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Unformatted text preview: ECE 488: RF Circuits and Systems Spring 2009 LAB 1: Real Inductors, Q Factors, and Impedance Matching Reference: Lectures 1-3; Chapter 2. Due: At the time of your next lab. Your Name: Your Net ID: Partner(s): Bench Number: Lab Date: Scores # 1-27/80 # 28-30/20 Total Lab TA: Circle Lab Section: Mon, Mon-Eve, Wed Introduction This lab has two parts. In the first, you will deter- mine the unloaded Q of a real inductor (one that has losses). Then in the second part, you will use an L network to match a 435 resistive load to a genera- tor with a 72 source impedance. Refer to Chapter 2 of the text and your class notes for help with this lab. Also, see the introductions to using the oscil- loscope and function generator under the Handouts section of the ECE 488 web site. Pre-Lab work: Homework 1 provides some key background for this lab. Make sure you have the required formulas entered into the boxes under Fro- mulas Needed below. Lab reports: Your report for this lab is due at the beginning of your next lab and as a minimum should include (1) this lab description with all boxed questions answered, and Figure 1: Resonant circuit for finding R P . The com- ponents in the dashed boxes cannot be physically isolated. ( Reminder: At resonance, the combination of the real inductor and an ideal capacitor is equivalent to the pure resistance, R P .) (2) one extra 8-1/2 x11 sheet for the detailed typed answers and plots as requested in the After Your Lab section. Number the sections of any attached notes to corre- spond with the numerical sequence given here. Before Your Lab Formulas Needed: Fill in the boxes under items 14 using your results from Homework 1 and some additional calculations. 1. Enter the expression for R P as a function of R and the voltages at points A and B on the circuit of Figure 1). R P 2. Enter the expression for the value of the inductor in terms of a known capacitance and the resonant frequency from the circuit of Figure 1). L = H 3. Compute the component values for the L network shown in Figure 2 that matches a 435 load to a 72 generator at a frequency of 656-kHz. Q EL = X P = R HI /Q EL = X S = R LO Q EL = L = H C = pF 4. Enter the expression for the L-network effi- ciency of Figure 2 from Homework 1, Problem 5. = % Figure 2: L-Network Matching. When this circuit is built in the lab, R G = 72 will be the 50 internal source impedance of the generator plus an external 22 series resistor. CORNELL UNIVERSITY c circlecopyrt WES SWARTZ (09/1/23) LAB 11 ECE 488: RF Circuits and Systems Spring 2009 LAB 1: Real Inductors, Q Factors, and Impedance Matching In the Lab Answers needed: The answers in this section are needed for the Final Calculations section. The TA will give you some basic instruction on the use of the digital scopes and other equipment, but you should familiarize yourselves with the functions of each piece. Dont forget about the AUTOSET but- ton on the scopes!...
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