Ontological Layer: Signal Control Systems

Amplifiers

Power Supply Control via Signal Modulation

The Illusion of Creation

An amplifier does not create signal energy from nothing. It is a control valve. The small input signal directs the active device (BJT or FET) to modulate a larger energy flow drawn continuously from the DC power supply. This realm explores the configurations, cascades, limitations, and models used to engineer this controlled power transfer.

INPUT SIGNAL → DC BIAS → DEVICE MODEL → POWER SUPPLY → MODULATION → GAIN (A) → LOADING / DISTORTION → OUTPUT SIGNAL

The 12 Amplifier Sub-Realms

Ontological Mapping: Nodes 01 - 127

GROUP 01-10

Concept & Classification

01 The Amplifier Concept
08 Role of the Power Supply
09 Energy Transfer Mechanism
10 Voltage vs Current vs Transconductance

GROUP 11-20

BJT Topologies

12 Common-Emitter (CE) High Av, Ai
13 Common-Base (CB) High Av, Ai≈1
14 Common-Collector (CC) Buffer
15-18 Gain & Resistance Parameters

GROUP 21-28

FET Topologies

22 Common-Source (CS) High Rin
23 Common-Gate (CG) Low Rin
24 Common-Drain (CD) Source Follower
28 Transconductance (gm) Focus

GROUP 29-38

Gain & Equivalent Models

29 Amplifier Equivalent Circuits
30 Small-Signal Modeling
35 Voltage (Av), 36 Current (Ai) Gain
38 Gain expressed in Decibels (dB)

GROUP 31-34, 45

Source & Load Interactions

31 Source Resistance (Rs) loading
32 Load Resistance (RL) loading
33 Input (Rin) & 34 Output (Rout) Impedance
45 Loading Between Cascaded Stages

GROUP 39-48

Multistage Amplifiers

39 Gain Cascading (Multiplication)
42-44 Overall Av, Ai, Ap calculation
46 Interstage Coupling Methods
RC vs Transformer vs Direct Coupling

GROUP 49-61

Frequency Response

50 Low-Freq (Coupling/Bypass caps)
51 Midband (Constant Gain)
52 High-Freq (Internal Device caps)
55 Bandwidth (BW) & Cutoff Frequencies

GROUP 62-66

The Miller Effect

62 Transistor Internal Capacitances
64 The Miller Effect Principle
65 Multiplication of Feedback Capacitance
Impact on High-Frequency Response

GROUP 76-86

Power Amplifier Classes

76 Efficiency vs Linearity Trade-off
78 Class A (360° conduction, low eff)
79 Class B (180°, Push-Pull, high eff)
80 Class AB (Crossover dist. mitigation)

GROUP 87-94

Differential Amplifiers

88 Differential Input (+ / -)
89 Differential vs 90 Common-Mode Gain
91 Common-Mode Rejection Ratio (CMRR)
92 Active Loads & Current Mirrors

GROUP 67-75, 102-104

Non-Idealities & Limits

CLIPPING

68 Types of Distortion (Harmonic, IMD)
69 Noise (Thermal, Shot, Flicker)
74 Signal Clipping & 75 Saturation
104 Slew Rate & Large-Signal Limits

FINAL PROTOCOL

12 — Amplifier Design Laboratory

Av = -gm * (Rc || RL)

Av(dB) = 20 log|Av|

fH = 1 / (2π * Rth * Cin_miller)

[109] DESIGN SPECS [124] NUMERICAL PROBLEMS [125] BODE PLOT CALCS [117] TESTING [119] TROUBLESHOOTING

Executing the algorithmic process of amplifier design. Moving from target specifications (Gain, BW, Power) to actual component selection, analyzing frequency roll-offs, and diagnosing clipped or distorted signals in the physical circuit.

SIMULATION RUNNING