Ring Oscillator with Delay

[firsttimedesigning]

i am designing a ring oscillator that will function as a clock generator. However, I would like it to have some delay at the begining. What I mean is that it will delay for 2 seconds, (during that time it will only produce a low voltage signal) and then, it goes to function as a normal clock generator.

the problem is, i dont know how to create such a delay...
any idea?

 

[renwl]

I think that maybe make the gain lower can get it.
however, maybe the ring oscillator will never oscillate again when the gain is not enough.

 

[catur_3414]

try this circuit.

adjust the delay with replace the R (50k) and C

 

[dhasmana]

Can use a RC circuit (high R less C) and sense the output voltage and generate a bypass signal which will bypass the RC once the level is reached.This will happen only during the startup.

Regards,
Jitendra Dhasmana.

 

[manish12]

it is simple one .

this is the best , what you can get !

 

[Sadegh.j]

use an a-stable, easy

 

[s_babayan]

dear friend you can use some inverters which can have a determined delay time. so you can use their delay time for the time you require. Hope it will be useful for you.

Samaneh

 

[lijianheng]

DLL? I'm not sure.

 

[northeast1]

i am designing a ring oscillator that will function as a clock generator. However, I would like it to have some delay at the begining. What I mean is that it will delay for 2 seconds, (during that time it will only produce a low voltage signal) and then, it goes to function as a normal clock generator.

the problem is, i dont know how to create such a delay...
any idea?

you can add a power down circuit in the circuit to control the delay

 

[kumarghz]

Dear designer,
you may try this circuit as I attached.
you see, the Cap will start to charge upon the circuit activated, however the cap takes time to charge from 0v to 5v (vcc) . At beginning the output of the schmitt trigger is '0' so the AND gate. as the cap charge from 0v and reached the Vth of the schmitt trigger the output of the schmitt trigger goes high and the output of AND gate copy the ring osc.
The delay established here is when the cap charge from 0v to Vth. you may vary the value of Cap & R to achieve desired delay.
Thanks. good luck.
-kumar

 

[sp]

haha so most people here is analog type (cap, gain, astable)... I'm a digital one so I would suggest that we use control logic to do the initial delay...

normally your ring oscillator will have a "enable" to start the ring loop, so perhaps you can use a counter to count till two second before you assert the "enable". this need to be done whenever you want to assert the "enable" for your ring oscillator...

hope this is useful

 

[hock]

if you post it in analog forum you will get analog replys only. please post your request in digital forum.
hock

 

[Asif2008]

dear u should study the david and pozar

 

[chip2000]

you could use a powe supply voltage supervisor ic like the tl7705 that will produce a programmable pulse when you connect the power. (it was design to give the reset signal) you will AND gate this signal with your clock
Alternatively you can use o CD4541 ic that will drive the AND gate that blocks the clock. the CD4541 has reset on power circuit and gives programmable delay...

 

[armixic]

2 second is too long for a on-chip delay. try to use some logic control sequence to power-up the ring.

 

[sudhakarj.tech]

Hi Asif2008,

Can you have the soft copy of DAVID & POZAR for analog ckt design, or can u send me the link corresponding to........or can u plz send it to me on

>>>>>>>>sudhakarj.tech@gmail.com<<<<<<<<<

 

[jecyhale]

Use an counter to count the dealy.

 

[butterfish]

You can use a RC delay, and divide it to 2S sqware wave.

 

[heng155]

You can use a much small & slower Ring Oscillator to set the timng.

 

[mady79]

If u got a clock in a system ,set counter and add a synchronous wait signal after the count is reached .hope this helps