circuit integrator for high frequency switching

Thread Starter

tira_othman

Joined Jul 23, 2008
6
hello everyone !!

i was doing research based on this topic, but i couldn't find anything that satisfy me. i am looking for an integrator circuit, which has the clock (BJT) to control the high frequency dc switching. basically, this is for power electronics project.

i supposed to do the input voltage feedforward pulse-width modulator for dc switching power converters. as for now, i need to find the integrator circuit which it can control the high frequency dc switching.

anyone can help me ?

thank u!
 

Thread Starter

tira_othman

Joined Jul 23, 2008
6
ok, i guess, everyone is not understand what am i saying .. so, this is the simulation picture, but i didnt get the sawtooth output as what my mission needs.
so, pls help me with this .. i need to get an output like circuit integrator3 picture, but i must use transistor like circuit integrator4 .. but i cant get an output like circuit integrator3 .. can anyone really help me with this ?
 

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SgtWookie

Joined Jul 17, 2007
22,226
The dark blue of the channel B trace is extremely difficult to see; it appears nearly black to me, and I can't make out the waveform very well.

Can you make it something brighter, or change the background of the O-scope to a more contrasting color?
 

Thread Starter

tira_othman

Joined Jul 23, 2008
6
this is the pictures for circuit integrator2 (int2) and circuit integrator3 (int3) .. i want circuit integrator3 to produce sawtooth waveform like the output from int2 .. :confused: the 1st picture is output from circuit integrator2, the second one is from the circuit integrator3 .. from the previous post, i mentioned about 3 and 4, im sorry, it was wrong, i meant 2 and 3 ..
 

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Last edited:

bertus

Joined Apr 5, 2008
21,950
Hello,

Could you have a problem with the bandwith? (the signal look rounded).
Your experiment is using 3 MHz, pretty close to the unity gain bandwith.
The LF356 has a unity gain bandwith of 5 MHz.
The LF357 has a unity gain bandwith of 20 Mhz.
The LF 357 has also a larger slewrate of 50 V/uS.

Greetings,
Bertus
 

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Thread Starter

tira_othman

Joined Jul 23, 2008
6
hello ..

the purple is the output .. is that correct for the sawtooth output ? this is only for positive part since transistor is connected. Does this graph makes any sense ?

i really2 need opinions here !! :confused::confused::confused:
 

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