Transient Analysis

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In the Transient analysis, we will study the performance of the circuit AMPLIF.EPB in time frame. For example, the amplifier is fed with an input signal that varies with time in specified manner. Transient Analysis is used to view the input and output with respect to time.

We have analyzed the amplifier small signal properties. At 10kHz, amplification is 40dB (output amplitude is about 90 times greater than input signal), this means that we can apply max. of about 50mV on input without distortion:

1. We will now define the amplitude of the generator signal. Right click and the Set Parameter option tool from the function tool Set parameters/ models and click the left mouse button on the input generator G to observe a dialog box.

2. The Voltage Generator is in the SINE mode and produces 10mV, 10kHz signal. This would be amplified without distortion. As we found from AC Sweep analysis, the maximum amplitude that may be specified was about 50 mV. Click the CANCEL button to exit from this dialog box.

3. Right click and select the Delete tool and delete all previously used Waveform Testpoints.

4. Right click and select the Voltage Waveform option tool from the function tool Waveform Marker and define new Voltage testpoints on the nets, on generator input (between generator G and resistance RG), on transistor Base, on transistor Collector and on amplifier load (between C2 and RL).

5. Select the Current Waveform option tool from the function tool Waveform Marker and define new Current testpoints on the pins: generator “-” pin, transistor collector pin, load resistor RL (upper pin).

6. Click Analysis in the main menu. A window Setup Simulation Parameters opens with the option Analysis being highlighted on the left side of the window by default. Set the parameters by selecting GENERAL SETTINGS from the tree view on the left side of the window. Select Transient Analysis. Specify the timing parameter. Set the Analog Sim. Step time to 1 microsecond, Simulation Time Limit to 200 micro second (two generator periods). Initialize LC parameter should be set to Solve.

7. Click the ACCEPT button which automatically switches Analysis option. Here, check Transient Analysis and click START button. The result is displayed as a diagram if Display Waveform is checked.

8. We may change the Generator parameter Ao from 10mV to 100mV and rerun the Transient Analysis. See that there is a distortion in the output waveform.

9. Reset the value of Ao to 10mV.

Transient Analysis on Digital circuits

From the File menu of the Project Explorer, select Open Project. Select Counter.EPB file name from the file list in the Open dialog box and then click the OK button.

Right click on the task CIRCUIT in the Project Explorer to unfold a list of functions and select Mixed Mode Simulator. Preprocessing of the circuit takes place.

Before starting the Transient Analysis, the circuit state must be initialized. Analog part of the circuit has one state variable: voltage on the capacitor C. We may assume that it starts from the zero value (the power-up condition). This may be achieved by the proper setting of the Transient Analysis/ Initialize LC option in the Setup Simulation Parameters dialog box invoked from the Analysis menu.

1. Initialization of the digital part of the circuit is essential as outputs of the inverters, and output state of the D Flip-flop must be considered. We have to input a Clock pulse to analyze the working of the circuit.

2. Right click and select the option tool Clock Generator from the function tool Preset Logic State and click on the 7404,1 (U1) and enter the generator string value of (L10us,H10us). This indicates a continuous clock pulse having a 10µs Low and 10µs High pulse width.

3. Enter 5V to the Voltage source from the Set parameters/ models tool and clicking on the Voltage Source.

4. Place Logic state marker on the input node of U1 and on output nodes (Q) of all D-Flip flops using the option tool Logic Waveform enabled from the function tool Waveform Marker.

5. Click Analysis in the main menu. A window Setup Simulation Parameters opens with the option Analysis being highlighted on the left side of the window by default. Set the parameters by selecting GENERAL SETTINGS from the tree view on the left side of the window. Select Transient Analysis and set Analog Sim. Step Time to 10 microsecond. Set Simulation Time Limit to 500 microsecond. Set Initialize LC to Solve. Click the ACCEPT button to automatically switch to the Analysis option and select the START button to begin the analysis.

6. After the analysis is completed, the result is displayed as a diagram if Display Waveform is checked. Value of the Analog Simulation Step Time defines time step used in the analog integration process resolving the capacitor voltage. It also defines sampling rate of analog data output to the diagram display module. The shorter the Analog Sim. Step Time, better is the accuracy of analog integration and density of analog graphic results obtained.