how to connect adc to dac

Discussion in 'The Projects Forum' started by shiva kumar, Jul 6, 2011.

  1. shiva kumar

    Thread Starter Member

    Jun 27, 2008
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    Hi ,
    I am new to this forum,i need some suggestions regarding my project,,we are actually trying to build a pipelined adc using cadence tools,,,for that purpose we require flash adcs,we have designed a 4 bit flash adc,,,we were asked to build a a dac and connect our flash adc to this dac and check whether we are getting the original waveform,i have few queries regarding this,
    1)Can we directly connect the output of the flash adc to the dac??

    2) We are planning to use a resistive divider or capacitive divider dac,,as we all know,we need "switches" to connect the resistors either to reference voltage or the ground,what is the hardware equivalent for this "switch",can i use 2:1 multiplexers for this purpose??

    I am new to these electronic projects,some of my doubts might sound silly,,please excuse me.
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    This sounds like a homework or lab assignment given to you by a teacher/professor. Is it?
     
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    1) Probably you can make that connection, as you are connecting a digital output to a digital input. It may depend on the details of...

    2) the dac: with a R2R ladder you can drive each resistor directly with the logic output bits of the adc, though you may have to scale the output depending on what each bit weighs in volts (ie, the implicit units of the conversion). Keep in mind any digital noise on the digital lines will be coming out as analog noise.

    I'm not sure how a capacitive divider works (never used one) but I believe it would need some sort of analog transmissive gate as the switch element.
     
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  4. shiva kumar

    Thread Starter Member

    Jun 27, 2008
    11
    0
    Hi
    As i said earlier,i am new to these projects,,i am an engineering student,i am doing this project because i am interested in analog design,i was told that pipeline adc is one of the complicated circuits,i thought that designing this circuit will help me in the future,i approached my instructor at the college who suggested me to design flash adc first and check whether it is working ,it is not a home work,i really dont know whether adc can be connected to dac directly as it is my first time i am laying my hands on this adc stuff,
    I thought that i would get some help from this forum.
     
  5. shiva kumar

    Thread Starter Member

    Jun 27, 2008
    11
    0
    thanks a lot
     
  6. SgtWookie

    Expert

    Jul 17, 2007
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    I'm not trying to give you a hard time. It's all too frequent that students want us to do their homework for them, which only teaches such students to keep getting other people to do their work for them.

    Since we don't know what your flash ADC looks like, or which DAC you might use, it's difficult to tell whether or not you will have problems connecting them up.

    You'll at least need to wait long enough for the ADC output to stabilize before starting the DAC. If the input bits don't change at the same time, you'll wind up with glitches on the output that you will need to filter out.
     
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