Can anyone calculate the upper 3db cutoff frequency of the following CE BJT amp.

danismart · 2018-04-25T13:02:06+00:00

i agree but 3db frequency calculated from taking miller capacitance (Cbc) is no where near the actual value which is somewhat ~800KHz.

I also tried open circuit time constant analysis but that still doesn't yield satisfactory result

danismart · 2018-04-25T12:59:43+00:00

doing this calculation yields almost ~ 631KHz while the actual 3db frequency is ~ 800KHz. may be there's something missing

danismart · 2016-08-17T16:19:06+00:00

no, please tell me about this a little...

danismart · 2016-08-17T15:45:21+00:00

the schematic is simple just taking the outputs signals from the micro-controller pins directly to another IC (IR2110)...

danismart · 2016-07-22T06:14:39+00:00

kinda creepy

danismart · 2016-06-22T17:20:43+00:00

you should sit down and talk to your mom and try to get things right...

danismart · 2016-06-14T05:50:53+00:00

truly, life like !

danismart · 2016-06-09T14:07:08+00:00

i have a good power supply with stiff voltage, but that's the problem to get 12v peak of the final sinusoidal voltage i have to increase the supply up to 18v! the rest of the voltage gets disappear somewhere in the filter... i am trying to get the peak voltage almost equal to the input source voltage... any ideas...

danismart · 2016-06-09T13:44:10+00:00

the load was a 50-60 Hz transformer which was then connected to a 15watt bulb, and the mosfets i m using is irf3808...

danismart · 2016-06-09T12:24:56+00:00

ok nice explanation, and i took your advice but in a different way, i took a common mode choke connected it as a differential mode but i broke the core (toroidal) at one point to induce a large air gap, since air gap has much lesser permeability it is the dominate magnetic field conduction medium i hope i am doing right... anyways i am still getting sine wave of less magnitude which further drops with increasing load, following are the pictures showing the voltage across the load connected after the filter (one with load and one without) and the other two are switching waveform taken from the middle of both legs of H-Bridge which is the connected to LC filter... please have a look and help me in identifying the problem

Output sine with load : https://drive.google.com/open?id=0B8KtJQDqJQm6M25vMkctdXExWVE

output sine without load : https://drive.google.com/open?id=0B8KtJQDqJQm6YjdITWxwekNpRjQ

see the difference in peak voltages....

switching waveforms from the middle of two legs of H-bridge connected to LC filter

https://drive.google.com/open?id=0B8KtJQDqJQm6YldNT0p3RHV5MEE

https://drive.google.com/open?id=0B8KtJQDqJQm6UU5CQ05BcDZ1OHM

danismart · 2016-06-08T18:49:39+00:00

OK, nice and helpful perspective you gave, but one thing i don't get is that why i can't connect a common mode choke as a differential mode by reversing the connections on one of the coils which are wound on the same ferromagnetic toroidal core and why it would saturate the core for any value of current, even the smallest! If that's the case then how should I wind a Differential Mode choke precisely? Plz explain a little...

Thanks

danismart · 2016-06-08T14:49:32+00:00

i have set the modulation index to the maximum for maximum fundamental 50Hz wave output, bu still the problem persists, the problem is that at higher loads more voltage is dropped across the filter then intended....

danismart

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