Zener Diode

• In the case of zener diode the differential voltage & current in the zener region of the characteristic curve is given through

                                                                        ΔV = r_z. ΔI

            here r_z = incremental resistance of zener diode or inverse of the slope at operating point.

The approximately linear i-v chracteristic of zener diode recommend that the device may be modelled as indicated

• In practice, knee voltage & V_z0 are considered similar. From the model

                                                                         V_z =V_zo +r_z + I_z

                                                                        here I_z > I_zk

                                                                                & V_z > V_zo