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--- university:courses:electronics:electronics-lab-7 [23 Mar 2017 16:08] – [Materials:] Doug Mercer
+++ university:courses:electronics:electronics-lab-7 [23 Aug 2019 12:52] – Antoniu Miclaus
@@ Line 1: / Line 1: @@
-====== Activity 7. Zero gain amplifier (BJT) ======
+====== Activity: Zero gain amplifier (BJT) ======
 ===== Objective: =====
@@ Line 25: / Line 25: @@
 ===== Hardware Setup: =====
-The waveform generator 1 should be configured for a 1 KHz triangle wave with 1.5 volt amplitude and 1.5V offset. Connect scope Channel 1 to display output W1 of the AWG generator. The Single ended input of scope channel 2 (2+) is used to measure alternately the base and collector voltage of Q<sub>1</sub>.
+The waveform generator 1 should be configured for a 1 KHz triangle wave with 3 volt amplitude peak-to-peak and 1.5V offset. Connect scope Channel 1 to display output W1 of the AWG generator. The Single ended input of scope channel 2 (2+) is used to measure alternately the base and collector voltage of Q<sub>1</sub>.
+{{:university:courses:electronics:zero_gain-bb.png|}}
+<WRAP centeralign> Figure 2 Zero Gain Amplifier Breadboard Circuit </WRAP>
 ===== Procedure: =====
@@ Line 32: / Line 36: @@
 In the figure below we have a transistor biased into conduction with a collector voltage which is less than the base voltage by kT/q, (equal to Ic times 47Ω) and is essentially constant with input voltage changes applied from the AWG generator.
+<WRAP centeralign>{{:university:courses:electronics:zero_gain_vbe-wav.png?500|}}</WRAP>
+<WRAP centeralign> Figure 3 Scopy Plot V<sub>BE</sub>  </WRAP>
+<WRAP centeralign>{{:university:courses:electronics:zero_gain_vce-wav.png?500|}}</WRAP>
+<WRAP centeralign> Figure 4 Scopy Plot V<sub>CE</sub>  </WRAP>
 {{ :university:courses:electronics:a7_f2.png?500 |}}
-<WRAP centeralign> Figure 2 Plot comparing V<sub>BE</sub> and V<sub>CE</sub> </WRAP>
+<WRAP centeralign> Figure 5 Excel Plot comparing V<sub>BE</sub> and V<sub>CE</sub> </WRAP>
-{{ :university:courses:electronics:a7_f3.png?500 |}}
-<WRAP centeralign> Figure 3 V<sub>BE</sub> and V<sub>CE</sub> vs. collector current </WRAP>
+{{ :university:courses:electronics:a7_f3.png?500 |}}
+<WRAP centeralign> Figure 6 Excel V<sub>BE</sub> and V<sub>CE</sub> vs. collector current </WRAP>
 ===== Questions: =====
@@ Line 60: / Line 72: @@
 ===== Directions: =====
-The breadboard connections are as shown in figure 4 below. The output of the AWG generator drives one end of resistor R<sub>1</sub> as well as the 2+ input of scope channel 2. The emitter of Q<sub>1</sub> is connected to ground. The base and collector of Q<sub>1</sub> are connected to the emitter of Q<sub>2</sub>. The base and collector of Q<sub>2</sub> are connected to the other end of R<sub>1</sub> and to the 2- input of scope channel 2 and the 1+ input of scope channel 1.
+The breadboard connections are as shown in figure 7 below. The output of the AWG generator drives one end of resistor R<sub>1</sub> as well as the 2+ input of scope channel 2. The emitter of Q<sub>1</sub> is connected to ground. The base and collector of Q<sub>1</sub> are connected to the emitter of Q<sub>2</sub>. The base and collector of Q<sub>2</sub> are connected to the other end of R<sub>1</sub> and to the 2- input of scope channel 2 and the 1+ input of scope channel 1.
