Analog Circuits From Scratch

Explore pn junctions and biasing fundamentals for analog circuits, including depletion regions, forward and reverse bias, and the basic operation of diodes and transistors in silicon and germanium semiconductors.

Learn diode symbols and circuits, with forward bias enabling current and reverse bias blocking it. Compare practical diodes to the ideal model and note 0.7 V drop and current-limiting resistor.

Examine the v–i characteristics of a diode, including forward bias, threshold (barrier potential), and non-linear behavior, and apply the ideal diode model with forward short and reverse open circuits.

Determine which diode conducts by making an assumption, then use a roughly 0.7 V forward drop to compute node voltages and currents in the circuit.

Solve diode circuits in analog circuits from scratch for problem 2, applying three rules to guide the solution.

Learn how a dc power supply converts mains ac to dc using transformer, rectifier, filter, and regulator to deliver a stable voltage for electronic devices.

Explore how a half-wave rectifier uses a diode to convert ac into pulsating dc, analyze the rectified output, and define key performance measures like average dc, ripple factor, and form factor.

Explore a basic half wave rectifier problem to compute the peak input and derive the average output, rms value, ripple factor, and form factor for performance assessment.

Explore how a center-tapped transformer enables full-wave rectification by coordinating two diodes during the positive and negative half cycles, analyzing forward and reverse bias, ripple, and the output waveform.

Analyze how filters reduce ripple in rectifier circuits by shaping the frequency response with low-pass, band-pass, and band-reject filters and cutoff concepts.

Explore how HWR and FWR with capacitor filters use charging and discharging to smooth rectified signals, block DC, and reduce ripple through frequency and load resistance.

Analyze how a rectifier with a filter affects ripple and ripple factor under specific input signal and frequency conditions, and interpret results like 5.7 to understand the ripple outcome.

Explore how regulators maintain a constant output voltage despite input fluctuations, using a reference voltage, a comparator, and feedback, and classify them as linear, switching, fixed, or shunt.

Illustrate the series voltage regulator block diagram, where a transistor acts as the control element in series with the load and rectifier input, with feedback maintaining a constant output.

Explore the shunt voltage regulator block diagram, showing how a control element, feedback, comparator and reference regulate the output to stay constant.

Examine the waveforms across key stages of an ac to dc power supply, including transformer, rectifier, and regulator, and how the regulator maintains a constant output despite ripple.

Explore transistor basics within analog design, comparing it to diodes and focusing on three-terminal operation, with classifications into bipolar junction transistors and field effect transistors, including MOS and depletion/enhancement modes.

Explore the BJT fundamentals, including emitter, base, and collector sections, biasing, and the three modes: active, saturation, and cutoff, along with the NPN symbol and amplification in active mode.

Bias a transistor to keep it in the active region for faithful amplification, using dc bias and the load line to set the q point, base voltage, and collector current.

Explore transistor configurations - common emitter, common base, and common collector - highlighting how input, output, and current gains relate, with beta and alpha relationships and typical ranges.

Explore the common emitter amplifier by biasing the transistor with a voltage divider, examining coupling and bypass capacitors, and the role of negative feedback in stabilizing gain.

Explore how an amplifier's frequency response shows gain variation with frequency, where low frequencies are attenuated by input coupling and high frequencies by output coupling, within the bandwidth in decibels.

Explore how a BJT current mirror replicates a reference current with two identical transistors and a diode-connected transistor, and how variations affect matching.

Derive the current transfer ratio for a current mirror by analyzing collector and base currents and beta, showing the current transfer ratio can equal one and depends on transistor area.

Analyze current mirrors in a transistor circuit to guide you through computing the output current and the transfer ratio from given values.

Explore the Darlington pair as a compound, multi-stage amplifier built from two transistors to achieve high current gain, and see why a single transistor cannot reach gains like 5500.

The lecture compares bjt and fet amplifiers, noting bjt as current-controlled with higher heat and noise, while fet offers voltage control, better heat stability, higher input impedance, and higher gain.

Explore field effect transistors, including junction field effect transistors and MOSFETs, their depletion type and enhancement type, and how the channel formed by electrons or holes shapes their operation.

Explore the construction and operation of an n-channel depletion-type MOSFET, including the gate oxide, depleted channel, and biasing that controls drain–source current.

Apply a positive gate voltage to attract electrons into the mosfet channel, increasing the drain current, while a negative gate voltage depletes the channel and reduces conduction.

Explore the output characteristics of a n-channel depletion-type MOSFET, showing how drain current responds to gate voltage, with saturation behavior and the depletion-mode opposite trend.

Illustrate the transfer characteristics curve of a n-channel depletion-type MOSFET, showing the relation between input and output and how output varies with negative and positive input values.

Learn how an NMOS transistor is built and works, including channel formation by inversion, threshold voltage, and the difference between enhancement and depletion modes in a MOSFET.

Explore the transfer characteristics of an NMOS, showing how gate input above a threshold forms a channel and enables output current, with regions of operation and threshold behavior.

Explore how a MOSFET operates as an amplifier in saturation, derive its voltage gain from small-signal models, and relate it to gm and device parameters.

Explore MOSFET current mirrors: how current transfer depends on device width and channel length ratios, yielding ratio-based accuracy and high fidelity compared to absolute sizing, with a reference transistor.

Explore the differential amplifier: it amplifies the difference between two inputs while rejecting common-mode voltages, and learn about common-mode rejection ratio (CMRR) and its practical implications.

Explore the essential pre-requisite concepts for differential amplifiers by examining transistor operation, including base input, saturation and cutoff, short and open circuits, and how current and voltage relate.

Analyze the voltage and current curves of a differential amplifier, showing how input voltages V1 and V2 yield open and closed circuit states and maximum current when inputs differ.

power amplifiers deliver high current gain with modest voltage gain to drive loudspeakers, supplying sufficient power for audio. classification covers class c, class b, and related efficiency and operating considerations.

Explore class a power amplifiers using a high power transistor with fixed base bias, examining biasing, collector current, input signals, and a 25 percent efficiency.

Explore class B amplifiers through a complementary push-pull configuration using an NBN transistor and another transistor, with input coupling capacitors and a junction output that switches conduction.

Explain how a class b amplifier produces crossover distortion, showing dead bands and output deviating from input, and note that avoidance will be discussed in later content.

explain class ab amplifiers as a biasing solution to reduce crossover distortion, keeping transistors active like class b, and discuss the 78.5 percent class b efficiency.

Explain tuned amplifiers that select a specific frequency, bias transistors below cutoff, and conduct for less than 180 degrees to achieve high efficiency around 90 percent in class c.

design a common-source amplifier with a resistive load to achieve a gain of 20; derive gm from the saturation current equation and set rd to 10 kΩ.