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Analog Electronics
Semiconductor Physics
Energy Band TheoryIntrinsic SemiconductorsExtrinsic Semiconductors N-TypeExtrinsic Semiconductors P-TypeCarrier ConcentrationDrift CurrentDiffusion CurrentEinstein RelationHall EffectContinuity Equation
Diodes & Applications
PN Junction FormationPN Junction Forward BiasPN Junction Reverse BiasDiode IV CharacteristicsShockley Diode EquationDiode Equivalent CircuitsDiode AC ResistanceZener DiodeZener Voltage RegulatorHalf Wave RectifierFull Wave Center Tap RectifierBridge RectifierCapacitor FilterPi FilterSeries ClipperShunt ClipperPositive ClamperNegative ClamperVoltage MultiplierLEDPhotodiodeVaractor DiodeTunnel DiodeSchottky Diode
BJT Amplifiers
BJT Structure and ConstructionBJT NPN OperationBJT PNP OperationBJT Current RelationshipsBJT Operating RegionsBJT Input Output CharacteristicsFixed Bias CircuitCollector Feedback BiasVoltage Divider BiasEmitter BiasBJT Bias StabilityCommon Emitter AmplifierCommon Base AmplifierCommon Collector AmplifierBJT Small Signal ModelH Parameter AnalysisBJT Frequency ResponseMultistage AmplifiersDarlington PairCascode AmplifierDifferential AmplifierPower Amplifiers Class APower Amplifiers Class BPower Amplifiers Class AB
FET Amplifiers
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Operational Amplifiers
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Oscillators & Timers
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Filters
Passive RC Low Pass FilterPassive RC High Pass FilterActive Low Pass FilterActive High Pass FilterActive Band Pass FilterActive Band Stop FilterButterworth Filter DesignChebyshev Filter DesignBessel FilterFilter Frequency Response
Power Electronics Basics
Linear Voltage Regulator78xx 79xx SeriesAdjustable Voltage Regulator LM317Switching Regulator Basics
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Other Subjects
Digital ElectronicsSignals & SystemsControl SystemsElectromagnetic TheoryDigital CommunicationAnalog CommunicationNetwork AnalysisMicroprocessorsVLSI DesignVerilog HDLPower ElectronicsEmbedded SystemsDSPElectronic Devices
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15 of 24 articles

BJT Small Signal Model

Hybrid pi model, transconductance gm, input resistance rpi.

Mohith N
Updated: 27 March 2026
8 min read
#BJT

Small Signal Models

Calculate hybrid-pi model parameters for BJTs.

Question 1 of 3

Q1.How is the transconductance (gm) of a BJT calculated at room temperature?

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Small Signal Model

Diode resistance and conductance.

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BJT Input Output Characteristics

IC vs VCE, IB vs VBE curves, Early effect.

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BJT NPN Operation

Forward active NPN, electron injection, base recombination.

11 min read

BJT PNP Operation

Forward active PNP, hole injection, complementary to NPN.

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BJT Structure and Construction

NPN and PNP layers, emitter-base-collector doping profiles.

5 min read

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