 {{ :university:courses:electronics:a7_f4.png?300 |}}
-<WRAP centeralign> Figure 4 2 V<sub>BE</sub> circuit </WRAP>
+<WRAP centeralign> Figure 7 V<sub>BE</sub> circuit </WRAP>
 ===== Hardware Setup: =====
-The waveform generator should be configured for a 1 KHz triangle wave with 1.5 volt amplitude and 1.5V offset. Both scope channels can be set to 200mV per division.
+{{:university:courses:electronics:vbe_circuit-bb.png|}}
+<WRAP centeralign> Figure 8 V<sub>BE</sub> Breadboard circuit </WRAP>
+The waveform generator should be configured for a 1 KHz triangle wave with 3 volt amplitude peak-to-peak and 1.5V offset. Both scope channels can be set to 200mV per division.
 ===== Procedure: =====
+<WRAP centeralign>{{:university:courses:electronics:vbe_circuit-wav.png?500|}}</WRAP>
+<WRAP centeralign> Figure 9 Scopy Voltage vs. current </WRAP>
 {{ :university:courses:electronics:a7_f5.png?500 |}}
-<WRAP centeralign> Figure 5 Voltage vs. current </WRAP>
+<WRAP centeralign> Figure 10 Voltage vs. current </WRAP>
 You should also confirm that the voltage characteristic measured at the collector, base of transistor Q<sub>1</sub> is the same as was measured in activity 3.
@@ Line 95: / Line 116: @@
 {{ :university:courses:electronics:a7_f6.png?300 |}}
-<WRAP centeralign> Figure 6 V<sub>BE</sub> Multiplier circuit </WRAP>
+<WRAP centeralign> Figure 11 V<sub>BE</sub> Multiplier circuit </WRAP>
 ===== Hardware Setup: =====
-The waveform generator should be configured for a 1KHz triangle wave with 1.5 volt amplitude and 1.5V offset. Both scope channels can be set to 200mV per division.
+{{:university:courses:electronics:vbe_multiplier1-bb.png|}}
+<WRAP centeralign> Figure 12 V<sub>BE</sub> Multiplier Breadboard circuit </WRAP>
+The waveform generator should be configured for a 1KHz triangle wave with 3 volt amplitude peak-to-peak and 1.5V offset. Both scope channels can be set to 200mV per division.
 ===== Procedure: =====
 Start out with variable resistor R<sub>4</sub> set to its minimum value of nearly zero ohms. Observe the voltage vs. current characteristics of this configuration compared to version 1. There is a small extra current that flows in the two 10KΩ resistors before the transistor turns on. The voltage at 1mA is slightly higher and the slope of the curve is not as steep.
+<WRAP centeralign>{{:university:courses:electronics:vbe_multiplier-wav1.png?500|}}</WRAP>
+<WRAP centeralign> Figure 13 Scopy plot - R<sub>4</sub> set to zero ohms </WRAP>
 {{ :university:courses:electronics:a7_f7.png?500 |}}
-<WRAP centeralign> Figure 7 R<sub>4</sub> set to zero ohms </WRAP>
+<WRAP centeralign> Figure 14 Excel plot - R<sub>4</sub> set to zero ohms </WRAP>
 Let’s apply the concept of the zero gain amplifier. Now adjust R<sub>4</sub> and observe the slope of the curve change. At what value of R<sub>4</sub> is the curve nearly vertical? Why is that value the correct value for “zero” gain?
+<WRAP centeralign>{{:university:courses:electronics:vbe_multiplier-wav2.png?500|}}</WRAP>
+<WRAP centeralign> Figure 15 Scopy plot - R<sub>4</sub> set to approximately 100 ohms </WRAP>
 {{ :university:courses:electronics:a7_f8.png?500 |}}
-<WRAP centeralign> Figure 8 R<sub>4</sub> set to approximately 100 ohms </WRAP>
+<WRAP centeralign> Figure 16 Excel plot - R<sub>4</sub> set to approximately 100 ohms </WRAP>
 ====== VBE times 2 version 3: ======
@@ Line 128: / Line 161: @@
 ===== Directions: =====
-The breadboard connections are as shown in the diagram below in figure 9. Version 3 is made from version 2 by removing 10KΩ resistor R<sub>2</sub> and replacing it with diode connected NPN Q<sub>2</sub> as shown.
