Components

Compute C_b for Circuit C3. (Use ProjectC1.mcd.) It will be more than adequate for Circuit C2.

SubVIs

SetVSD.vi (Set Bias)

FG_10.vi (Function Generator)

FG_12.vi (Function Generator)

SR_10.vi (Send – Receive Function)

SR_12.vi (Send – Receive Function)

Oscilloscope_10.vi (Chan0_in)

Oscilloscope_12.vi (Chan2_in)

LabVIEW Computations

Procedure

• Connect the additional components in Circuit C2, R_s, and C_b. Connect Chan2_in for reading for reading the base signal voltage.
  
  
• GainSub.vi sends out bias and signal voltage (Chan1_out). (The signal is superimposed on the bias; the bias is modulated with signal.) Chan0_in reads the response (output of amplifier). The VI then resends the input signal (Chan1_out) and reads the response at the base (Chan2_in). These results are displayed in the two graphs. The ac peak values are used to calculate the gain. The VI also computes and displays rπ, βDC, and βac.

  

  
  
  
• Open GainSub.vi. Set the Digital Controls for collector resistor, R_C, base resistor, RB, and Rs. Rs is used to compute the signal current through Rs. Set Frequency at between 10 and 1000 Hz. Set VBB for 0.1 mA as determined with SetVCE.vi. VCC(init) must be less than or equal to 2 V. Default the Front Panel to hold these values for when GainSub.vi is used as a subVI.
  
  
• Ratio VBB/Vs is set at 5. The VI uses this to set V_s = V_BB/5, producing, roughly, I_B/I_b = 5. This results from I_B = (V_BB – V_BE)/R_B and I_b = V_s/R_B. This current ratio provides for operation in the linear mode.
  
  
• Run GainSub.vi and verify I_C ≈ 0.1mA. Verify that signals for V_be = V_in and V_ce = V_o appear to be undistorted (maintain sine-wave integrity). Assess all numbers in the Digital Indicators. At the low current of the measurement, Gain should be very close to g_m·RC. Default and save the Front Panel to save settings for the next VI.