Units: Volts (V)

Expected Range: Typically between -6V and 0V for N-channel JFETs and 0V to 6V for P-channel JFETs.

Example Value: -2.0V for an N-channel JFET.

Impact: VTO determines the gate-source voltage (Vgs) at which the JFET begins to conduct. Modifying VTO in simulations allows users to explore how different threshold voltages affect the device's operation, particularly the transition between cutoff and saturation regions.

Units: Amperes per Volt Squared (A/V^2)

Expected Range: Varies widely depending on the JFET but is generally in the range of 1.0e-4 to 1.0e-2 A/V^2.

Example Value: 1.0e-3 A/V^2 for a typical JFET.

Impact: BETA affects the slope of the ID-VGS curve in the ohmic region, essentially determining how effectively the JFET can amplify a signal. Adjusting BETA helps simulate JFETs with different amplification capabilities.

Units: Per Volt (/V)

Expected Range: 0 to 0.02 /V.

Example Value: 1.0e-4 /V.

Impact: LAMBDA models the variation of drain current (ID) with drain-source voltage (VDS) due to the channel-length modulation effect. It influences the output characteristics, particularly in the saturation region, simulating how ID changes as VDS increases.

Units: Ohms (Ω)

Expected Range: 0 to a few hundred Ohms.

Example Value: 100Ω.

Impact: RD represents the resistance in the path between the drain and the channel. It impacts the voltage drop across the drain terminal and the total output resistance of the JFET, affecting the output characteristics.

Units: Ohms (Ω)

Expected Range: 0 to a few hundred Ohms.

Example Value: 100Ω.

Impact: Similar to RD, RS affects the voltage drop across the source terminal and influences the overall gain and output impedance of the JFET.

Units: Farads (F)

Expected Range: Picofarads (pF) to nanofarads (nF).

Example Value: 5pF.

Impact: CGS affects the frequency response of the JFET, particularly its input capacitance and thus its bandwidth. Higher values can lead to slower response times.

Units: Farads (F)

Expected Range: Picofarads (pF) to nanofarads (nF).

Example Value: 1pF.

Impact: CGD influences the Miller effect, which can significantly affect the voltage gain and bandwidth of amplifiers using JFETs.

Units: Volts (V)

Expected Range: 0.5V to 1V for typical JFETs.

Example Value: 0.6V.

Impact: PB affects the gate-source and gate-drain diode characteristics, particularly their reverse-bias behavior, which is important for understanding leakage currents and breakdown voltages.

Units: Amperes (A)

Expected Range: Very small, typically in the range of 1.0e-14 to 1.0e-16 A.

Example Value: 1.0e-14 A.

Impact: IS impacts the off-state leakage current through the gate, which is critical for low-power applications and determining the off-state device behavior.

Units: Dimensionless

Expected Range: 1 and above.

Example Value: 1.1.

Impact: This parameter models the doping profile of the JFET's channel. A higher value suggests a more abrupt transition from the channel to the doped regions, which can affect the device's turn-on characteristics and channel resistance. It is useful for simulating devices with non-uniform doping profiles.

Units: Dimensionless

Expected Range: Typically very small or zero.

Example Value: 0 (for simplicity in basic simulations).

Impact: KF represents the coefficient for 1/f noise or flicker noise in the JFET. This type of noise is significant in low-frequency applications. By adjusting KF, users can explore how flicker noise impacts the low-frequency performance of amplifiers or oscillators.

Units: Dimensionless

Expected Range: Usually close to 1.

Example Value: 1 (common default).

Impact: AF modifies the frequency dependency of the flicker noise, affecting how noise power density changes with frequency. This parameter is crucial for noise analysis in audio and other low-frequency applications.

Units: Dimensionless

Expected Range: 1, 2, 3, etc., depending on the model.

Example Value: 3 (for advanced noise modeling).

Impact: NLEV selects the noise model used in simulations, allowing users to choose between different methods of noise analysis. This flexibility is valuable for accurate noise performance predictions in sensitive applications.

Units: Dimensionless

Expected Range: 1 and above.

Example Value: 2.0.

Impact: GDSNOI is relevant when using advanced noise models (e.g., NLEV=3), affecting the simulated channel noise. It allows for detailed noise modeling, particularly in high-frequency or precision applications.

Units: Dimensionless

Expected Range: 0 to 1.

Example Value: 0.5 (typical).

Impact: FC modifies the voltage dependency of the junction capacitances (CGS and CGD), particularly under forward bias conditions. This affects the charging behavior of the gate junctions, influencing AC performance and transient response.

Units: Degrees Celsius (°C)

Expected Range: Typical lab conditions, e.g., 25°C.

Example Value: 27°C.

Impact: TNOM specifies the temperature at which the JFET parameters were measured. This is the reference point for temperature-dependent simulations, crucial for accurately modeling device behavior over a range of operating temperatures.

Units: Per Degree Celsius (/°C)

Expected Range: Small, typically around 0.01 to -0.01 /°C.

