3- laboratory work investigation of uv amplifier circuit made in bt. The purpose of the work

Description of the model
The model uses a germanium, low-power, low-frequency MP 42 transistor. From its parameters the operating voltage U = (30..50) V, the collector capacity S _K = 30 pF, the maximum power R _MAX = 200 mW.
The parameters of the other elements of the scheme are as follows:
R1 = 1 kOhm, R2 = 11 kOhm, R3 = 5.1 kOhm, R4 = 3.6 kOhm, R5 = 3.6 kOhm, R6 = 47 kOhm, R7 = 20 Ohm, R8 = 510 Ohm, R9 = 3.6 kOhm, R10 = 10kOhm, S ₁ = S ₂ = S ₃ = 20 mkF.
Procedure:
Connect the model to the mains. Prepare a standard signal generator (SSG) and a variable voltage meter (millivoltmeter) with high input resistance.
3. Study the UV connected circuit
3.1. Assemble the commonly connected amplifier circuit of the transistor base. To do this, bring the connectors to the positions shown in the table. In case 15 of the connector U12-15 is connected to the circuit as a resistor load R10 = 10 kOhm R _Yu = R10 = 10 kOhm

Business paragraph	Connector condition					Checkpoint	Introduction to the scheme
	U1-2	U3-4	U5-6	U7-8	U12-15
3.1-3.3	2	4	5	7	15	3		introduction 1

2. 
   Repeat the measurements according to paragraphs 1.2-1.9.
   
3. 
   Connect a voltmeter and oscilloscope to the control points at the top of the model surface.
   
4. 
   Adjust the voltage of the supply point G1 to 6V by observing the input point potential N3 using another instrument that measures the constant voltage of the open oscilloscope YOAI.
   
5. 
   Determine the sOAinic state parameters of the transistor by connecting the AC voltage measuring instrument to control points N4, N5, N2. Given the measured potentials of the control points and the values of the resistors R4 = 3.6 kOhm, R5 = 3.6 kOhm, find the tOAs of the collector, emitter and base sOA.
   

Business paragraph	Connector condition					Checkpoint	Introduction to the scheme
	U1-2	U3-4	U5-6	U7-8	U12-15
3.5	2	4	5	7	15	2/4/5		introduction 1

3.6. Find the voltage gain K _{U of the circuit.} To do this, transmit a 2 mHz 30 mV signal from a sinusoidal generator to point "input N2" of the circuit. The input voltage is measured between the zero potential bus and the control point N2. When measuring the output voltage, it is recommended to connect the voltmeter to control point N7.

Business paragraph	Connector condition					Checkpoint	Introduction to the scheme
	U1-2	U3-4	U5-6	U7-8	U12-15
3.5-3.8	2	4	5	7	14	7		introduction 1

3.7. Measure the frequency response K _U (f) of the voltage gain. To do this, keep the amplitude of the input voltage unchanged (approximately 30 mV), change its frequency, and measure the output voltage at control point N7. It is recommended to perform measurements at values of test signals 10 Gts, 100 Gts, 1 kGts, 10 kGts, 100 kGts, 1 mHz.

3.8. At a frequency of 2 kHz, measure the amplitude characteristic of the circuit U _CHIQ = f (U _KIR ) . It is recommended to change the input signal voltage in the range of 10..300 mV.
3.9. Determine the upper limit of the amplifier phase dynamic range. To do this, observe the oscillogram of the output voltage and determine at what value of the input signal nonlinear distortions occur.
3.10. When the input voltage is 30 mV and the frequency is 2 kHz, connect the resistors R7 = 20 Ohm, R8 = 510 Ohm, R9 = 3.6 kOhm, R10 = 10 kOhm to the output of the amplifier cascade alternately using connector U12-15, and its load characteristics Measure K _U ( R _Yu ).

Business paragraph	Connector condition						Checkpoint		Introduction to the scheme
	U1-2	U3-4	U5-6	U7-8	U12-15
3.9	2	4	5	7	12..15	7		introduction 1

3.11. Repeat the measurements according to points 4,5,7,8,9 when the supply source voltage is 9 and 12V.

4. Processing of experimental results
4.1. Using the results of measuring the constant voltage at the control points, determine the sOAinlik mode of the transistor at each of the recommended values of the supply source voltage. Determine the parameters of the transistor in each of the given sOAinlik cases.
4.2. Transistor 4.1. determine the voltage ( K _U ), power ( K _R ) amplification coefficients of the amplifier cascade, input and output resistances in VA, based on the parameters defined in paragraph and certain parameters of other elements of the circuit .
4.3. Compare the different connection diagrams of the transistor based on the results of experiments and calculations.


Content of the report:
- parameters of the studied transistor.
- Schematic diagram of the laboratory work.
- for each stage of the work performed - the name of the stage and the results obtained (in the form of tables, graphs and oscillograms).
- A brief summary of the results obtained.



Scheme assembled on the basis of a multisim program.


Control questions

1. 
   What are the differences (schemes, parameters and characteristics) between UV, UE and UK amplifier cascades?
   
2. 
   Draw an equivalent circuit of the transistor, the transistor amplifier stage.
   
3. 
   Measure (determine) the input and output resistance of the amplifier, voltage, tOA, and power gain.
   
4. 
   Causes of signal distortion in the transistor amplifier stage.
   
5. 
   How do you understand the cutoff frequency?