Wednesday, March 11, 2020

don johson essays

don johson essays The objective of this lab is to introduce the Bipolar Junction Transistor (BJT). A BJT is a three terminal device composed of an emitter, base, and collector terminals. In this lab we will introduce two major types of BJTs : npn and pnp. The first, npn, has an n-type emitter, a p-type base and a n-type collector. On the other hand the pnp has a p-type emitter, a n-type base, and a p-type collector. Also the transistor consists of two major pn junctions, the emitter-base junction (EBJ) and the collector-base junction (CBJ). Depending on the bias condition of each of these junctions, there are different modes of operation. We will show that the basic principle of a BJT is the use of the voltage between two terminals on order to control the current in the third terminal. In this part of the lab we will use the curve tracer to display the common-emitter BJT family of curves. We will see the i-v characteristics of Ic vs. Vce for steps of IB. The i-v characteristic showing Ic vs. Vce for different values of VBE are not linear. Thus we will see that the output resistance of the BJT change slightly with current. Then using the values of Ic and Ro, we can calculate the early voltage, Va. The important feature of this device is that the i-v characteristics are not perfect linear. 1) Use the curve tracer to display the common-emitter BJT family of curves (ic vs vCE for steps of iB). 2) Determine IB needed to set the Q-Point for Ic=0.5mA and VCE=5 Volts. 4) Determine AC = IC/IB. 5) Determine the output resistance, Ro, by measuring the slope of the i-v curve and taking the inverse of that. 6) Does the output resistance change with voltage on the same curve? 7) Does the output resistance change with current on different curves? IB is found to be 5A according to curve tracer. 4) AC = IC/IB. IC1 = 420A , IB1 = 4A, VCE = 5 Volts IC2 = 680&...

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