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Subject: dac

Date: 10/04/03 at 12:54 PM
Posted by: jason
E-mail: jason_class[AT55]yahoo.com (replace [AT55] with @ to reply)
Message Posted:

Hi Russ and Mike

I need your help on DAC again

In the page
http://www.geocities.com/jason_class/dac.gif

See the differential pairs and Q3 and Q4, Q3 and Q4 as cascode current source. It is said that the when both nput at differential pair is high, Vout is shorted to ground. Can help to explain why this happen?

Then when both the output is low, voltage at drain Q3 is pull low. WHy is it so?

It is said the solution is to vias the gate for Q2 at dc bias. How does this solve the problem?
May i know why the drain of Q1 must connect to GND?


Please guide me .
Thank you

rgds
Jason


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      Re: dac Russ Kincaid   Posted at: 10/04/03 (0)


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