Problem

8.3 We have discussed the features of CMOS Schmitttrigger. It has been pointed out a usefu...

8.3 We have discussed the features of CMOS Schmitttrigger. It has been pointed out a useful application lies in the receiver circuit design to filter out noises. However, in terms of speed performance it delays the switching activity. In view of speed alone, it would be useful to reverse the switching directions. In particular, we want to have the negative going (high to low transition) edge to occur at an input voltage smaller than the typical inverter's saturation voltage and also the positive going (low to high transition) edge to occur at an input voltage larger than the inverter's saturation voltage. Complete the circuit connection in Fig. P8.3 to realize such a circuit block for the assembly of the following components. Justify your answer by using SPICE circuit analysis. You can make some approximation technique to simulate the circuit. For instance, the different VTC curves can be simulated by using inverters of different p ratios. To be more specific, for larger saturation voltage, you can use an inverter with strong pull-up transistor, and for smaller saturation voltage use an inverter with strong pull-down transistor.