Analog Formula Reference, Glossary & Self-Assessment
A compact reference for the whole course. The key formulas grouped by topic (circuits, devices, amplifiers, op-amps, filters, feedback/stability, oscillators, power, noise and converters), a glossary of essential analog terms, a self-assessment path by level, and a Python 'formula self-check' that evaluates the core formulas with standard values so you can test your own hand calculations.
After working through the course, you need a quick place to look up a formula, recall a definition or test yourself. This lesson collects the essentials and points back to the detailed lessons.
Use the self-check: compute each value by hand first, then compare with the verified Python output below.
An analogy
This lesson is the toolbox lid: every tool (formula) is outlined in its place so you can grab the right one quickly — the lessons are where you learned how to use each tool.
Glossary A–F
Essential terms:
- Bandwidth — frequency range where gain is within 3 dB of midband
- Bias / Q-point — DC operating point of a device
- CMRR — ability to reject signals common to both inputs
- Compliance — voltage range over which a current source works
- Decibel — 20 log (voltage ratio) or 10 log (power ratio)
- Dropout — minimum V_in − V_out for regulation
- ENOB — effective number of bits from SINAD
- ESR/ESL — parasitic series resistance/inductance of capacitors
- Feedback factor β — fraction of output returned to input
Glossary G–R
More terms:
- GBW — gain × bandwidth, constant for dominant-pole amplifiers
- Headroom — margin between nominal level and clipping
- Hysteresis — different thresholds for rising and falling inputs
- INL/DNL — converter linearity errors
- Loop gain T = Aβ — determines feedback benefits and stability
- Miller effect — feedback capacitance multiplied by (1 + |A|)
- Noise figure — added noise relative to source noise
- Phase margin — distance from −180° at loop crossover
- PSRR — rejection of supply variations
- Ratiometric — measurement referenced to the excitation source
Glossary S–Z
And the rest:
- SFDR — distance from carrier to largest spur
- Slew rate — maximum output dV/dt
- SOA — safe operating area of power devices
- Settling time — time to reach and stay within an error band
- THD — total harmonic distortion
- Transconductance g_m — output current per input voltage
- Virtual ground — node held at ground potential by feedback
- Zero-drift — chopper/auto-zero amplifiers with µV offset
Self-assessment path
Beginner check: compute dB conversions, divider outputs, RC corners, diode operating points. Intermediate: bias and analyse a CE stage, design op-amp gain stages and a Sallen-Key filter, size a 555 timer. Advanced: estimate bandwidth with Miller, phase margin with capacitive loads, noise budgets, ADC front-end settling. Professional: produce an error budget, a level diagram, a compensated two-stage op-amp and a verified capstone report. Each lesson's problem and quiz form the assessment bank.
Formulas
- Circuits:
V = IR; f_c = 1/(2πRC); f₀ = 1/(2π√(LC)); τ = RC, L/R - Devices:
I_D = I_S(e^(V/nV_T) − 1); g_m = I_C/V_T (BJT), 2I_D/V_OV (MOS); r_o = V_A/I - Amplifiers:
A_v = −g_m R_C; degenerated −R_C/(r_e + R_E); Miller C(1 + |A|) - Op-amps:
−R_f/R_in; 1 + R_f/R_g; BW = GBW/NG; f_FP = SR/(2πV_p) - Feedback & stability:
A_f = A/(1 + Aβ); PM = 180° + ∠T(f_c) - Power & converters:
η_lin = V_o/V_i; buck D = V_o/V_i; SNR = 6.02N + 1.76; noise √(4kTR·B)
Worked example: dB to ratio
Given: −6 dB (voltage)
Find: Ratio.
- 10^(−6/20)
Answer: 0.501
Worked example: Op-amp bandwidth
Given: GBW 10 MHz, gain 20
Find: Bandwidth.
- 10 MHz/20
Answer: 500 kHz
Worked example: Thermal voltage
Given: T = 350 K
Find: V_T.
