walid Posted October 24, 2005 Report Share Posted October 24, 2005 I write the following prog to simulate the circuit shown in Fig.C-E below:common E Amp freq responseVCC 7 0 DC 12VS 1 0 AC 1Q1 4 3 5 Q_2N2222A_NRS 1 2 1KC1 2 3 2uFR1 3 0 10KR2 7 3 30KRC 7 4 4.3KRE 5 0 1.3KC3 5 0 10uFC2 4 6 0.1uFR3 6 0 100K.MODEL Q_2N2222A_N NPN( IS=11.9F NF=1 NR=1 RE=649M RC=1 + RB=10 VAF=83.5 VAR=41.7 ISE=350F ISC=350F + NE=1.58 NC=1.58 BF=204 BR=5 IKF=149M + IKR=149M CJC=13.1P CJE=30P VJC=2.87 VJE=678M + MJC=330M MJE=330M TF=531P TR=69N EG=1.11 + KF=0 AF=1 ).op.endThe .op command results are:NAME Q1 MODEL Q_2N2222A_N IB 1.25E-05 IC 1.71E-03 VBE 6.66E-01 VBC -1.74E+00 VCE 2.40E+00 BETADC 1.37E+02 GM 6.53E-02 RPI 2.35E+03 RX 1.00E+01 RO 4.90E+04 CBE 8.44E-11 CBC 1.12E-11 CJS 0.00E+00 BETAAC 1.54E+02 CBX 0.00E+00 FT 1.09E+08 And I need to discuss some of these results with you:(1) How far or close these results to the real life, can i depend on it initially?(2) RPI is the i/p impedance looking into the base of Q1, so, the total i/p impedance is: R1//R2//RPI = 1.8K ohm. so we can look at the i/p portion of the circuit as: Vs connected in series with Rs then to C1 then connected inseries to that 1.8k. if we look at Vs as a MIC and Rs as the impedance of the MIC and C1&Rtot as a high pass filter, is the value of C1 suitable and why?(3) What exactly these parameters mean: GM, RX, RO, CJS, CBX.(4) FT is (as I remember) is the freq at which the gain =1, that is at this freq there is no amplification, Is this OK?(5) In the MODEL Q_2N2222A_N, BF = 204 is this the upper value that this Q can reach?(6) In the MODEL Q_2N2222A_N, what these mean: NF=1 NR=1 NE=1.58 NC=1.58 IKF=149M IKR=149M VJC=2.87 VJE=678M MJC=330M MJE=330M TF=531P TR=69N EG=1.11 KF=0 AF=1 thats allthank you in advancewalid Quote Link to comment Share on other sites More sharing options...

audioguru Posted January 14, 2006 Report Share Posted January 14, 2006 (1) How far or close these results to the real life, can i depend on it initially?Hi Walid,Doesn't your sim program have built-in spec's for common transistors? A typo can mess it up.The sim program works with "typical" spec's. The actual results with "real" transistors having a wide range of current gain and Vbe will be much different. Change the current gain in the program to see if the circuit still works.(2) RPI is the i/p impedance looking into the base of Q1, so, the total i/p impedance is: R1//R2//RPI = 1.8K ohm. so we can look at the i/p portion of the circuit as: Vs connected in series with Rs then to C1 then connected inseries to that 1.8k. Quote Link to comment Share on other sites More sharing options...

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