Question

once simulated can tou explain what the diodes are doing ... please explain good thank you

Problem 1: Voltage Limiting 1.1. Simulate the following simple resistor-diode circuit (shown on the left in Figure 1) R1 V out V1 ZD1 VOFF 0 VAMPL 3V FREQ 1KHZ 0.7 D1N4148 Figure Let V(in) be a 1KHZ VSIN with an amplitude of 3V. RI is 1KO. Lowest node voltage is ground. (1.1a) Set up PSPICE Transient and plot both V(in) and V(out) on the same scale. See that the upper part of V(out) is clipped at around 0.7V. Run time = 3ms; Time-step = 10us (1.1bb) Increase the amplitude of V(in) to 8V, and plot both V(in) and V(out) on the same scale and see that V(out) remains clipped at around 0.7V (1.c) Finally reduced the amplitude of V(in) to 100mV, and plot both V(in) and V(out) on the same scale and see that V(out)-V (in) (no clipping occurs) Explanation: As long as V(in) is below the cut-in voltage of the diode (around 0.5V), the diode is OFF. Therefore V(out)-V(in). When the input voltage is such that the diode begins to conduct, V(out) becomes equal to a diode's forward voltage 1.2 In Figure 2, if we rotate the diode 180°, diode will turn ON when V(in) falls below -0.5V. We thus obtain a limiter that lower limits at -0.7v. Repeat (1.1a, 1.1b, and 1.1e) for Figure 2: Run time 3ms; Time-step= 10us. AV M R1 VOFF 0 VAMPL V FREQ TH 01N4148 0.7 Figure 2

Answer 1

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