Pspice problem..can someone help me...

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nadiahza

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Hye everybody..
I have problem with my Pspice...
i want to see capacitor charging when the switch off and switch on continuously...

in this post i attach my circuit..can anyone here help me to solved this problem...


thanks..
 

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I would suggest you make your SWITCH on and off voltages within you operating range such as 2V and 3V not 0V and 5V. Also, check the ON and OFF resistances of the switch - by default they are 1 ohm and 1M ohm which may not be what you want.

Also, I am not sure what you are expecting. You have no discharge path so the capacitor will charge up to 5V and stay there.

Keith
 



how to make the switch on off..can you give me an example of circuit how to switch off and on... i just want to see the rise of voltage when in discharge..acctually i want to simulate the circuit below..but i can not simulate it..
 

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U put transistor as switch and simply on and off the transistor by controlling the base through PWM signal
 

To duplicate that you need two switches in order to create a changeover switch. Set the two switched with opposite threshold voltages so one is on when the other is off. Alternatively you could use two different clocks, which would be necessary if you wanted to ensure they didn't overlap.

Keith
 

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  • EDA234 switched capacitor S-H.pdf
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in the pdf what type of switch are you using???
 

The same type of switch that you used, I think. One has the parameters "RON=1 ROFF=1Meg VON=3 VOFF=2", the other "RON=1 ROFF=1Meg VON=2 VOFF=3" so that one is ON when the other is OFF.

Keith
 

thanks keith...can you check my circuit..simulate already..i still cannot get the graph as yours.. i want to follow your circuit first..

- - - Updated - - -

here is the circuit..
 

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Your circuit is incorrect. The switch needs to connect between the input (1k resistor) and and the first capacitor. You have the switch connected to ground instead. Rotate your switch 90 degrees anticlockwise. The same applies to your second switch.

Keith
 
The switch has 4 connections. Two are for the control signal and two are for the "switch" itself. You need to connect the switch between the input and the output - R1 and C1 in your circuit. However, you have connected the switch between C1 and ground. At the moment you have connected the input signal from R1 to the control signal input, not the switch.

Think of it as a relay. The control signal is the relay coil, the switch is the relay contacts. You have the coil between the input and the control signal V2. The coil needs to go between the control signal and ground.

Keith
 
Yes. I used a sine so you can better see what the circuit does. With a DC voltage the capacitors will reach equilibrium and stay there.

Keith
 

But when 1 used dc...the i cannot see the charging of the capacitor...
 

What do you see? A fixed voltage the same as the DC input voltage? That is what I would expect. With no discharge path for the capacitors, once they are charged they stay charged. The "leakage" resistance through the switches will be enough for the simulator to decide that the initial equilibrium state ("DC operating point") is with the capacitors charged. You could "skip the DC operating point" - SKIPBP I think Pspice calls it.

Keith
 

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