2 Replies Latest reply on Jun 25, 2010 3:43 AM by zbigniew.kuczbanski

    Precision Rectifier using PSoC® 3 AN59649 Not work correctly

    zbigniew.kuczbanski

      Hi,

         

       I am trying to use precision rectifier shown in AN59649 but in my opinion it not work correctly.

         

      Negative half of sine doesn't has gain -1.  Positive half sine gain is correct.

         

      I attach input (CH I, red) and output (CHII, blue) oscillogram.

         

      Hardware: PSoC3 CY8C3866LTI-030

         

      Pins: Input_sine - P0.0 (48), outp - P0.5(54), Reference - P0.1(49)

         

      External Input_sine pin connected to Reference pin via 10k resistor.

         

      All input and output have DC votage 2.5V (Vdda/2)

         

      Input signal sin, 200kHz, 3Vpp connected via 100nF capacitor.

         

      Power supply:

         

      Vdda=Vddio0=5V

         

      VddD=Vddio1=Vddio2=Vddio3=3.3V

         

      I check comparator output, it's correct.

         

       

         

      Question:

         

      How make correctly working precision rectifier?

         

       

         

      Best Regards,

         

        Zbigniew