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Hi folks, currently I'm designing a 7-bit DAC with R2R. I have to use Menthor Graphic ELDO to draw the schematic and layout.
Firstly, I have problem with the switches on R2R ckt. I have these 3 ckts (images enclosed). I'm not sure which is the correct 1. If all these ckts are wrong, anyone minds to draw a correct 1 for me?
And for the Op Amp part, I did it first with the current sources. I think it worked. But after I draw the real Op Amp (with changes and added CMOS transistors), it fails (2nd Image). I know that the all the transistors must be in saturation to "ON". What is the function and value of Rbias? What is the current across all the ckt? Shoud I adjust the current to the previous value like in Image1? What is the correct output V?
Or anyone has a completed full schematic is welcome to send to me!
I need to come out with something in two days. Hope someone will help in this! Thank you very much!
Firstly, I have problem with the switches on R2R ckt. I have these 3 ckts (images enclosed). I'm not sure which is the correct 1. If all these ckts are wrong, anyone minds to draw a correct 1 for me?
And for the Op Amp part, I did it first with the current sources. I think it worked. But after I draw the real Op Amp (with changes and added CMOS transistors), it fails (2nd Image). I know that the all the transistors must be in saturation to "ON". What is the function and value of Rbias? What is the current across all the ckt? Shoud I adjust the current to the previous value like in Image1? What is the correct output V?
Or anyone has a completed full schematic is welcome to send to me!
I need to come out with something in two days. Hope someone will help in this! Thank you very much!