How to Design Pulse Generator > 1Mhz?

Here you go....

I hav desined it before only mut iam getting on millisec range abut i want the timeperiod in micro seconds(i.e in MHz frequency...)

The circuit and principle suggested by RDGRNR is fine, just use fast enough parts to do the job. I recommend the TLV3501 (link), with its 4.5ns response. It also has a 30-ohm rail-rail output, which simplifies the circuit. For single-supply operation you can add an extra resistor, as shown in part of fig 7.1 from AoE 3rd edition (right). Just choose R and C small enough for the frequency you want, e.g. 100pF and 909 ohms for 5MHz. I'd drop the values of the other resistors by 5 to 10x.

One other simple point, Ejaz484, if you want a true square wave, with 50% duty cycle, the standard approach is to make 2 f with your oscillator, and use a divider flip flop to get your perfect square wave.

Sir can u also say why we need to 3.3eV energy to exicite an electron from valancy band to conduction band when it's bandgap energy is 1.1eV

Thanks sir for ur advices and circuits....

Sir can u plz explain how this circuit works by explaing significance of each and every component in the circuit please....?

you have to design pulse generator with the help of 555 timer ic and not with the help of op-amp because at this the effect of slew rate is coming which distort the square wave.you can simply use 555 timer as a schmitt trigger.

sajal, you haven't followed up for us on your question, "how to generate high voltage impulses with the help of electronic circuit", in the High Voltage Pulses thread.