hi every one

can any tell me that how can i convert the frequency into the voltage by using the digital gates only.

Frequency into voltage using digital gates only?

Digital gates don't produce a proportional voltage output, so the question seems a bit flawed.

With a reference clock of some form, you can use counters to determine number of cycles for a defined period of time. That gets you a number that indicates frequency.

With that, you can create a DAC structure that outputs a proportional voltage. A PWM DAC can be made with logic gates mostly, and a LPF.