MODULE 1 — Basic Electronics Components
1.1 Electronic Component Symbols
Hover over a symbol to see details
1.2 Comparison of Resistor Types
| Type | Material | Range | Power | Tolerance | Noise | HF Response |
|---|---|---|---|---|---|---|
| Carbon Composition | Carbon-Clay | upto 20MΩ | upto 2W | ±5% to ±20% | Low | Better |
| Carbon & Metal Film | Carbon/metal film | upto 20MΩ | > Carbon | ±1% to ±5% | High | Normal |
| Wire Wound | Wire on core | upto 100kΩ | upto 200W | ≈ ±1% | Very Low | Poor |
1.3 Comparison of Capacitor Types
Hover over a row to see structure
| Type | Dielectric (K) | Range | Voltage Rating | Polarity | Application |
|---|---|---|---|---|---|
| Paper/Polyester | Polyester (2.0) | 0.0005μF to 10μF | upto 2000V | No | AC, DC, Tuned |
| Ceramic | Ceramic (80-1200) | 3pF to 2μF | 3V to 6000V | No | Coupling, Bypass |
| Mica | Mica (3-8) | 1pF to 1μF | 500V, 40kV HF | No | Temp varying |
| Electrolyte | Al Oxide (7) | 1μF - thousands μF | 1V to 500V | Yes (+) | Filter, Coupling |
MODULE 2 — Semiconductor Fundamentals
2.1 Energy Bandgap
$$ E_g = E_c - E_v $$
$E_c$ = Cond. band, $E_v$ = Val. band
| Material | Ge | Si | GaAs |
|---|---|---|---|
| $E_{g0K}$ | 0.785 eV | 1.21 eV | 1.52 eV |
| $E_{g300K}$ | 0.72 eV | 1.1 eV | 1.42 eV |
2.2 Fermi Level
$$ F(E) = \frac{1}{1 + e^{(E - E_F)/KT}} $$
$$ E_F = \frac{E_c + E_v}{2} -
\frac{KT}{2}\ln\left(\frac{N_c}{N_v}\right) $$
2.3 Doping & Conductivity
$$ N_D + p = N_A + n \quad \text{(Neutrality)} $$
- Heavy doping (1:$10^3$) → $N^+, P^+$
- Moderate (1:$10^6$) → $N, P$
- Light (1:$10^{11}$) → $N^-, P^-$
Moderate Doping |
10^8
2.4 Mass Action Law
$$ n \cdot p = n_i^2 $$
$$ n_i = \sqrt{A_0} T^{3/2} e^{-E_g/2KT} $$
$$ \text{Minority} = \frac{n_i^2}{\text{Majority}} $$
Intrinsic Concentration at 300K:
Si: $1.5 \times 10^{10} \text{ cm}^{-3}$
Ge: $2.5 \times 10^{13} \text{ cm}^{-3}$
Si: $1.5 \times 10^{10} \text{ cm}^{-3}$
Ge: $2.5 \times 10^{13} \text{ cm}^{-3}$
2.5 Thermal Voltage (VT)
$$ V_T = \frac{KT}{q} = \frac{T}{11600} $$
$$ \frac{D_n}{\mu_n} = \frac{D_p}{\mu_p} = V_T $$
VT = 25.86 mV
2.6 Drift & Diffusion Currents
Drift (Electric Field)
$$ J_n(\text{drift}) = nq\mu_n E $$
$$ J_p(\text{drift}) = pq\mu_p E $$
Diffusion (Gradient)
$$ J_n(\text{diff}) = +qD_n\frac{dn}{dx} $$
$$ J_p(\text{diff}) = -qD_p\frac{dp}{dx} $$
E Field ➔
vs
High ➔ Low
2.7 Mobility (μ)
$$ \mu = \frac{v_d}{E} \quad [m^2/V\cdot s] $$
$$ \mu \propto T^{-m} $$
e⁻ mobility ($cm^2/Vs$):
Ge: 3800 | Si: 1300 | GaAs: 8500
Ge: 3800 | Si: 1300 | GaAs: 8500
2.8 Hall Effect
$$ V_H = \frac{BI}{\rho W} = R_H \frac{BI}{W} $$
$$ R_H = \frac{1}{nq} \text{ (n-type)} $$
MODULE 3 — PN Junction Diode
3.1 PN Junction Formation & Depletion Layer
$$ W = \{\{2\ V_0}{q}
\(\{N_A + N_D}{N_A \ N_D}\)} $$
$$ V_0 = V_T \\(\{N_A N_D}{n_i^2}\) $$
- Width (W) inversely proportional to $\{\{Doping}}$
- Reverse Bias: $V_0 \ |V_0 + V|$ (W increases)
- Forward Bias: W decreases
Zero Bias
3.2 Diode Current Characteristic (I-V curve)
$$ I_f = I_0 \left[ e^{V_d / \eta V_T} - 1 \right] $$
- $\eta = 1$ for Ge, $\eta = 2$ for Si
- $I_0(T_2) = I_0(T_1) \times 2^{\frac{T_2 - T_1}{10}}$ (doubles every 10°C)
- 1°C rise → 7% increase in $I_0$
- $\frac{dv}{dt} = -2.5 \text{ mV/°C}$
3.3 Diode Resistance
$$ R_f = \frac{V}{I} \text{ (Static/DC)} $$
$$ r = \frac{\eta V_T}{I_f} \text{ (Dynamic/AC)} $$
$R_f$ is ALWAYS greater than $r$.
