The resolution of a Digital-to-Analog Converter (DAC) determines the smallest change in analog output voltage that can be produced for a one-bit change in the digital input.
A higher DAC resolution provides:
An open-loop differential amplifier amplifies the difference between two input voltages without using feedback.
Input is not applied only to the inverting terminal.Input is not applied only to the non-inverting terminal.Output is not always zero.The output is determined by the differential input voltage.
The high-frequency gain of a Common Emitter amplifier is mainly affected by:
Also known as Miller capacitance.Effects:
Effects:
These capacitances create a low-pass filtering effect which reduces amplifier gain at high frequencies.
| Feature | Collector–Base Junction Capacitance (Ccb) | Emitter–Base Junction Capacitance (Ceb) |
|---|---|---|
| Other Name | Miller Capacitance | Input Junction Capacitance |
| Location | Between Collector and Base | Between Emitter and Base |
| Nature | Reverse-biased junction capacitance | Forward-biased junction capacitance |
| Main Effect | Creates a feedback path between output and input | Affects the input circuit |
| Impact on Gain | Reduces gain at high frequencies | Indirectly affects signal amplification |
| Impact on Input Signal | Minor direct effect | Reduces input signal amplitude at high frequencies |
| Impact on Input Impedance | Little direct effect | Influences input impedance |
| Frequency Response | Limits high-frequency performance due to Miller effect | Limits high-frequency response at input |
| Role in Transistor | Causes feedback from collector to base | Stores charge in emitter-base junction |
| Practical Concern | Miller effect increases effective input capacitance | Slows response to high-frequency input signals |
A Hartley oscillator is an LC oscillator employing inductive feedback.
These components form a resonant tank circuit.
Works on the principle of parallel resonance.
An RC Phase Shift Oscillator uses an amplifier and RC network to generate sinusoidal oscillations.
For sustained oscillations:
Three RC sections provide:180° phase shiftAmplifier provides:180° phase shiftTotal:360° phase shift
Minimum amplifier gain:29
f = 1 / (2πRC√6)
A voltage-series feedback amplifier samples output voltage and feeds it back in series with the input.
Acts as a:Voltage-Controlled Voltage Source (VCVS)
Non-inverting OP-AMP
It is not known as a transconductance amplifier.
In a non-inverting OP-AMP:
The IC 7905 belongs to the 79XX negative voltage regulator family.
7905 → -5 VSimilarly:
The IC 723 is a versatile voltage regulator used for positive and negative voltage regulation.
2 V to 37 V
Up to 150 mA
A bridge rectifier is a full-wave rectifier using four diodes arranged in bridge configuration.
PIV is the maximum reverse voltage a diode can withstand.
For a bridge rectifier:PIV per diode = Peak input voltage
Ripple factor indicates the amount of AC content present in the rectified output.
| Rectifier | Ripple Factor |
|---|---|
| Half-Wave Rectifier | Higher |
| Full-Wave Rectifier | Lower |
A Half-Wave Rectifier has more than twice the ripple factor of a Full-Wave Rectifier.
When a diode is forward biased:
Current conduction occurs primarily due to majority carriers.The statement that heavy current flow occurs because of minority carriers is incorrect.
A Zener diode operates in reverse breakdown region and maintains nearly constant voltage.
The breakdown voltage changes according to the temperature coefficient.
Forward bias behaves like a short circuit.Reverse bias behaves like a resistor.
A PLL is an electronic control system that synchronizes an oscillator with an input signal.
Removes high-frequency noise from phase detector output.
Controlled by PLL filter characteristics.
Primarily determined by:
Therefore:
A Raised Cosine Filter is used to reduce Inter-Symbol Interference (ISI).
β lies between:0 ≤ β ≤ 1
β = 0Ideal brick-wall responseβ = 1Maximum excess bandwidth
BW = Rs(1 + β)/2where Rs is the symbol rate.
Sinc pulse shaping is used for ideal Nyquist transmission.
A sinc function is obtained as the inverse Fourier transform of a rectangular frequency response.Therefore:Sinc pulse shaping is derived from a rectangular function.
A Cathode Ray Tube Oscilloscope displays electrical signals as voltage versus time waveforms.
Vertical deflection is proportional to:Amplitude of the input signalA higher input amplitude produces greater vertical movement of the electron beam.
The CRT visually displays electrical waveforms.It achieves this through:
The graticule provides a reference scale for waveform measurements.
Time delay is measured by:
Sensitivity refers to the ability of a relay to detect and respond to very small fault currents.A highly sensitive relay can operate even for minor fault conditions.
A Zener diode has a breakdown voltage of 7 V at 300 K and a temperature coefficient of 2.3 mV/°C. Determine the breakdown voltage at 400 K.
Temperature rise:ΔT = 400 − 300 = 100°CVoltage change:ΔVz = 2.3 × 100 = 230 mVΔVz = 0.230 VNew breakdown voltage:Vz = 7 + 0.230Vz = 7.23 V
Vz = 7.23 V
Input impedance without feedback = 5 kΩOutput impedance without feedback = 10 kΩFeedback factor:Aβ = 19Find input and output impedance with feedback.
Input impedance:Rif = Ri(1 + Aβ)Rif = 5 × 20Rif = 100 kΩOutput impedance:Rof = Ro/(1 + Aβ)Rof = 10/20Rof = 0.5 kΩ
Input impedance = 100 kΩOutput impedance = 0.5 kΩ
A special diode has:
Load resistance = 1 kΩInput square wave:+4 V and −4 VFind output voltage during reverse bias.
Total resistance:1 kΩ + 1 kΩ = 2 kΩUsing voltage division:Output voltage:Vo = (-4) × (1/2)Vo = -2 V
Vo = -2 V
A bridge rectifier is supplied by:24 sin(ωt) VFind PIV of each diode.
Peak voltage:Vp = 24 VFor bridge rectifier:PIV = Vp
PIV = 24 V
Open-loop gain:AOL = 10⁵Input voltage:Vin = 100 mVSupply:±15 VFind output voltage.
Theoretical output:Vo = AOL × VinVo = 10⁵ × 0.1Vo = 10000 VSince output cannot exceed supply limits,Vo = +15 V
Output voltage = +15 V