Example Value: 0.01 /°C.

Impact: TCV models how the threshold voltage changes with temperature. This is important for designing circuits that operate reliably over a wide temperature range, as it affects the turn-on characteristics of the JFET.

Units: Per Degree Celsius (/°C)

Expected Range: Similar to TCV but used in alternative models.

Example Value: -2.5m /°C.

Impact: Like TCV, VTOTC allows for temperature-dependent threshold voltage modeling in alternative JFET models. It offers additional flexibility in simulating temperature effects.

Units: Dimensionless

Expected Range: 0 to 2.

Example Value: 1.1.

Impact: BEX models the temperature dependency of the carrier mobility. This affects the JFET's transconductance and saturation current over temperature, critical for thermal performance analysis.

Units: Percent per Degree Celsius (%/°C)

Expected Range: Typically negative values.

Example Value: -0.5.

Impact: BETATCE is another parameter for modeling the temperature dependency of carrier mobility, used in alternative models. It helps simulate how the device's gain changes with temperature.

Units: Dimensionless

Expected Range: 2 to 4, typical for semiconductor junctions.

Example Value: 3.0.

Impact: XTI affects how the gate saturation current varies with temperature, which is vital for predicting leakage currents and power dissipation in different thermal conditions.

Units: Volts (V)

Expected Range: Around 1.11V for silicon devices.

Example Value: 1.11V.

Impact: EG specifies the semiconductor material's bandgap energy, impacting various temperature-dependent behaviors, including saturation current and threshold voltage shifts.

Unit: Dimensionless

Range: {1, -1}

Example: 1 for vertical geometry, -1 for lateral geometry.

Impact: Determines the geometry of the transistor, affecting its electrical properties and how it interacts with the substrate.

Unit: Ampere (A)

Range: Typically in the range of 1.0e−161.0e−16 to 1.0e−121.0e−12 A.

Example: 1.0e-16 A for small signal transistors, 1.0e-15 A for power transistors.

Impact: Influences the transistor's active region characteristics. A key parameter for determining the DC current gain.

Unit: Ampere (A)

Range: Usually very small, similar to IS.

Example: 1.0e-16 A.

Impact: These parameters affect the leakage currents in the transistor, impacting the off-state behavior and reverse-bias characteristics.

Unit: Ampere (A)

Example: 1.0e-15 A.

Impact: Determines the substrate leakage current, significant for vertical devices.

Unit: Dimensionless

Range: Typically 50 - 300 for small signal transistors, higher for power transistors.

Example: 100.

Impact: Directly influences the transistor's current gain in the forward-active mode.

Unit: Dimensionless

Range: Close to 1, usually between 1 and 2.

Example: 1.0.

Impact: Affects the linearity and efficiency of the transistor, influencing the forward current gain.

Unit: Volt (V)

Range: Can be very high (tens to hundreds of volts) or infinity.

Example: 200 V.

Impact: Indicates the voltage dependence of the transistor's base width, impacting high-voltage behavior and gain.

Unit: Ampere (A)

Range: Depends on the transistor type; higher for power transistors.

Example: 0.01 A.

Impact: Determines the point at which the current gain starts to decrease with increasing collector current.

Unit: Dimensionless

Range: Typically around 1.5 to 2.

Example: 1.5 for NE, 2 for NC.

Impact: Affects the base-emitter and base-collector junctions' I-V characteristics, important for modeling non-ideal behaviors.

Unit: Ohm (Ω)

Range: Varies widely based on transistor design and application.

Example: 100 Ω for RB, 1 Ω for RE, 10 Ω for RC.

Impact: Represents the internal resistances of the transistor, affecting the voltage drops and power dissipation.

Unit: Farad (F), typically in pF.

Range: Varies with transistor size and design; smaller for high-frequency transistors.

Example: 2pF for both CJE and CJC.

Impact: Critical for high-frequency operation, affecting the speed of the transistor by introducing charging and discharging times.

Unit: Volt (V)

Range: Typically around 0.6 to 0.7 V for silicon transistors.

Example: 0.6 V for VJE, 0.5 V for VJC.

Impact: Determines the turn-on characteristics of the junctions, essential for accurate threshold voltage modeling.

Unit: Dimensionless

Range: Typically around 0.33 to 0.5.

Example: 0.33 for MJE, 0.5 for MJC.

Impact: Affects the voltage dependence of the junction capacitances, impacting the transistor's frequency response.

Unit: Second (sec), typically in ns or ps.

Range: Varies with the speed of the transistor; shorter for faster devices.

Example: 0.1ns for TF.

Impact: Directly affects the switching speed of the transistor, crucial for digital and high-frequency applications.

Unit: °C for temperature, dimensionless or /°C for coefficients.

Example: 27 °C for TNOM.

Impact: These parameters adjust the model to simulate the temperature dependence of the transistor's behavior, critical for thermal stability and performance analysis.