Self-Oscillation Schmitt Trigger

[OsmanH]

I have a question about self-oscillation schmitt trigger frequency? Can I get 10 MHz square wave from self-oscillation schmitt trigger. I build up schematic that is given below. Also, I must use LM158. Anyone can give me an idea if it is possible to get?

 

[FvM]

I must use LM158. Anyone can give me an idea if it is possible to get?

You got a clear answer in your previous thread. Particularly, notice the LM158 unity gain bandwidth of 1 MHz. As a simple conclusion, the part is simply useless to build an oscillator for MHz frequencies. Because the oscillator circuit needs certain gain, the maximum frequency is in a 100 kHz range. I didn't feel a need yet to find out exactly.

I guess this is an academic project. I hardly can't imagine, that you got an assignment that's impossible by principle.

 

[goldsmith]

Hey Gentleman
Hi
If you want 100MHZ frequency with op amp you should select high frequency op amp( as FvM said , with this op amp you cant) but i suggest you search in analog device chip s . 6 month ago i find an op amp that called video op amp , from analog device company(its frequency was 400MHZ)(4vpp) . and its price was good. i think you will can obtain your purpose with this op amp. mean while i think with this arrangement it is hard to obtain 100MHZ.
Goldsmith

 

[OsmanH]

I want to get 10 MHz not 100 again it isnt possible?

 

[FvM]

As I asked in your previous thread: Which high speed OPs are available to you? You'll need at least 50 MHz bandwidth (GBW), better 100 MHz.

Other than for the integrator stages involved in your previous thread, the present circuit can also work with a fast comparator, which can be imagined as an uncompensated OP.

The most simple way to build a schmitt-trigger oscillator is to use a CMOS 74HC14 or other fast inverting schmitt trigger logic IC.