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university:courses:electronics:electronics-lab-pn-junction-cap [05 Mar 2019 10:56] Antoniu Miclaus [Advanced Credit measurements:] |
university:courses:electronics:electronics-lab-pn-junction-cap [23 Aug 2019 11:46] Pop Andreea |
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| - | ====== Activity, The voltage dependent capacitance of the PN junction ====== | + | ====== Activity: The voltage dependent capacitance of the PN junction ====== |
| ===== Objective: ===== | ===== Objective: ===== | ||
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| ===== Hardware Setup: ===== | ===== Hardware Setup: ===== | ||
| - | Using the Network Analyzer instrument in the Scopy software obtain a gain (attenuation) vs. frequency plot from 5 kHz to 10 MHz. Scope channel 1 is the "filter" input and scope channel 2 is the "filter" output. Set AWG offset to 1V and the Amplitude to 200mV. The offset value is not important at this point when measuring a simple real capacitor but will be used as the reverse bias voltage when we measure diodes in later steps. Set the vertical scale to start at 1dB to -50 dB range. Run a single sweep and export the data to a .csv file. You should notice a high pass characteristic that has a high attenuation at very low frequencies where the impedance of the capacitor is large compared to R<sub>1</sub>. At the very high end of the frequency sweep there should be a relatively flat region where the impedance of the C<sub>1</sub>, C<sub>m</sub>capacitive voltage divider is much lower than R<sub>1</sub>. | + | Using the Network Analyzer instrument in the Scopy software obtain a gain (attenuation) vs. frequency plot from 5 kHz to 10 MHz. Scope channel 1 is the "filter" input and scope channel 2 is the "filter" output. Set AWG offset to 1V and the Amplitude to 200mV peak-to-peak . The offset value is not important at this point when measuring a simple real capacitor but will be used as the reverse bias voltage when we measure diodes in later steps. Set the vertical scale to start at 1dB to -50 dB range. Run a single sweep and export the data to a .csv file. You should notice a high pass characteristic that has a high attenuation at very low frequencies where the impedance of the capacitor is large compared to R<sub>1</sub>. At the very high end of the frequency sweep there should be a relatively flat region where the impedance of the C<sub>1</sub>, C<sub>m</sub>capacitive voltage divider is much lower than R<sub>1</sub>. |
| {{ :university:courses:electronics:apn_f3.png?600 |}} | {{ :university:courses:electronics:apn_f3.png?600 |}} | ||
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| {{ :university:courses:electronics:apn_f7_ss.png? |}} | {{ :university:courses:electronics:apn_f7_ss.png? |}} | ||
| - | <WRAP centeralign> Figure 4 Scopy shot with offset at 0V</WRAP> | + | <WRAP centeralign> Figure 7 Scopy shot with offset at 0V</WRAP> |
| Replace the 1N4001 diode with the 1N3064 diode from the Kit and repeat the same set of sweeps you just did for the first diode. Fill out another table with your measured data and calculated C<sub>diode</sub> values. How do the 1N3064 values compare to those for the 1N4001 diode? You should include a plot of the diode capacitance vs. reverse bias voltage for each diode you measure in your lab report. | Replace the 1N4001 diode with the 1N3064 diode from the Kit and repeat the same set of sweeps you just did for the first diode. Fill out another table with your measured data and calculated C<sub>diode</sub> values. How do the 1N3064 values compare to those for the 1N4001 diode? You should include a plot of the diode capacitance vs. reverse bias voltage for each diode you measure in your lab report. | ||
university/courses/electronics/electronics-lab-pn-junction-cap.txt · Last modified: 27 Jan 2021 22:36 by Robin Getz