SPICE-Simulation using LTspice IV

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9.3. Parametric Sweep If you have a look at “<strong>LTspice</strong> / Dot Commands“ in the online help, then you will find a lot of commands and capabilities. Let us test the <strong>SPICE</strong>-command .step This is important because with „step“ you can automatically vary the value of a part or a voltage and repeat the simulation. Let’s take the circuit of the last section and vary the upper resistor R1 in the base voltage divider in 5 steps from 10k to 15k. This will enable you to get the optimum operating point. Note: a) The peak value of the input voltage is now 0.3V b) The value of R1 is replaced by the variable {Rx} c) With the spice directive .step param Rx 10k 15k 1k the value of Rx is increased from 10k to 15k in steps of 1k. Now press the simulation button ( the “running guy”). The simulation will run, but you don’t see any results. So move your cursor to the collector of the transistor Q2 and click. 60
You will see this result and that a value of approx. 15k for R1 (= lowest curve) will do the job perfectly (and give a V DC = +6.5V at the collector of Q2) 61
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SPICE-Simulation using LTspice IV T
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8. Project 4: U-I-Curves of Parts 4
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1. Introduction Modern electronics
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3.2. Presentation of Simulation Res
Page 9 and 10: 3.4. Changing Curve Colours A very
Page 11 and 12: Task: Make the voltage curve visibl
Page 13 and 14: Step 2: Enter the new border values
Page 15 and 16: 3.7. Differential Measurements Ever
Page 17 and 18: 3.9. Changing Part Values Now we wa
Page 19 and 20: 4.2. Changing Part Values This is d
Page 21 and 22: Now start the simulation, click on
Page 23 and 24: 4.3.3. The Impulse Response Fourier
Page 25 and 26: This is the correct presentation: -
Page 27 and 28: 4.4.2. Square Wave (f = 1691 Hz) St
Page 29 and 30: 4.5. Frequency Domain Simulation: A
Page 31 and 32: 5. FFT (= Fast Fourier Transformati
Page 33 and 34: Select Input Voltage V(n001) by a m
Page 35 and 36: 6.2. Important: creating SPICE Mode
Page 37 and 38: 6.2.2. Creation of the Symbol for a
Page 39 and 40: For an ideal transformer you can re
Page 41 and 42: Step 5: self-explainig…. 41
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Page 45 and 46: When simulating for 200ms, you will
Page 47 and 48: 8. Project 4: V-I-Curves of Parts 8
Page 49 and 50: 8.3. NPN Transistor In the „examp
Page 51 and 52: 8.4. N-Channel Junction FET First w
Page 53 and 54: In the simulation we would like to
Page 55 and 56: 9.2. Two Stage Broadband Amplifier
Page 57 and 58: 9.2.4. DC Bias If you want to know
Page 59: 9.2.5. Frequency Domain Simulation:
Page 63 and 64: Using the cursor you will find the
Page 65 and 66: Let us now draw the complete circui
Page 67 and 68: 10.3. Use of Labels In general OP A
Page 69 and 70: 11. Project 7: DC-DC Converters Fir
Page 71 and 72: 11.2. The Step Up Converter The sch
Page 73 and 74: If you want: vary the gate voltage,
Page 75 and 76: 11.4. The Step Down Converter In th
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SPICE-Simulation using LTspice IV

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