Ring oscillator with 5 Schmitt-Trigger in a loop

[March2015]

Hey everyone. 

I need your help. 

I try to simulate following circuit consisting of 5 74HCT14 Schmitt-Triggers, that sould generate a square waveform. 

I am supposed to determine the fequency of the circuit and the duty cycle with the specifications from the datasheet of the 74HCT14 IC, but I do not understand how to do it. 

Further thing is, that the Tperiod goes from 50% of VDD of the first pitch to the second pitch on VDD/2.

I attached the circuit and my datasheet. 

I would be really tankful. 

74HC_HCT14_CNV_2.pdf

project.docx

[JColvin]

Hi @March2015,

Unfortunately, this looks like a homework assignment so none of the Digilent staff will be able to help you directly. I would recommend taking a look at this site that shows what sort of information you would need to get from the datasheet, which will be in a section with a title similar to "Electrical Characteristics" or "DC Characteristics".

Thanks,
JColvin

[hamster]

I have actually done this, and the speed only partially depends on the device parameters, the biggest being propergation delay.

Moving from a breadboard to hard-wired made dramatic changes in frequency (20%+) due to inductance and capacitance. Extra decoupling (which enhanced switching speed) also changed things. 

Supply voltage also made a big difference too.