- kT/q = 1.381e−23 × 350/1.602e−19
Answer: ≈ 30.2 mV
Where to find each topic
Foundations ........ signals/dB, circuit analysis, passives, transients
Devices ............ semiconductor physics, diodes, special diodes, opto, rectifiers, wave-shaping
Transistors ........ BJT, biasing, BJT amps, FETs, FET amps, small-signal/Miller, frequency response
Op-amps ............ diff pairs, mirrors, op-amp basics/circuits/applications, comparators
Signal processing .. filters, feedback, stability, oscillators, 555/waveforms
Power .............. power amps, thermal, linear/switching regulators, references
Precision .......... noise, distortion, signal conditioning, error budgets
Mixed-signal & ICs . ADC front end, DAC, switches/SC, OTA design, PLL/comms
Practice ........... measurement, debugging, PCB/EMI, SPICE, components, control
Projects ........... applications, patterns/labs, capstonesThe course is organised as a path from foundations to professional practice; each line lists the lessons that go deeper into the formulas summarised here.
Formula self-check
import math
# Formula self-check: evaluate a handful of core analog formulas with standard example values
checks = {
"RC corner 1k/100n (Hz)": 1 / (2 * math.pi * 1e3 * 100e-9),
"gm at 1 mA (mA/V)": 1e-3 / 0.02585 * 1e3,
"non-inverting gain Rf 9k Rg 1k": 1 + 9e3 / 1e3,
"LC resonance 10uH/100nF (kHz)": 1 / (2 * math.pi * math.sqrt(10e-6 * 100e-9)) / 1e3,
"thermal noise 1k (nV/rtHz)": math.sqrt(4 * 1.380649e-23 * 300 * 1e3) * 1e9,
"12-bit ideal SNR (dB)": 6.02 * 12 + 1.76,
"buck duty 12->5 V": 5 / 12,
"555 astable 10k/10k/10n (Hz)": 1.44 / ((10e3 + 20e3) * 10e-9),
"full-power BW 0.5 V/us, 5 V pk (kHz)": 0.5e6 / (2 * math.pi * 5) / 1e3,
"-3 dB as voltage ratio": 10 ** (-3 / 20),
}
for k, v in checks.items():
print(f"{k:38s} {v:10.4g}")
# RC corner 1k/100n (Hz) 1592
# gm at 1 mA (mA/V) 38.68
# non-inverting gain Rf 9k Rg 1k 10
# LC resonance 10uH/100nF (kHz) 159.2
# thermal noise 1k (nV/rtHz) 4.07
# 12-bit ideal SNR (dB) 74
# buck duty 12->5 V 0.4167
# 555 astable 10k/10k/10n (Hz) 4800
# full-power BW 0.5 V/us, 5 V pk (kHz) 15.92
# -3 dB as voltage ratio 0.7079Work each value out by hand first: 1.59 kHz, 38.7 mA/V, gain 10, 159 kHz, 4.07 nV/√Hz, 74 dB, D = 0.417, 4.8 kHz, 15.9 kHz and 0.708. If your answer differs, revisit the corresponding lesson.
Common mistakes
- Wrong: Using 10 log for voltage ratios. — Right: 20 log for voltage/current, 10 log for power.
- Wrong: Forgetting 2π in corner frequencies. — Right: f = 1/(2πRC); ω = 1/(RC).
- Wrong: Treating V_T as constant. — Right: It is proportional to absolute temperature.
Applications
- Exam revision: One-page formula summary.
- Design reviews: Quick sanity checks.
- Interviews: Common analog interview questions.
- Lab work: Predictions before measurement.
Key takeaways
- Keep a compact formula sheet and rules of thumb.
- Voltage dB = 20 log; power dB = 10 log.
- Self-check by hand before trusting tools.
- Each lesson's problems form the assessment bank.
Going further
- Dimensional analysis: Checking formulas by units.
- Estimation skills: Back-of-envelope before simulation.
- Interview problem sets: Classic analog puzzles.