Op-amp, transconductance amplifier and comparator


How to make/simulate a simple operational amplifier, transconductance amplifier, and comparator in QSPICE?

Assume you are looking for textbook type of simulation

In this Github : KSKelvin-Github/Qspice: Qspice technique, symbols and examples

  • Folder : Symbol - Ideal Opamp and Ideal Comparator symbol and pdf explanation
  • Folder : Guideline - Qspice - Device Reference Guide by KSKelvin.pdf
    Goto section Ã-Device, explain detail about Multiplying Gm Amplifier MULTGMAMP
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Hi Kelvin, I am wondering if this ideal operational amplifier can be transformed into an ideal transconductance amplifier in order to be used as transconductance amplifier:

Is it possible this?

Qspice has operational transconductance amplifier (OTA), which is Ã-Device <MULTGMAMP>. Both Qspice and LTspice have OTA, but they are defined differently in how output current is drawn. Qspice OTA current return to Vdd/Vss, LTspice OTA current return to REF.

Get my latest Device Reference Guide or goto Qspice HELP for more information.
(I made an update for OTA last week, but I am uncertain something about Rout and may be information in that section may change in future)

But how to spot the differences between them (op-amp vs transconductance amplifier) in terms of transient and ac analysis? A comparison between them…this is the idea