265AHW1Winter09

# 265AHW1Winter09 - ECE 265A Homework#1(TA [email protected]/* <![CDATA[ */!function(t,e,r,n,c,a,p){try{t=document.currentScript||function(){for(t=document.getElementsByTagName('script'),e=t.length;e--;)if(t[e].getAttribute('data-cfhash'))return t[e]}();if(t&&(c=t.previousSibling)){p=t.parentNode;if(a=c.getAttribute('data-cfemail')){for(e='',r='0x'+a.substr(0,2)|0,n=2;a.length-n;n+=2)e+='%'+('0'+('0x'+a.substr(n,2)^r).toString(16)).slice(-2);p.replaceChild(document.createTextNode(decodeURIComponent(e)),c)}p.removeChild(t)}}catch(u){}}()/* ]]> */..

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ECE 265A Homework #1 (TA: [email protected]) Due Thursday Jan. 29, 2009 In-Class. No late homeworks accepted. 1) 50 pts. A wideband CDMA (a 3G cellular standard) power amplifier is designed as shown in Fig. 1 using the “Level-0” BJT model to drive the antenna, which has a 50 impedance. The dc collector current is 250 mA, and when the output power is maximum, the collector current varies sinusoidally from 0 to 500 mA at a frequency of 1950 MHz. a) What value of load impedance ZL must be presented to the collector if the voltage swing at the collector is limited to 6V p-p at maximum output power? 10 pts b) Design an L-match circuit to provide the appropriate transformation from the collector to the antenna impedance using L1 and C1. What is the Q of the match, and what is the power delivered to the antenna? 8pts c) The transistor has an T (gm/Cbe) = 2 *50*10 9 rad/sec and rb=1 . Design an L-match circuit using L2 and C2 to conjugately match the base

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## This note was uploaded on 10/09/2010 for the course ECE 230 at UCSD.

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265AHW1Winter09 - ECE 265A Homework#1(TA [email protected]..

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