how to analysis this voltage ragulator schematic in qspice?

Voltage Regulator mode series

Voltage Regulator mode shunt

how to analysis this voltage ragulator schematic in qspice?

Voltage Regulator mode series

Voltage Regulator mode shunt

Let’s try to draw the schematic first, then you can learn the circuit’s works.

- Mac

If you have device part number and resistance value, you can search for corresponding device model to build a schematic for simulation.

Here is an example, where BJT and Zener are just basic textbook model.

- BJT is modeled with .model NPNi NPN BF=200 NF=.87, where BF is current gain Ic/Ib, and NF affect forward voltage drop between VBE, which normally ~0.7V in textbook calculation (this NF value give a simulated VBE ~ 0.7V drop in this circuit)
- Zener is modeled with behavorial diode model, with Zener drop (Vz) = Vrev = 5.1V

This demo schematic simulates effect of V(OUT) under supply voltage change or load change.

BJT-Zener-Voltage-Regulator.qsch (7.4 KB)

**Load Change**

**Supply Voltage Change**

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how if using op-amp

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thank you for your help. have a nice day

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