Forward resistance typically 10Ω - 100Ω.
3.4 Junction Capacitance
$$ C_T \propto \frac{1}{\sqrt[n]{V_{RB}}} \quad
\text{(Transition)} $$
$$ C_D = \frac{\tau I_f}{\eta V_T} \quad
\text{(Diffusion)} $$
- $C_T$ operates in Reverse Bias
- $C_D$ operates in Forward Bias
- $C_D \gg C_T$ always
Dielectric
Reverse
Bias: Plates separate
MODULE 4 — Special Purpose Diodes
4.1 Zener Diode (Voltage Regulator)
$$ I_Z = I_S - I_L $$
$$ V_Z = V_{Z0} + I_Z R_Z $$
- Heavily doped (1:10⁵), very thin depletion layer (< 10⁻⁶ m)
- Zener Breakdown: $< 6V$, strong E-field, Negative Temp Coefficient
- Avalanche Breakdown: $> 6V$, collisions, Positive Temp Coefficient
Operates in
Reverse Bias
Reverse Bias
4.2 Tunnel Diode
- Extremely heavily doped (1:10³)
- Used as high frequency oscillator
- Exhibits Negative Resistance
$$ I_p / I_v \approx 10 \text{ (Ge)} $$
4.3 Varactor Diode
$$ C_T = \frac{K}{(V_k + V_R)^n} $$
- Voltage-Variable Capacitor (VVC)
- Operates in Reverse Bias mode
- $n \approx 1/2$ (alloy), $n \approx 1/3$ (diffused)
C = 50.0 pF
4.4 Optoelectronic Diodes
LED (Light Emitting Diode)
$$ \lambda = \frac{hc}{E_g} =
\frac{1.24}{E_g \text{ (eV)}} \mu \text{m} $$
- Forward Bias operation
- Direct bandgap materials (GaAs, GaP)
Photodiode
$$ I_{photo} = \Re P_{in} = \left(\frac{\eta
q}{h\nu}\right) P_{in} $$
- Reverse Bias operation
- Current proportional to light intensity
Solar Cell
$$ FF = \frac{P_{max}}{V_{OC} I_{SC}} $$
- No external bias (Zero Bias)
- Generates V/I from photons
4.5 Schottky & PIN Diodes
Schottky Diode
- Metal-Semiconductor junction (Hot-carrier diode)
- Unipolar device (majority carriers only)
- High switching speed, very low forward voltage drop ($0.15 - 0.45V$)
- No reverse recovery time
PIN Diode
- Intrinsic layer between P and N regions
- Acts as variable resistor at RF/Microwave frequencies
- High frequency switching, phase shifters, attenuators
Schottky Symbol
PIN Structure
MODULE 5 — Regulated Power Supply
5.1 Power Supply Block Diagram
Hover over a block to see details
5.2 Rectifier Configurations
Input
vs Output Voltage Waveform
5.3 Ripple & Regulation
Ripple Factor (γ)
$$ \gamma = \frac{I_{RMS}'}{I_{DC}} =
\sqrt{\left(\frac{I_{RMS}}{I_{DC}}\right)^2 - 1} $$
- HWR: $\gamma = 1.21$ (121%)
- FWR: $\gamma = 0.48$ (48%)
Voltage Regulation
$$ \% V_R = \frac{V_{NL} - V_{FL}}{V_{FL}} \times 100 $$
Ideal regulation is 0%. Smaller value is
better.
5.4 Filters (Smoothing)
- Shunt Capacitor (C-Filter): Allows AC to bypass, blocks DC. Used for high load resistance (light load).
- Series Inductor (L-Filter): Blocks AC ripple, passes DC. Used for heavy loads.
- LC Filter (L-section): Better regulation. Ripple factor independent of load.
- π-Filter (C-L-C): Best smoothing, highest output DC voltage, but poor voltage regulation.
MODULE 6 — Bipolar Junction Transistor (BJT)
6.1 BJT Fundamentals
$$ I_E = I_B + I_C $$
$$ I_C = \alpha I_E + I_{CBO} $$
$$ I_C = \beta I_B + I_{CEO} $$
$$ \alpha = \frac{\beta}{1+\beta} \quad \beta =
\frac{\alpha}{1-\alpha} \quad \gamma = 1+\beta $$
Regions of Operation
| Region | EBJ | CBJ | Application |
|---|---|---|---|
| Active | Forward | Reverse | Amplifier |
| Saturation | Forward | Forward | Closed Switch |
| Cutoff | Reverse | Reverse | Open Switch |
| Inverse Act. | Reverse | Forward | Attenuator |
6.2 CB, CE, CC Configurations
| Feature | CB ($\alpha$) | CE ($\beta$) | CC ($\gamma$) |
|---|---|---|---|
| Input Z | Very Low (~20Ω) | Medium (~1kΩ) | High (~500kΩ) |
| Output Z | High (~1MΩ) | Medium (~40kΩ) | Low (~50Ω) |
| Voltage Gain | High | High | ~1 |
| Current Gain | < 1 | High | High |
| Phase Shift | 0° | 180° | 0° |