I'm a new user to ADS (Advanced System design). I'm trying to design a discrete Colpitt oscillator at 100 MHz in ADS. Here's my schematic: enter image description here

Now I wanna check if my circuit works properly. I watched and read some tutorial but it seems like a lot of new stuff to me. Can anyone help me to solve the problem?

  • 1
    \$\begingroup\$ your circuit won't work! place the inductor between collector and Vcc \$\endgroup\$ – Hamid R. Tanhaei Jun 20 '20 at 3:23
  • \$\begingroup\$ Yes you’re right it’s a big mistake. Thank you! \$\endgroup\$ – Henry Nguyen Jun 20 '20 at 21:52
  • \$\begingroup\$ By the way do you know how to use ADS? I’m wondering which type of simulation I should use? \$\endgroup\$ – Henry Nguyen Jun 20 '20 at 21:53

Problems in coloured boxes: -

enter image description here

  • \$\color{red}{RED}\$ box - no joining junction at cross over point hence transistor gets no bias
  • \$\color{blue}{BLUE}\$ box - inductor passes DC freely and hence connects collector to ground
  • \$\color{purple}{PURPLE}\$ box lower - Move C4 into vacant space in upper purple box and replace C4 with a short
  • \$\color{purple}{PURPLE}\$ box upper - Move C4 into that position
  • \$\begingroup\$ thank you! By the way, do you know how to use ADS? Which type of simulation should I use? \$\endgroup\$ – Henry Nguyen Jun 20 '20 at 21:49
  • \$\begingroup\$ Sorry I don’t know how to use it. I use micro cap 12. Did the fix proposals work? BTW if you are looking for a very good sim with tons of library parts, micro cap is now free (as in free beer and just as tasty). Highly recommended. \$\endgroup\$ – Andy aka Jun 20 '20 at 21:56
  • \$\begingroup\$ yes it helped. Actually I referenced this 100 MHz CB Colpitt Oscillator from the book Discrete oscillator design, Linear, Nonlinear, Transient and Noise Domains by Randall Rhea. Here's the schematic in the book drive.google.com/file/d/1N_f_R-uc-O8s287DE5zs4xJFunk1mlHi/… I don't understand the meaning of CP1, port 1 and port 2. I tried to edit the circuit and made the above mistake. Have you got any idea what those things mean? \$\endgroup\$ – Henry Nguyen Jun 20 '20 at 22:35
  • \$\begingroup\$ No, I have no idea but I wouldn’t worry. \$\endgroup\$ – Andy aka Jun 20 '20 at 23:36
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    \$\begingroup\$ @HenryNguyen I think you should raise this as a new question because others will likely want to contribute. Firstly though, go through a few questions using the search bar above to see if anyone has already answered this. \$\endgroup\$ – Andy aka Jun 21 '20 at 14:29

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