Discharging a Capacitor
Charging a Capacitor
Electric FluxClosely Related Articles
Op-amp | Working Principle of Op-amp
Amplifier Gain | Decibel or dB Gain
Integrated Circuits | Types of IC
Regulated Power Supply
Laser | Types and Components of Laser
Mobility of Charge Carrier
What are Photo Electrons?
Electron volt or eV
Energy Quanta | Development of Quantum Physics
Heisenberg Uncertainty Principle
Schrodinger Wave Equation and Wave Function
Cyclotron Basic Construction and Working Principle
Sinusoidal Wave Signal
Common Emitter Amplifier
RC Coupled Amplifier
Wave Particle Duality Principle
Vacuum Diode History Working Principle and Types of Vacuum Diode
PN Junction Diode and its Characteristics
Diode | Working and Types of Diode
Half Wave Diode Rectifier
Full Wave Diode Rectifier
Diode Bridge Rectifier
What is Zener Diode?
Application of Zener Diode
LED or Light Emitting Diode
PIN Photodiode | Avalanche Photodiode
Tunnel Diode and its Applications
Diode Current Equation
Reverse Recovery Time of Diode
MOSFET | Working Principle of p-channel n-channel MOSFET
MOS Capacitor | MOS Capacitance C V Curve
Applications of MOSFET
MOSFET as a Switch
Half Wave Rectifiers
Full Wave Rectifiers
Theory of Semiconductor
Energy Bands of Silicon
Impurities in Semiconductor
Conductivity of Semiconductor
Current Density in Metal and Semiconductor
Intrinsic Silicon and Extrinsic Silicon
P Type Semiconductor
N Type Semiconductor
P N Junction
Bias of P N Junction
Gallium Arsenide Semiconductor
Types of Transistors
Bipolar Junction Transistor
Biasing of BJT
Current Components in a Transistor
Transistor Manufacturing Techniques
Applications of BJT
Transistor as a Switch
Transistor as an Amplifier
n-channel JFET and p-channel JFET
Applications of FET
RC Coupled Amplifier
Further, the coupling capacitor CC also increases the stability of the network as it blocks the DC while offers a low resistance path to the AC signals, thereby preventing the DC bias conditions of one stage affecting the other. In addition, in this circuit, the voltage drop across the collector-emitter terminal is chosen to be 50% of the supply voltage VCC inorder to ensure appropriate biasing point. In this kind of amplifier, the input signal applied at the base of the transistor in stage 1 (Q1) is amplified and appears at its collector terminal with a phase-shift of 180o. The AC component of this signal is coupled to the second stage of the RC coupled amplifier through the coupling capacitor CC and thus appears as an input at the base of the second transistor Q2. This is further amplified and is passed-on as an output of the second stage and is available at the collector terminal of Q2 after being shift by 180o in its phase. This means that the output of the second stage will be 360o out-of-phase with respect to the input, which inturn indicates that the phase of the input signal and the phase of the output signal obtained at stage II will be identical. Further it is to be noted that the cascading of individual amplifier stages increases the gain of the overall circuit as the net gain will be the product of the gain offered by the individual stages. However in real scenario, the net gain will be slightly less than this, due to the loading effect. In addition, it is important to note that by following the pattern exhibited by Figure 1, one can cascade any number of common emitter amplifiers but by keeping in mind that when the number of stages are even, the output will be in-phase with the input while if the number of stages are odd, then the output and the input will be out-of-phase. The frequency response of a RC coupled amplifier (a curve of amplifier's gain v/s frequency), shown by Figure 2, indicates that the gain of the amplifier is constant over a wide range of mid-frequencies while it decreases considerably both at low and high frequencies. This is because, at low frequencies, the reactance of coupling capacitor CC is high which causes a small part of the signal to couple from one stage to the other. Moreover for the same case, even the reactance of the emitter capacitor CE will be high due to which it fails to shunt the emitter resistor RE effectively which inturn reduces the voltage gain. On the other hand, at high frequencies, the reactance of CC will be low which causes it to behave like a short circuit. This results in an increase in the loading effect of the next stage and thus reduces the voltage gain. In addition to this, for this case, the capacitive reactance of the base-emitter junction will be low. This results in a reduced voltage gain as it causes the base current to increase which inturn decreases the current amplification factor β. However, in mid-frequency range, as the frequency increases, the reactance of CC goes on decreasing which would lead to the increase in gain if not compensated by the fact that the reduction in reactance leads to an increase in the loading effect. Due to this reason, the gain of the amplifier remains uniform/constant throughout the mid-frequency band.
