequency of about 600 kHz while if I repeat it in PSpice I got about 200 MHz (!)

Same circuit with LT Spice I got about 3,5MHz

The device is 2N3904

I saw in an example provided by LTspice that there is a

100pF capacitor between C and B...

Pheraps Miller effect isn't calculated by Spice?

Thanks in advance.

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Without a schematic we know nothing. And... What is your definition of cut-off frequency? ...Jim Thompson

| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Jim Thompson

Maybe. How this for a start.

  1. Wrong board lay out. (Un calculated Capacitance &/ induction)
1A. Un expected LC taking place.
  1. Wrong type of resistors.
  2. Not putting a local bypass caps in.
  3. Local bypass caps if #3 has been done, aren't using a non inductive type.
  4. Design has to high of R values, but Spice should of picked up on that.
  5. Your transistor is a fake knock off or just something that was around and stamped as so.

  1. The simulator is just wrong! (no surprise there)

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Jamie ha scritto:

This one. Found the issue. Thanks again.

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