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Diode application • Rectifier circuit – – – – • • • • Half-wave Full-wave Full-wave bridge With capacitor Clipper Clamper Zener diode and applications Voltage multiplication Half-wave rectifier • Vi(t)>0 => D on • Vi(t)<0 => D off Full-wave rectifier • Vi>0 => D1 on, D2 off • Vi<0 => D1 off, D2 on Full-wave bridge rectifier • Vi>0 => D2, D4 on; D1, D3 off • Vi<0 => D2, D4 off; D1, D3 on Full-wave rectifier with capacitor • Vi>0 => D1 on, D2 off • Vi<0 => D1 off, D2 on Clipper • Parallel or serial • Serial: – Vi>V => Vi – V > 0 => D on => Vo=Vi-V – Vi Vi – V < 0 => D off => Vo=0 Clipper • Parallel with additional source – Vi>4V => D off => Vo = Vi – Vi<4V => D on => Vo = 4V Clamper • Shift the level of DC • Must have a capacitor and a diode in the circuit Zener diode • Forward bias: like normal diode • Reverse bias: – Work at the breakdown zone – Voltage = const (see the plot) • Application: always reverse bias – Reference voltage Zener diode simple application • IR=(Vin-Vz)/R; IL=Vz/RL; Pz=Iz*Vz RL >RLmin RLmax=Vz/(IR-Izmax) RLmin=RVz/(Vi-Vz) • Vin varies, RL = const: Vimax > Vi > Vmin Vimax=RIRmax+Vz Vimin = Vz(R+RL)/RL Double voltage • Positive phase: D1 on, D2 off, VC1=Vm • Nagative phase: D1 off, D2 on, VC2=Vm+VC1=2Vm Multiple voltage • Positive phase: D1 on, D2 off, VC1=Vm • Negative phase: D1 off, D2 on, VC2=Vm+VC1=2Vm Diode – effect of temperature Homework • Chapter 2: 1, 5, 6, 10, 11, 15, 21, 23, 24, 27, 30, 34, 37, 42, 47, 49, 52