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Why voltage gain decreases at high frequency in case of a transformer coupled amplifier?
Depends on the elements used in the circuit.1.At Low frequency: The coupling capacitors are used to isolate the AC input and output from DC bias conditions for active devices. These capacitors with the input and output impedance of the active device act as a high pass RC filter, hence the gain falls.2. At High Frequency: The frequency is high, but not as high as the microwave frequencies. There are two reasonsa>The capacitance of connecting wires are connected in parallel the i/p and o/p. When a capacitor is connected in parallel it acts as low pass filter, hence the voltage gain falls. This is when the frequency is high but not high as microwave frequencies.b> The parasitic capacitance's of the active device are connected in parallel with the i/p and o/p terminals. They along with the device impedances act as low pass filter.
What is pre-emphasis and de-emphasis in FM?
In FM, the effect of noise is more on higher frequencies when compared with low frequencies. Therefore in order to have high signal-to-noise ratio(low noise), the high frequencies are amplified at the transmitter side and for compensation deemphasis(decreasing the amplitude of those boosted frequencies ) is done at receiver.
How do the parasitic capacitance limit the high frequency operation of an integrated circuit?
Parasitic capacitance is the inherent capacitance between different planes of metal in a circuit. The main problem is that capacitors look like shorts to high frequencies, which can then simulate grounding shorts, line linkage, feedback paths and other generally undesirable features in the circuit. In particular, in ICs, the problem is 'crosstalk', wherein signals in one part of the IC induce a signal through capacitive coupling in another part of the circuit.
How is the resistor behaved at high frequency?
The major problem with resistors at high frequencies is for wire-wound (power) resistors, that will act as inductors at high frequencies. In addition, very small resistors, like chip resistors, can also exhibit capacitive effects. Special high frequency resistors are designed to offset these effect.[1]
What is effect of internal capacitance of transistor and resistor on propagation delay?
Internal capacitance of transistor increases propagation delay.Because charging and discharging of these capacitors will take more time which is not favourable.So always try to select transistors with minimum capacitance.
Why ordinary diodes dont work properly At high frequencies?
Because of stray capacitance. At very high frequencies, the inter-electrode capacitance has a low enough impedance that the diode no longer cuts off when reverse-biased, there is still significant conduction via capacitive coupling. High-frequency diodes are constructed so as to minimize this capacitance.
What is the stray capacitor?
Stray capacitance is undesired capacitance. Any electronic component (wires, resistors, etc.) has SOME capacitance; at high frequencies, this can become significant, becoming a problem for circuit design.
What is the effect of capacitance in high frequency circuits and how it is getting added?
First, capacitance is the resistance of something to a change in voltage. And capacitance exists anywhere there is a conductor that is insulated from another conductor. With that definition, anything has capacitance. And that's correct. It is also the key to understanding the capacitance in high frequency (radio frequency or RF) circuits. The fact that a circuit had conductive pathways and component leads and such means that there is a lot of little bits of capacitance distributed around the circuit. The capacitance is already there; it isn't "added" later as might be inferred. Normally, this bit of capacitance isn't a problem. But at higher and higher frequencies, it is. Remember that the higher the frequency of an AC signal, the better it goes through a given cap. So at higher and higher frequencies, the distributed capacitance in the circuit "shorts the signal to ground" and takes it out of the circuit. The RF is said to be coupled out of the circuit through the distributed capacitance in that circuit. The higher the frequency a given circuit is asked to deal with, the more signal will be lost to this effect. It's just that simple. Design considerations and proper component selection minimize the distributed capacitance in a circuit.
What is the effect if capacitance in transmission line is high?
higher phase shift lower impedance
What is the effect of inductance in high frequency circuits?
Inductive reactance is proportional to frequency... XL = 2 pi f L ... so, the higher the frequency, the higher the reactance. At a sufficiently high frequency, the inductor would appear to be an open circuit. Note, however, that at very high frequencies, parasitic capacitance becomes a factor.
Why h parameter are not used for transistor mode at high frequency?
finding h parameters involves open and short circuits which is difficult to obtain at high frequencies due to stray inductance and capacitance
What is the effect of inductance in the circuit?
Inductive reactance is proportional to frequency... XL = 2 pi f L ... so, the higher the frequency, the higher the reactance. At a sufficiently high frequency, the inductor would appear to be an open circuit. Note, however, that at very high frequencies, parasitic capacitance becomes a factor.
Why voltage gain decreases at high frequency in case of a transformer coupled amplifier?
Depends on the elements used in the circuit.1.At Low frequency: The coupling capacitors are used to isolate the AC input and output from DC bias conditions for active devices. These capacitors with the input and output impedance of the active device act as a high pass RC filter, hence the gain falls.2. At High Frequency: The frequency is high, but not as high as the microwave frequencies. There are two reasonsa>The capacitance of connecting wires are connected in parallel the i/p and o/p. When a capacitor is connected in parallel it acts as low pass filter, hence the voltage gain falls. This is when the frequency is high but not high as microwave frequencies.b> The parasitic capacitance's of the active device are connected in parallel with the i/p and o/p terminals. They along with the device impedances act as low pass filter.
Why RC oscillators are not used for high frequencies?
The "C" in RC is capacitance, and at high frequencies, the C will shunt the signal more than at lower frequencies. The loss through the cap will climb right along with frequency. And as the cap's performance goes down, so, too, does the circuit performance. RC oscillator performance is far from linear at the top of the frequency range.
Does lead length matter in capacitance of a capacitor?
In general the length of the leads contributes only a negligible amount to the capacitance of a capacitor. However at high enough frequencies excessive lead length can contribute an undesirable amount of parasitic inductive reactance, causing problems in circuit operation.
What is the type of capacitance effect exhibited in P-N junction when it is reverse biased?
1. Transition capacitance 2. Diffusion capacitance 3. Space charge capacitance 4. Drift capacitance
What is the difference between capacitance and stray capacitance?
Capacitance is an ability to store an electric charge. "If we consider two same conductors as capacitor,the capacitance will be small even the conductors are close together for long time." this effect is called Stray Capacitance.
