The two-diode circuit shown in Fig. P18.49 can provide a crude approximation to a

Chapter 18, Problem 18.49

(choose chapter or problem)

The two-diode circuit shown in Fig. P18.49 can provide a crude approximation to a sine-wave output when driven by a triangular waveform. To obtain a good approximation, we select the peak of the triangular waveform, V, so that the slope of the desired sine wave at the zero crossings is equal to that of the triangular wave. Also, the value of R is selected so that when vI is at its peak, the output voltage is equal to the desired peak of the sine wave. If the diodes exhibit a voltage drop of 0.7 V at 1-mA current, changing at the rate of 0.1 V per decade, find the values of V and R that will yield an approximation to a sine waveform of 0.7-V peak amplitude. Then find the angles (where = 90 when vI is at its peak) at which the output of the circuit, in volts, is 0.7, 0.65, 0.6, 0.55, 0.5, 0.4, 0.3, 0.2, 0.1, and 0. Use the Figure P18.49 angle values obtained to determine the values of the exact sine wave (i.e., 0.7 sin ), and thus find the percentage error of this circuit as a sine shaper. Provide your results in tabular form.