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Figure from:Laboratory Guide for Electronics 1: Basic Components

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In measuring the FET characteristics in the previous experiment, two power supplies were used. For practical applications a single power supply is preferable. In the self bias diagram above, the voltage rise, Vpp across the power supply equals the voltage drop across the transistor and the two resistors, Rg and Rp. Since there is no current in the gate circuit, there is no voltage drop across Rg . Therefore Ves just equals the voltage drop across Rs. (Rg could be omitted for biasing, but it is needed when a signal is applied to the gate).

Figure 43 In measuring the FET characteristics in the previous experiment, two power supplies were used. For practical applications a single power supply is preferable. In the self bias diagram above, the voltage rise, Vpp across the power supply equals the voltage drop across the transistor and the two resistors, Rg and Rp. Since there is no current in the gate circuit, there is no voltage drop across Rg . Therefore Ves just equals the voltage drop across Rs. (Rg could be omitted for biasing, but it is needed when a signal is applied to the gate).

Related Figures (74)

It is convenient to superimpose on the diode graph The line of the inverted resistor graph is the load line, and the point of intersection is the Q-point. At the Q-point the resistor and diode currents are the same; the diode voltage is Va, the resistor voltage s Vs-Vgqg so their total is Vg as expected. This oad line technique for a series combinations of two elements across a fixed voltage will occur again in the analysis of transistors.
It is convenient to superimpose on the diode graph The line of the inverted resistor graph is the load line, and the point of intersection is the Q-point. At the Q-point the resistor and diode currents are the same; the diode voltage is Va, the resistor voltage s Vs-Vgqg so their total is Vg as expected. This oad line technique for a series combinations of two elements across a fixed voltage will occur again in the analysis of transistors.
Data Sheet: Electronics | Name:
Data Sheet: Electronics | Name:
As shown, the zener diode is placed in parallel with the load so for regulation we select a zener with Vz equal to the desired load voltage, V,_. But to provide regulation, the zener current, Iz, must be greater than zero so |, must be sufficient to turn “on” the zener and provide the desired voltage drop across the load.
As shown, the zener diode is placed in parallel with the load so for regulation we select a zener with Vz equal to the desired load voltage, V,_. But to provide regulation, the zener current, Iz, must be greater than zero so |, must be sufficient to turn “on” the zener and provide the desired voltage drop across the load.
In practice a is taken as 1, while B will vary from transistor to transistor. Transistor characteristics refer to a graphical presentation of the relationships between these variables. For each configuration we consider separately the input (/nput voltage and current) and output (output voltage and current) characteristics. However, since the output (emitter or collector) current is controlled by the level on the input (base) current, a third variable is involved with the output characteristics. A complete graphical presentation of three variable would require a three-dimensional graph which is a bit hard to sketch. As a compromise output current and voltage are plotted along the Y and X axes, and separate graph lines are shown for various values of base current. The most often used display is the common emitter. Electronics | Experiment #11: BJT Characteristics Materials: Module EL1-G , two multimeters, power sur
In practice a is taken as 1, while B will vary from transistor to transistor. Transistor characteristics refer to a graphical presentation of the relationships between these variables. For each configuration we consider separately the input (/nput voltage and current) and output (output voltage and current) characteristics. However, since the output (emitter or collector) current is controlled by the level on the input (base) current, a third variable is involved with the output characteristics. A complete graphical presentation of three variable would require a three-dimensional graph which is a bit hard to sketch. As a compromise output current and voltage are plotted along the Y and X axes, and separate graph lines are shown for various values of base current. The most often used display is the common emitter. Electronics | Experiment #11: BJT Characteristics Materials: Module EL1-G , two multimeters, power sur
resulting graph line is quite similar to that of a forward-biased diode. The ratio Vee / Ip is the
resulting graph line is quite similar to that of a forward-biased diode. The ratio Vee / Ip is the
For any transistor, the “common emitter characteristics’ reflect the relation between the base, emitter and collector currents and voltages at the time of manufacture, although the actual values do vary from unit to unit. In use, the transistor is incorporated into an externai circuit, involving fixed DC voltages and currents, as well as time-varying AC voltages and currents. The Principle of Superposition allows us to treat separately the DC and the AC areas. Biasing refers to the DC area
For any transistor, the “common emitter characteristics’ reflect the relation between the base, emitter and collector currents and voltages at the time of manufacture, although the actual values do vary from unit to unit. In use, the transistor is incorporated into an externai circuit, involving fixed DC voltages and currents, as well as time-varying AC voltages and currents. The Principle of Superposition allows us to treat separately the DC and the AC areas. Biasing refers to the DC area
3: Repeat step #2 for: Vec = 12.00 volts, Ie = 25.0 mA, Veg = 5.00.
3: Repeat step #2 for: Vec = 12.00 volts, Ie = 25.0 mA, Veg = 5.00.