+The breadboard connections are as shown in the diagram below in figure 17. Version 3 is made from version 2 by removing 10KΩ resistor R<sub>2</sub> and replacing it with diode connected NPN Q<sub>2</sub> as shown.
 {{ :university:courses:electronics:a7_f9.png?300 |}}
-<WRAP centeralign> Figure 9 Version 3 of V<sub>BE</sub> multiplier </WRAP>
+<WRAP centeralign> Figure 17 Version 3 of V<sub>BE</sub> multiplier </WRAP>
 ===== Hardware Setup: =====
-The waveform generator should be configured for a 1KHz triangle wave with 1.5 volt amplitude and 1.5V offset. Both scope channels can be set to 200mV per division.
+{{:university:courses:electronics:vbe_multiplier3-bb.png|}}
+<WRAP centeralign> Figure 18 Version 3 of V<sub>BE</sub> multiplier Breadboard Circuit</WRAP>
+The waveform generator should be configured for a 1KHz triangle wave with 3 volt amplitude peak-to-peak and 1.5V offset. Both scope channels can be set to 200mV per division.
 ===== Procedure: =====
 Again start out with variable resistor R<sub>4</sub> set to its minimum value of nearly zero ohms. Observe the voltage vs. current characteristics of this configuration compared to version 2. There is a small extra current that flows in the one 10K resistors after Q<sub>1</sub> turns on and until both Q<sub>1</sub> and Q<sub>2</sub> are on. The voltage at 1 mA is slightly lower and the slope of the curve is steeper more like version 1.
+<WRAP centeralign>{{:university:courses:electronics:vbe-multiplier3-wav1.png?500|}} </WRAP>
+<WRAP centeralign> Figure 19 </WRAP>
 {{ :university:courses:electronics:a7_f10.png?500 |}}
-<WRAP centeralign> Figure 10 </WRAP>
+<WRAP centeralign> Figure 20 </WRAP>
 Again, let’s apply the concept of the zero gain amplifier. Now adjust R<sub>4</sub> and observe the slope of the curve change. At what value of R<sub>4</sub> is the curve nearly vertical? Why is that value the correct value for “zero” gain?
+<WRAP centeralign>{{:university:courses:electronics:vbe-multiplier3-wav2.png?500|}} </WRAP>
+<WRAP centeralign> Figure 22 </WRAP>
 {{ :university:courses:electronics:a7_f11.png?500 |}}
-<WRAP centeralign> Figure 11 </WRAP>
+<WRAP centeralign> Figure 22 </WRAP>
 Optional extra credit problem:
@@ Line 156: / Line 201: @@
 {{ :university:courses:electronics:a7_f12.png?500 |}}
-<WRAP centeralign> Figure 12 </WRAP>
+<WRAP centeralign> Figure 23 </WRAP>
-How would you modify the values of R<sub>2</sub> and R<sub>4</sub> in version 2 ( figure 6 ) to produce a stabilized 1.0 volt output?
+How would you modify the values of R<sub>2</sub> and R<sub>4</sub> in version 2 ( figure 11 ) to produce a stabilized 1.0 volt output?
 Answer: using a potentiometer for R<sub>2</sub> the above curve was generated with R<sub>2</sub> = 5.55KΩ and R<sub>4</sub> = 69.8Ω.
+<WRAP round download>
+**Resources:**
+  * Fritzing files: [[ https://minhaskamal.github.io/DownGit/#/home?url=https://github.com/analogdevicesinc/education_tools/tree/master/m2k/fritzing/bjt_zero_gain_amp_bb | bjt_zero_gain_amp_bb]]
+  * LTspice files: [[ https://minhaskamal.github.io/DownGit/#/home?url=https://github.com/analogdevicesinc/education_tools/tree/master/m2k/ltspice/bjt_zero_gain_amp_ltspice | bjt_zero_gain_amp_ltspice]]
+</WRAP>
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