LAB5-09 - (i.e 1 S I and thus 2 S I 3 Use your I C2-2 C V...

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ECE 225 ELECTRONIC CIRCUITS LABORATORY EXPERIMENT #5 CURRENT SOURCES Purpose : Construct simple current source, Widlar current source and Wilson current source, and measure their characteristics. Prelab : Derive all the analytical equations for computing the required measurements in PART A), B) and C). With these equations, you will compare your experimental results with your theoretical results. A) Simple Current Source 1. Measurement of the output resistance of a BJT simple current source by dc measurements. Construct the circuit shown in Fig. 1. Let 2 CC V be provided by a variable dc output source. Vary 2 CC V and measure 2 C V . Step 2 CC V values from 0 volts to 10 volts. At each value of 2 C V , measure the dc voltage drop across the 1K resistor to find 2 C I . 2. Determine the reference current, REF I , and the base-to-emitter voltage, 1 BE V , for a single value of 2 C V =2 volts. From these data, find the saturation current for Q1
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Unformatted text preview: (i.e. 1 S I ) , and thus 2 S I . 3. Use your I C2-2 C V data to find 2 o r , (the output resistance of Q2), A V (the early voltage of Q2), and o I (the nominal output current). B) Widlar Current Source 1. Construct a BJT Widlar current source shown in Fig. 2. Use the dc technique outlined in (A) to find the nominal output current and the output resistance, 2 2 2 (1 ) OUT o m R r g R = + where 2 2 / o A C r V I = . 2. Measure REF I where 2 C V is about 2 volts. C) Wilson Current Source 1. Construct a Wilson current source shown in Fig. 3, using three identical transistors with a β value. Set 2 C V to several values between 1 volt and 12 volts and measure the voltage drop across the 1K resistor. Also measure BE V for several values of CE V and calculate a value for S I . From these data, find , , , o A o I V r and o R ....
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LAB5-09 - (i.e 1 S I and thus 2 S I 3 Use your I C2-2 C V...

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