For the input loop we obtain:
For the input loop we obtain:
EI€CtIrONniCs | Experiment #15: BJT Biasing: Common Base Rimtayvimtlas AARBAAZ IR Cl 4 Ld ob wilt mRntarrn nniseyp nmiienrh, OQ wurlt rn: 2: Use these values with Module EL-1-H, and measure the actual values of Vee and Vege in the circuit. With these corrected values again solve the equations for Re and Re.
EI€CtIrONniCs | Experiment #15: BJT Biasing: Common Base Rimtayvimtlas AARBAAZ IR Cl 4 Ld ob wilt mRntarrn nniseyp nmiienrh, OQ wurlt rn: 2: Use these values with Module EL-1-H, and measure the actual values of Vee and Vege in the circuit. With these corrected values again solve the equations for Re and Re.
1: Set Vec = 10.0 volt. Select the Q-point as : Ic = 10.00 mA, Vce = 4.00 volts and assume Vege = 0.45 volts.
1: Set Vec = 10.0 volt. Select the Q-point as : Ic = 10.00 mA, Vce = 4.00 volts and assume Vege = 0.45 volts.
Notice the polarity of the battery in the input circuit. The gate-source junction is reverse biased so ther is no gate current. As with the BUT, we specify an operating, or Q, point by assigning definite values to Vps and Ips. The drain-source voltage term, Vps, does not appear in the Shockley equation for Ips, suggesting that the drain-source current is independent of the drain-source voltage! Over a wide voltage range this is approximately true. The bipolar junction transistor, BJT, is a current-controlled device; the collector-emitter current is directly proportional to the base-emitter current (the proportionality constant is B). The field-effect transistor, FET, is a voltage-controlled device; the source-drain current is controlled by the gate-source voltage (the proportionality factor is not linear). The source-drain current, Ips, can be expressed in terms of the variable gate-source voltage, Ves, and two constants: Ipss, the source-drain current with Vgs=0, and Vp, the minimum value of V¢s that sets Ips=0. Notice that on a graph of source-drain current ( vertical ) against gate-source voltage (horizontal ), each of these constants lies on a separate coordinate axis. The graph line joining these two points is nota straight line, but a segment of a parabola. The Shockley equation expresses this relation:
Notice the polarity of the battery in the input circuit. The gate-source junction is reverse biased so ther is no gate current. As with the BUT, we specify an operating, or Q, point by assigning definite values to Vps and Ips. The drain-source voltage term, Vps, does not appear in the Shockley equation for Ips, suggesting that the drain-source current is independent of the drain-source voltage! Over a wide voltage range this is approximately true. The bipolar junction transistor, BJT, is a current-controlled device; the collector-emitter current is directly proportional to the base-emitter current (the proportionality constant is B). The field-effect transistor, FET, is a voltage-controlled device; the source-drain current is controlled by the gate-source voltage (the proportionality factor is not linear). The source-drain current, Ips, can be expressed in terms of the variable gate-source voltage, Ves, and two constants: Ipss, the source-drain current with Vgs=0, and Vp, the minimum value of V¢s that sets Ips=0. Notice that on a graph of source-drain current ( vertical ) against gate-source voltage (horizontal ), each of these constants lies on a separate coordinate axis. The graph line joining these two points is nota straight line, but a segment of a parabola. The Shockley equation expresses this relation:
These three parameters are calculated for a given Q-point ( Vce, Ic). In each case we are concerned with the ratio of changes about a given value for particular quantities. To explain the method, let us select the following: Vec=12.00 V, Vce=6.00 V, Ic= 20.0 mA. These are not the only parameters that could have been selected (for a three terminal device, there are three terminal currents, and three voltages between different pairs of terminals) but they are the most common. The input and output characteristics displays the relationships between these quantities. From these characteristic curves, three additional values are derived for AC or signal values, which are quite important for transistor circuit analysis. For the BJT these are:
These three parameters are calculated for a given Q-point ( Vce, Ic). In each case we are concerned with the ratio of changes about a given value for particular quantities. To explain the method, let us select the following: Vec=12.00 V, Vce=6.00 V, Ic= 20.0 mA. These are not the only parameters that could have been selected (for a three terminal device, there are three terminal currents, and three voltages between different pairs of terminals) but they are the most common. The input and output characteristics displays the relationships between these quantities. From these characteristic curves, three additional values are derived for AC or signal values, which are quite important for transistor circuit analysis. For the BJT these are:
measured in millivolts, is numerically equal the current through it, measured in microamperes. Adjust Ry, Re or both so that the collector current, Ic, equals the prescribed 20.0 mA.
measured in millivolts, is numerically equal the current through it, measured in microamperes. Adjust Ry, Re or both so that the collector current, Ic, equals the prescribed 20.0 mA.
