EZDAC I/V Simulation

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I am posting a circuit simulation that I did some time ago when I was designing the I/V stage for the e_zdac. This was done using TINA-TI, a graphical SPICE simulator which you can download for free from the TI website. The file is called ezdacIV.TSC (it's also on the e_zdac Builders Group website). I'm definitely not an expert with it, but I think I figured out the basics, anyway. Assume the model is for the right channel (but obviously the left channel is the same). I've set the I/V resistors (R29,R30) to 25R, and the feedback resistors (33,34) to 1.5K. The op amp input resistors (R31,R32) are 100R. The current is set to +/-3.9mA, which gives (I think) an amplitude equal to 7.8 mA, so simulating the PCM1794. The frequency is set to 1000Hz. For this set of parameters, I get an output from OPA134 (probably doesn't matter much what op amp is put in here, right?) of 2.34V. I'm not sure if that represents the peak or the RMS. Anyway, Leo K. measured the output of his DAC for this set of parameters and found the output to be very close to the sim. So, if you want to muck around with the values of various components, the simulation is a good place to start. Have fun, kiddies!

EZ DIY Audio Designs

Originally posted on 04/11/07.