# hw8_soln - [1 jωR S C π C μ(1 g m r o[1 jωr o C CS C...

This preview shows pages 1–2. Sign up to view the full content.

UNIVERSITY OF CALIFORNIA AT BERKELEY College of Engineering Department of Electrical Engineering and Computer Sciences Homework #8 Solutions Due Tuesday, October 23, 2007 EE 105 Fall 2007 Prof. Liu Problem 1. Impact of Early Effect on A v for a Common-Base Stage (Miller Approximation) At node X , we add a resistor to ground with value R X = r o 1 - A v = r o 1 - g m R C . At the output, we add a resistor to ground with value R o = r o 1 - 1 /A v = r o 1 - 1 gmR C = g m r o R C g m R C - 1 . Once we split r o in this manner, the circuit takes the form of the example in Lecture 11, Slide 7, so we can apply the gain equation listed there (where R E R X , R C R C bardbl R o , and R B 0): A v = R C bardbl R o 1 /g m + R S bardbl R E · R E R S + R E = R C bardbl g m r o R C g m R C - 1 1 /g m + R S bardbl r o 1 - g m R C · r o 1 - g m R C R S + r o 1 - g m R C Problem 2. Frequency Response of a Common-Emitter Stage a) ω p,in = 1 R S C in C in = C π + C μ (1 A v ) A v = g m r o C in = C π + C μ (1 + g m r o ) ω p,in = 1 R S ( C π + C μ (1 + g m r o )) ω p,out = 1 r o C out C out = C CS + C μ (1 1 /A v ) = C CS + C μ (1 + 1 /g m r o ) ω p,out = 1 r o [ C CS + C μ (1 + 1 /g m r o )] b) A 0 = g m r o r π R S + H ( ) = g m r o r π

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

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: [1 + jωR S ( C π + C μ (1 + g m r o ))] [1 + jωr o [ C CS + C μ (1 + 1 /g m r o )]] Problem 3. Common-Base Stage Design 1 a) Assuming the output node dominates, we have: 2 π × 10 10 ≤ ω p,out = 1 R C ( C μ + C CS ) R C ≤ 637 Ω b) We know that the DC gain is A v = g m R C 1+ g m R S . We can see that picking a larger R C will result in a larger gain but a smaller bandwidth and vice-versa. Thus, our trade-of is between gain and bandwidth. Problem 4. Frequency Response o± Emitter Follower C in = C μ + C π (1 − A v ) A v = R E 1 /g m + R E C in = C μ + C π p 1 − R E 1 /g m + R E P ≤ 50 ±F g m = I C /V T = 1 / 26 S R E ≥ 39 Ω 2...
View Full Document

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern