Design & Analysis of Small Signal Bipolar Transistor Model _Common-Emitt...

This model shows the use of a small-signal equivalent transistor model to assess performance of a common-emitter amplifier. The 47K resistor is the bias resistor required to set nominal operating point, and the 470 Ohm resistor is the load resistor. The transistor is represented by a hybrid-parameter equivalent circuit with circuit parameters h_ie (base circuit resistance), h_oe (output admittance), h_fe (forward current gain), and h_re (reverse voltage transfer ratio). Parameters set are typical for a BC107 Group B transistor. The gain is approximately given by -h_fe*470/h_ie =-47. The 1uF decoupling capacitor has been chosen to present negligible impedance at 1KHz compared to the input resistance h_ie, so the output voltage should be 47*10mV = 0.47V peak.

Design & Analysis of Noninverting Amplifier using Op-Amp_ MATLAB Simulink

This model shows a noninverting op-amp circuit. The gain is given by 1+R2/R1, and with the values set to R1=1K Ohm and R2=10K Ohm, the 0.1V peak-to-peak input voltage is amplified to 1.1V peak-to-peak. As the Op-Amp block implements an ideal (i.e. infinite gain) device, this gain is achieved regardless of output load.

Design & Analysis of Inverting Amplifier using Op-Amp_ MATLAB Simulink ...

    This model shows a standard inverting op-amp circuit. The gain is given by -R2/R1, and with the values set to R1=1K Ohm and R2=10K Ohm, the 0.1V peak-to-peak input voltage is amplified to 1V peak-to-peak. As the Op-Amp block implements an ideal (i.e. infinite gain) device, this gain is achieved regardless of output load.

Design & Analysis of Full-Wave Bridge Rectifier_Using MATLAB Simulink

    This example shows an ideal AC transformer plus full-wave bridge rectifier. It converts 120 volts AC to 12 volts DC. The transformer has a turns ratio of 14, stepping the supply down to 8.6 volts rms, i.e. 8.6*sqrt(2) = 12 volts pk-pk. The full-wave bridge rectifier plus capacitor combination then converts this to DC. The resistor represents a typical load.

The model can be used to size the capacitor required for a specified load. For a given size of capacitor, as the load resistance is increased, the ripple in the DC voltage increases. The model can also be used to drive an application circuit in order to assess the effect of the ripple.

Design & Analysis of Finite-Gain Op-Amp_Matlab Based Approach

    This example shows how higher fidelity or more detailed component models can be built from the Foundation library blocks. The Op-Amp block in the Foundation library models the ideal case whereby the gain is infinite, input impedance infinite, and output impedance zero. The Finite Gain Op-Amp block in this example has an open-loop gain of 1e5, input resistance of 100K ohms and output resistance of 10 ohms. As a result, the gain for this amplifier circuit is slightly lower than the gain that can be analytically calculated if the op-amp gain is assumed to be infinite. Plot "Finite Gain Op-Amp Circuit Voltages" shows the input and output voltages for the circuit. If the circuit used an infinite gain op-amp with no input and output resistances defined, the gain would be 1+R2/R1 = 51. Since this model uses an op-amp with finite gain plus input and output resistances, the circuit gain is slightly less.