4902_C2007__bandgap_lab - CA3046 array go ahead and blast...

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BANDGAP VOLTAGE REFERENCE Here's the bandgap circuit covered in Friday's lecture: The CA3046 is a 5 NPN transistor array. Its data sheet is available on the course website. You will probably need to adjust the 240 resistor value to achieve the bandgap voltage of V BG = 1.205V. Once that's done, check the various voltages throughout the circuit (is the V BE across the 51 what you expected based on the analysis in lecture?). Note the room temperature values of V BE1 , V BE2 , V BE , and V BG . If you have access to a heat gun (or hair dryer, or some other means of heating up the
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Unformatted text preview: CA3046 array), go ahead and blast some hot air on the CA3046 chip. Measure the new values of V BE1 , V BE2 , ∆ V BE , and V BG . Do the changes correspond to what you expected based on the analysis in lecture? Note that the behavior may not be as good as expected: the lecture analysis depends on the ratio between resistors R 1 and R 2 tracking over temperature. This will happen when both resistors are on the silicon die, but with discrete resistors in the lab the tracking will not be as good. V BE2 V BE1 R 1 R 2...
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