Electronics
Table of Contents
1. Voltage Clamping
1.1. Diode
The circuit can be hooked up to the desired voltage via diode, allowing the current to flow when the voltage gets out of the bound regulating the voltage within the original state.
2. Coupling
2.1. AC Coupling
A capacitor is used to admit selectively the AC signal. The output portion has to be hooked up to the desired bias with a resistor.
3. Filter
3.1. High Frequency Filter
A high frequency can be filtered by:
- passing the signal through a capacitor
- hooking to the ground with a capacitor (AC ground)
3.2. Low Frequency Filter
3.3. Band Filter
4. Pulse-Width Modulation
- PWM
It generates repeating pulses that averages to various voltage. This can be used to control the power cosumed by an electronics, controlling various parameters.
5. Amplifier
5.1. Classes
5.1.1. Class A
It is one biased transistor. Which allows large idle current, making it inefficient.
5.1.2. Class B
It combines NPN and PNP transistors, so that it can trigger regardless of the sign of the signal.
It suffers from zero-crossing distortion, due to the threshold volatage for each transistors.
5.1.3. Class AB
Class B, but the signal is biased slightly to remove the distortion.
5.1.4. Class D
It compares the analog signal with the steady triangular wave, and outputs according to the result of the comparison.
6. Delay Effect
It samples the signal in a capacitor using MOSFET switch, and uses bucket-brigade device (BBD) to delay the signal, and lastly reconstruct the signal.
6.1. Flanger
A repeater with minute delay.
7. Slew Rate
It is the maximum rate of change in voltage or current.
\[ \mathrm{SR} = \mathrm{max}\left| \frac{dv_{\rm out}(t)}{dt} \right| \]
8. Common Mode Rejection Ratio
The rate of response of a differential operator to a identical input.
9. Impedance
In an AC (altenating current) circuit, there is phase information on top of amplitude information of DC.
The phase and amplitude are effectively represented by argument and modulus of complex number. The voltage \( v(t) \) and current \( i(t) \) are decomposed into pure sinusoidal wave, and the time-independent phasor that represents the relative phase and amplitude information. \[ v = V e^{i\omega t} \]
The impedance \( Z \) is the ratio of voltage to current: \[ Z = \frac{v}{i}. \] Positive argument (< pi) means the voltage precedes current (if \( \omega \) is positive).