Advantages of RC Coupled Amplifier
- Cheap, economical and compact as it uses only resistors and capacitors.
- Offers a constant gain over a wide frequency band.
Disadvantages of RC Coupled Amplifier
- Unsuitable for low-frequency amplification.
- Low voltage and power gain as the effective load resistance (and hence the gain) is reduced due to the fact that the input of each stage presents a low resistance to its next stage.
- Moisture-sensitive, making them noisy as time elapses.
- Poor impedance matching as it has the output impedance several times larger than the device at its end-terminal (for example, a speaker in the case of a public address system).
- Narrow bandwidth when compared to JFET amplifier.
Applications of RC Coupled Amplifier
- RF Communications.
- Optical Fiber Communications.
- Public address systems as pre-amplifiers.
- Radio or TV Receivers as small signal amplifiers.
Closely Related Articles Op-amp | Working Principle of Op-ampAmplifier Gain | Decibel or dB GainIntegrated Circuits | Types of ICRegulated Power SupplyLaser | Types and Components of LaserWork FunctionMobility of Charge CarrierWhat are Photo Electrons? Electron volt or eVEnergy Quanta | Development of Quantum Physics Schottky EffectHeisenberg Uncertainty PrincipleSchrodinger Wave Equation and Wave FunctionCyclotron Basic Construction and Working PrincipleSinusoidal Wave SignalCommon Emitter AmplifierDifferential AmplifierWave Particle Duality PrincipleSpace ChargeInverting AmplifierMore Related Articles Vacuum Diode History Working Principle and Types of Vacuum DiodePN Junction Diode and its CharacteristicsDiode | Working and Types of DiodeDiode CharacteristicsHalf Wave Diode RectifierFull Wave Diode RectifierDiode Bridge RectifierWhat is Zener Diode?Application of Zener DiodeLED or Light Emitting DiodePIN Photodiode | Avalanche PhotodiodeTunnel Diode and its ApplicationsGUNN DiodeVaractor DiodeLaser DiodeSchottky DiodePower DiodesDiode ResistanceDiode Current EquationIdeal DiodeReverse Recovery Time of DiodeDiode TestingMOSFET | Working Principle of p-channel n-channel MOSFETMOSFET CircuitsMOS Capacitor | MOS Capacitance C V CurveApplications of MOSFETMOSFET as a SwitchMOSFET CharacteristicsPower MOSFETHalf Wave RectifiersFull Wave RectifiersBridge RectifiersClamping CircuitTheory of SemiconductorIntrinsic SemiconductorExtrinsic SemiconductorsEnergy Bands of SiliconDonor and Acceptor Impurities in Semiconductor Conductivity of SemiconductorCurrent Density in Metal and Semiconductor Intrinsic Silicon and Extrinsic SiliconP Type SemiconductorN Type SemiconductorP N Junction Theory Behind P N JunctionForward and Reverse Bias of P N JunctionZener BreakdownAvalanche BreakdownHall Effect Applications of Hall EffectGallium Arsenide SemiconductorSilicon SemiconductorTypes of TransistorsBipolar Junction Transistor or BJTBiasing of Bipolar Junction Transistor or BJTTransistor BiasingTransistor CharacteristicsCurrent Components in a TransistorTransistor Manufacturing TechniquesApplications of Bipolar Junction Transistor or BJT | History of BJTTransistor as a SwitchTransistor as an AmplifierJFET or Junction Field Effect Transistorn-channel JFET and p-channel JFETApplications of Field Effect TransistorDIAC Construction Operation and Applications of DIACTRIAC Construction Operation and Applications of TRIACPhototransistorNew Articles Ring CounterDischarging a CapacitorCharging a CapacitorElectric PotentialParity GeneratorElectric Flux