Hex inverter oscillator

The delay is created by the alternate charging of capacitor Cl (through Rl) and the discharge of Cl (through R2). The output is a square wave 

The IsSpice simulation results are shown in Fig. 8.19. These results compare very well with the measured performance (Fig. 8.20). 

The circuit was also simulated in PSpice and Micro-Cap. The results of those simulations are shown in Figs. 8.21 and 8.22. In Fig. 8.22, interestingly, the Micro-Cap results showed an output frequency roughly twice that of PSpice or IsSpice. The reason for this is the Micro-Cap 

Advantages Low parts count, good drive capability 

Disadvantages Accuracy over life, temperature probably unpredictable 

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