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different current through two series resistors

Rezaee

As shown in the picture, the current through two series resistors are different !!!

What is the problem? How I can solve this?

Thank you in advance

 

 

 

Parents
  • Andrew Beckett

    I just tried it with a simple circuit and got sensible results (even without tightening tolerances). I still can't see why you care about fA currents, but if this is a problem for you I suggest you contact Cadence Customer Support with the design data so that an Application Engineer can have a look. What you've shown isn't enough to understand what the problem (if any) is. Here's what I did:

    // spectre netlist to try to show small resistors
    r1 (n2 n1) resistor r=0.05
    r2 (n1 0) resistor r=3.2
    v1 (n2 0) vsource dc=7.5f

    dc dc
    oppoint info what=oppoint where=screen

    And here's what it output:

     

    Instance: r1
    Model: resistor
    Primitive: resistor
              1 : V(n2) = 7.5 fV
              2 : V(n1) = 7.38462 fV
              v = 115.385 aV
              i = 2.30769 fA
            res = 50 mOhm
            pwr = 266.272e-33 W

    Instance: r2
    Model: resistor
    Primitive: resistor
              1 : V(n1) = 7.38462 fV
              2 : val(0) = 0
              v = 7.38462 fV
              i = 2.30769 fA
            res = 3.2 Ohm
            pwr = 17.0414e-30 W

     

     

Reply
  • Andrew Beckett

    I just tried it with a simple circuit and got sensible results (even without tightening tolerances). I still can't see why you care about fA currents, but if this is a problem for you I suggest you contact Cadence Customer Support with the design data so that an Application Engineer can have a look. What you've shown isn't enough to understand what the problem (if any) is. Here's what I did:

    // spectre netlist to try to show small resistors
    r1 (n2 n1) resistor r=0.05
    r2 (n1 0) resistor r=3.2
    v1 (n2 0) vsource dc=7.5f

    dc dc
    oppoint info what=oppoint where=screen

    And here's what it output:

     

    Instance: r1
    Model: resistor
    Primitive: resistor
              1 : V(n2) = 7.5 fV
              2 : V(n1) = 7.38462 fV
              v = 115.385 aV
              i = 2.30769 fA
            res = 50 mOhm
            pwr = 266.272e-33 W

    Instance: r2
    Model: resistor
    Primitive: resistor
              1 : V(n1) = 7.38462 fV
              2 : val(0) = 0
              v = 7.38462 fV
              i = 2.30769 fA
            res = 3.2 Ohm
            pwr = 17.0414e-30 W

     

     

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