View attachment 195853
View attachment 195854

Hi
The non-linearity started slightly at the Opamp output as seen in the first chart, but was magnified in the Emitter of the BJT as seen in the subsequent chart

Hi,

The first thing to do then is find the cause of the non linearity coming OUT of the op amp. Note i said "OUT" because we dont know what is going "IN". If the signal going in is not linear to start with it will never cause a linear output.
Now i wonder if the signal at the input cap is linear.

 

Hi,

The first thing to do then is find the cause of the non linearity coming OUT of the op amp. Note i said "OUT" because we dont know what is going "IN". If the signal going in is not linear to start with it will never cause a linear output.
Now i wonder if the signal at the input cap is linear.

Hi
Thank you for the insight, i have also changed the Opamp to a AD8656 which is more rail to rail. But i will also check the filtered input to see if this is the source of the problem.
Regards.

 

Hi all, the following os the results after implementing a rail to rail opamp. The only challenge is the last voltage (99%) that is yielding a lower output than expected. Is there a way i can split the opamp gain resistor trough a Demultiplexor so that it selects a particular resistor when the PWM is above 90%??

PWM%	DC Out	Required
9.76​	596​	588​
21.5​	1315​	1294​
25.5​	1562​	1594​
36.33​	2218​	2188​
47.26​	2887​	2847​
99.6​	5314.5​	5800​

 

wont setting to "1n" change my frequency operation from the required 40kHz?

Tperiod sets the frequency. Trise will not effect the frequency.
Toff = Tperiod -(Ton+Trise+Tfall)
10.5= 25n -(12.5+1+1)

 

Tperiod sets the frequency. Trise will not effect the frequency.
Toff = Tperiod -(Ton+Trise+Tfall)
10.5= 25n -(12.5+1+1)

Thanks i understand now.. By the way i hope you mean Micro not Nano, because Nano results in to a frequency of 40 MHz. Let me try putting the rise time and fall time as you advised .
Regards

 

Hey All
I altered circuit as advised and also added a feedback at the Emitter of the BJT. However, the DC output is not very linear, is there a way i can put the Feedback at the Output so that it can control the Opamp? Could one connect through an AZ431 Reference IC or how exactly to connect it?View attachment 195665

Hello All, Could Someone please help me convert the half-bridge inverter part of this circuit to full-bridge ?? So that i don't have to use a center-tapped transformer. Hence the inverter will have 4 switches instead of 2... I am not sure how to wire it up correctly.. thanks.

 

Hello All, Could Someone please help me convert the half-bridge inverter part of this circuit to full-bridge ?? So that i don't have to use a center-tapped transformer. Hence the inverter will have 4 switches instead of 2... I am not sure how to wire it up correctly.. thanks.