Question

1. Draw the current-voltage characteristic of a Zener diode and show the forward and reverse biasing areas. Mark the "Zener voltage" value on the graph. Explain how the voltage on the Zener diode will vary when it is biased with a voltage higher than the Zener voltage. 2. Explain the operating principle of a full-wave bridge rectifier by clarifying which diodes becomes active during the positive and negative cycles of the input signal.

Answer 1

Zener diode: I (MA) -VBY 0,7V V Faword Bias → Reverse Bias • Vz where V2= Zener voltage. I like as always Operated under » Basically it is a pn junction diode with little increase in doping levels (I in los). & It is fabricated only wilt silicon When it is forward biased, it operates ordinary diode, > It is reverse bias with voltage greeter Ito an breakdown voltage. When voltage (reverse voltage under Yeverse biased condition) applied i's higher than the breakdown Vz then Zener diode conduction & Voltage across it is Constant it is equal to 'V2. operation of full wave bridge rectifiet: Vint voltage (VBY) (07) starts Di Vo toa N 20 wt Vin AC 2 D2 le Dj Ri 不一 늘 VE 21. wt During the half cycle of supply: Di Da •current direction + 1 Vin By vo Dz During diodes diodes tuc half-cycle of supply, diodes Di&D, conduct wherbas D3 & Dq arre yev. biased 8 do not cmduct. The conducting in series with 'Ri, so the load current flows through Re: are

During -ve half cycle of supply: Di current direction 个 04 Vin ele + RL vo + D. +P3 During rue half cycle of supply, diodes Dz & Dq are where as diodes D, & D2 are forward reu. biesed biased and conduct 2 doesn't conduct diodes D₃ &.De are in series with they 'RE : the 'Ri in same direction as in previous current flow through half-cycle. Thus unidirectional a bidérectional wave is converted to Wave