1. Home
  2. Electronics Computer-Aided Design
  3. High cut-off frequency in CE amplifier

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.

Reply to
honest
Loading thread data ...

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      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
              With Half My Brain Tied Behind My Back
              Still More Clever Than Mr.Prissy Pants
Reply to
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)

Reply to
Jamie

Jamie ha scritto:

This one. Found the issue. Thanks again.

Reply to
honest

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.