hw04sol - ECE 3150 Homework 4 Solution Spring 2009 1....

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ECE 3150 Homework 4 Solution Spring 2009 1. (Bipolar transistor operating regions) For the following silicon BJT conditions, state the operating region (notice the voltage convention, e.x., V BE =V B – V E = - V EB . The “common” node below is the same reference node for both input and output, as illustrated in Figs. 1.17 and 1.18 in the class notes.) (a) NPN with V BE = 0.7V and V CE = 0.0V in common-emitter notation. (2 pts) Notice that “common” means that the other two terminals use it as a voltage reference (often ground). You need to translate to the junction voltage to find the operating region. This problem helps you get familiar with the different BJT circuit configurations. V BE = 0.7 V forward-biased emitter-base junction V CE = 0 V V BC = V BE – V CE = 0.7 V forward-biased collector-base junction SATURATION operation (b) NPN with V BE = 0.9V and V CE = 2.0V in common-emitter notation. (2 pts) V BE = 0.9 V forward-biased emitter-base junction V CE = 2.0 V V BC = -1.1 V reverse-biased collector-base junction FORWARD ACTIVE operation (c) NPN with V BC = 0.7V and V EC = - 2.0V in common-collector notation. (2 pts) V BC = 0.7 V forward-biased collector-base junction V EC = -2.0 V V BE = V BC – V EC = 2.7 V forward-biased emitter-base junction SATURATION operation (d) NPN with V EB = 0.3V and V CB = 2.0V in common-base notation. (2 pts) V EB = 0.3 V reverse-biased emitter-base junction V CB = 2.0 V reverse-biased collector-base junction CUTOFF operation (e) PNP with V BE = - 0.9V and V CE = - 2.0V in common-emitter notation. (2 pts) V BE = -0.9 V forward-biased emitter-base junction V CE = -2.0 V V BC =1.1 V reverse-biased collector-base junction FORWARD ACTIVE operation (f) PNP with V EB = 0.9V and V CB = - 2.0V in common-base notation. (2 pts) V EB = 0.9 V forward-biased emitter-base junction V CB = -2.0 V reverse-biased emitter-base junction FORWARD ACTIVE operation 2. (Large-signal and small-signal BJT models) For an ideal NPN BJT at 300K, (a) Draw the large-signal Ebers-Moll model with the current gain parameters of α F and α R (pay attention to the direction of the dependent current source) (6 pts) (b) If we have designed the BJT with a large current gain by N E >>N B >>N C and W B <<L n , denote the main current components (in terms of electron-hole drift-diffusion- recombination terms) in the forward active mode for I E , I B and I C . (6 pts) From the electron-hole drift-diffusion-recombination point of view: For NPN BJT in forward active mode: I E is dominated by the injection of electrons from the emitter into the base, which is equivalent to the minority electron diffusion current at the base edge of the emitter-base junction I En = (qD n n Bpo A E /W B ) × [exp{qV BE /kT} – 1] This can be obtained by assuming W B << L n , N B >> N C linearly decreasing base minority electron density from n po exp (qV BE /kT) at the base edge of emitter-base junction...
View Full Document

This note was uploaded on 03/11/2009 for the course ECE 3150 taught by Professor Spencer during the Spring '07 term at Cornell University (Engineering School).

Page1 / 10

hw04sol - ECE 3150 Homework 4 Solution Spring 2009 1....

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online