- 10 Determine Output Capacitor Value The Output Capacitor Value Is Generally Chosen To Be Equal The Circuit Resistance A 1 (50.27 KiB) Viewed 55 times
10) Determine output capacitor value The output capacitor value is generally chosen to be equal the circuit resistance at the lowest frequency of operation. The circuit resistance is the emitter follower output resistance plus the resistance of the load, 6 of 6 PROBLEM STATEMENT Design a common emitter amplifier (see Figure 1). Use: a) an NPN transistor with DC current gain between 100 and 200. h) a supply voltage between 15V and 30V. c) an input signal with frequency of 100Mhz d) a load of 100012 Also: a) use Multisim to simulate the operation of that amplifier about a properly chosen Q point. Observe the voltages, currents, and gains etc b) Shift the Q point close to the top of the load line then use Multisim to simulate the operation of that amplifier. Observe the voltages, currents, and gains ctc c) Shift the Q point close to the bottom of the load line then use Multisim to simulate the operation of that amplifier. Observe the voltages, currents, and gains etc d) Submit a lab report,
OBJECTIVE Design a common emitter amplifier and use Multisim simulate the operation of the amplifier with a properly chosen Q point and improperly chosen Q points. PRE LAB Amplifiers are used to increase the voltage and current of a weak signal to desired level. There are two types of amplifiers. They are given below. 1) DC to DC Amplifier
3) Choose a suitable supply voltage and operating frequency 4) Calculating the value of the collector resistor ine the current flow required to adequately drive the following stage. Then choose 5 of 6 tor resistor voltage drop that is approximately half the supply voltage to enable wywar excursions of the output signal up and down the load line. The collector resistor value can then be calculated from the voltage and current 5) Calculating the value of the emitter resistor Generally, it is recommended that the voltage drop across the cmitter resistor is 10% of the supply voltage (A rule of thumb). This gives a good level of DC stability to the circuit. Calculate the emitter resistor value from the knowledge of the collector current (effectively the same as the emitter current) and the emitter resistor voltage drop. 6) Determine base current 7) Determine the base voltage - Use two resistors to implement a voltage divider. 8) Determine base resistor 9) Determine the value of the emitter bypass capacitor The voltage gain of the circuit without a capacitor across the emitter resistor is approximately RC/RE. To increase the gain of AC signals, the emitter resistor bypass capacitor is added. This should be calculated to have a reactance equal to RC at the lowest frequency of operation. The formula to calculate bypass capacitor is C-(1/(2(XC)). NB: RC-Resistance of the collector resistor, RE-Resistance of the emitter resistor; XC- Reactance of the emitter capacitance. 10) Determine output capacitor value The output capacitor value is generally chosen to be equal the circuit resistance at the lowest frequency of operation. The circuit resistance is the emitter follower output resistance plus the resistance of the load, PROBLEM STATEMENT