I need to setup some simulations on QUCS for the RF circuit below:

enter image description here

Pin1 is IC's positive port and Pin2 is IC's negative port.

My initial goal is to investigate the circuit behavior on different frequencies and different lumped components values. After that, I want to calculate the impedance matching and best pcb transmission line.

I saw many QUCS examples, but all of those is using a single power source.

So, how can I setup a differential signal source on QUCS?

pointing to an example would be very helpful !


1 Answer 1


Well the first two letters of qusc stand for "quite universal" so, if it's as good as its name then use two sources that generate antiphase signals. Or use one source and a voltage controlled voltage source (inverting configuration) to generate the other.

  • 1
    \$\begingroup\$ This should work, but if you plan on using the s parameter excitation source you will have to combine the responses of both ports with some equation. You also need to terminate the reflected common mode signals. Another approach which I used in ADS is to use an ideal 4 port balun. QUCS doesn't have such a device built in AFAIK but you can probably model one with a transformer or an equation based model. \$\endgroup\$
    – Mike
    Sep 1, 2018 at 6:46

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