Procedure

• The common-mode gain can be obtained directly with Circuit P9.2. This is accomplished with the VI, CBGain.vi. The squarewave input signal is applied with Chan1_out.
  
  

  

• Open CMGain.vi and set in the resistor values. Set Vs to a larger value than that used in Gain.vi, to compensate for lower gain. Run the VI to verify that the circuit is functioning properly. Expect the gain to be about unity, based on the design R_S = R_D/2. (Ideal common-mode gain is zero.)
  
  
• Open and run AvgCMGain.vi. Obtain a data file consisting of drain currents, V_SG, gains, and V_SD.
  
  
• Use SimAvgGain.vi to obtain a data file from data saved in AvgCMGain.vi. Copy and paste the graph data and the drain currents, V_SG and V_SD. Gains will be averaged from the graph data.