In many practical circuits a capacitor (50 uf ... 470 uf) is placed in parallel with the emitter resistor, Re. This does not affect the DC biasing, but for the small signal analysis this bypass capacitor effectively short-circuits the emitter resistor, so we may flake Re ~ 0. In Experiment #12 we considered the fixed bias configuration: the diagram there is reproduced below:
In many practical circuits a capacitor (50 uf ... 470 uf) is placed in parallel with the emitter resistor, Re. This does not affect the DC biasing, but for the small signal analysis this bypass capacitor effectively short-circuits the emitter resistor, so we may flake Re ~ 0. In Experiment #12 we considered the fixed bias configuration: the diagram there is reproduced below:
6: Compute the values of Z;}, Zp, Ay and Aj using the measured values of Rp, Rc , Re, Bac and Ie. Compare these with the results of step 4 above.
6: Compute the values of Z;}, Zp, Ay and Aj using the measured values of Rp, Rc , Re, Bac and Ie. Compare these with the results of step 4 above.
In Experiment #13 we considered the voltage divider bias configuration: the diagram there is reproduced below. For small signal analysis, this circuit is similar to the emitter stabilized circuit of Experiment 21; however Rg is taken as the parallel combination of R; and Ro. The emitter may or may not be bypassed by a capacitor. Use the following values: Vec=12.00 V, Ve=2.00 V, Vce=6.00 V, Ic=20.0 mA Input Signal = 2 kHz.
In Experiment #13 we considered the voltage divider bias configuration: the diagram there is reproduced below. For small signal analysis, this circuit is similar to the emitter stabilized circuit of Experiment 21; however Rg is taken as the parallel combination of R; and Ro. The emitter may or may not be bypassed by a capacitor. Use the following values: Vec=12.00 V, Ve=2.00 V, Vce=6.00 V, Ic=20.0 mA Input Signal = 2 kHz.
In Experiment 14 we considered collector feedback biasing. We now make a_ small signal analysis of the same configuration. We may optionally bypass the emitter resistor with a large capacitor;
In Experiment 14 we considered collector feedback biasing. We now make a_ small signal analysis of the same configuration. We may optionally bypass the emitter resistor with a large capacitor;
Data Sheet: Electronics | Experiment # 2¢ BJT Small Signal: Collector Feedback Bias
Data Sheet: Electronics | Experiment # 2¢ BJT Small Signal: Collector Feedback Bias
For the BJT, § Is the ratio of the change in the output current to the change in the controlling input current ; B is dimensionless, the ratio of two currents. For the FET the counterpart of B is Gm, the ratio of the change in output current to the change in the controlling input voltage; Gm has the dimensions of reciprocal ohms or siemens, and is called transconductance. EWEGSOWE IRAE EM ENA SALA BeBe! 8 Eg: ROR Na ARS RE Jog EE Sak ER RAR yg EON EAE Ng EN, We considered the characteristics of the BJT in Experiment #11, and those oft the FET in Experiment #17. In Experiment #20 we considered the BJT small signa parameters, Bac, fo and fe. In the present experiment we consider the FET smal signal parameters, Gm and fg . The figure below displays the similarity and the differences for the two transistor types.
For the BJT, § Is the ratio of the change in the output current to the change in the controlling input current ; B is dimensionless, the ratio of two currents. For the FET the counterpart of B is Gm, the ratio of the change in output current to the change in the controlling input voltage; Gm has the dimensions of reciprocal ohms or siemens, and is called transconductance. EWEGSOWE IRAE EM ENA SALA BeBe! 8 Eg: ROR Na ARS RE Jog EE Sak ER RAR yg EON EAE Ng EN, We considered the characteristics of the BJT in Experiment #11, and those oft the FET in Experiment #17. In Experiment #20 we considered the BJT small signa parameters, Bac, fo and fe. In the present experiment we consider the FET smal signal parameters, Gm and fg . The figure below displays the similarity and the differences for the two transistor types.
In Experiments #18 and #19 we considered separately FET se/f and voltage divider bias. The DC circuits for these are repeated here.
In Experiments #18 and #19 we considered separately FET se/f and voltage divider bias. The DC circuits for these are repeated here.
1: Using the methods of Experiment # 18, determine the values for Rs, Rp and Ro to satisfy the Q-point values. Configure Module EL1-J using these values.
1: Using the methods of Experiment # 18, determine the values for Rs, Rp and Ro to satisfy the Q-point values. Configure Module EL1-J using these values.
1: Using the methods of Experiment # 18, determine the values for Rs, Rp, Ri andR to satisfy the Q-point values. Configure Module EL1-J using these values, and adjus them, if necessary, to maintain the desired Q-point..
1: Using the methods of Experiment # 18, determine the values for Rs, Rp, Ri andR to satisfy the Q-point values. Configure Module EL1-J using these values, and adjus them, if necessary, to maintain the desired Q-point..