high frequeency(1mhz) rectangle wave with 30% duty cycle

[mtijijoy]

i need to generate an asymmetrical rectangle wave of 30% duty cycle ..freq between 500khz to 1 mhz

 

[rohitkhanna]

You can do this simply by using an 555 chip (or variant).
Like this

https://www.falstad.com/circuit/#$+...6+9.353610478917778+9.765625E-55+0+-1+output


Even more simply using a schmitt NOT gate, a cap, 2 diodes, 2 resistors/ or 1 potentiometer.
Connect the same way as in 555, except that the resistor/ cap juntion goes to input, and diodes go to output.

Just vary the resistors/ cap values to get what you need.

 

[crutschow]

Does the duty-cycle need to be constant as the frequency is varied? If so then one way is to use a higher frequency pulse generator (astable) with a counter and gates to generate the desired frequency and duty-cycle. For example, a divide-by-three counter could be used to generate a 33% duty-cycle signal. If you need exactly 30% then you would need to use a higher order counter such as a divide by 10.

P.S. I assume you mean 1MHz, not 1mhz (.001Hz) :wink: