PIN_diode (PIN Diode)


Available in ADS and RFDE

Name Description Units Default
Area Area scaling factor None 1.0
Temp Device operating temperature °C 25.0
Trise Temperature rise above the circuit ambient (if Temp not specified) °C 0.0
Tnom Temperature at which device parameters were established °C 25.0
Noise Noise generation option: yes, no None yes
Model_level Model level selector: 1=SPICE Cj model, 2=advanced Cj model None 1
Is †, †† Saturation Current A 1.0e-14
N Emission coefficient None 1.0
B PI-IN emission coefficient splitting factor None 1.0
Ikf †† High-injection knee current (0.0 means infinity) A infinity
Bv Reverse breakdown voltage (0.0 means infinity) V infinity
Ibv Current at reverse breakdown voltage A 0.001
Rs †, ††† Diode ohmic resistance Ohms 0.0
Rp †, ††† Junction parallel resistance Ohms 1.0e9
Repi †, ††† Zero-bias resistance Ohms 1.0e3
Rlim †, ††† Minimum series resistance Ohms 1.0e-3
W I-region width m 1.0e-4
Wd Depletion area width m 1.0e-6
Tau Ambipolar carrier lifetime sec 1.0e-6
Iknee Current dependent lifetime knee current (0.0 means infinity) A infinity
Rho I-region resistivity Ohm × m 0.0
Eps I-region dielectric constant None 11.9
Cj †, †† Zero-bias capacitance F 1.0e-15
Vj Junction potential V 1.0
M Grading coefficient None 0.0
Fc Forward-bias depletion capacitance coefficient None 0.5
Eg Energy gap eV 1.11
Xti Temperature exponent for Is None 3.0
Trs Linear relative temperature coefficient for Rs 1/°C 0.0
Trs2 Quadratic relative temperature coefficient for Rs 1/(°C) 2 0.0
Trp Linear relative temperature coefficient for Rp 1/°C 0.0
Trp2 Quadratic relative temperature coefficient for Rp 1/(°C) 2 0.0
Trepi Linear relative temperature coefficient for Repi 1/°C 0.0
Trepi2 Quadratic relative temperature coefficient for Repi 1/(°C) 2 0.0
Trlim Linear relative temperature coefficient for Rlim 1/°C 0.0
Trlim2 Quadratic relative temperature coefficient for Rlim 1/(°C) 2 0.0
Tm1 Linear relative temperature coefficient for M 1/°C 0.0
Tm2 Quadratic relative temperature coefficient for M 1/(°C) 2 0.0
Tbv Temperature coefficient for Bv V/°C 0.0
Kf Flicker noise coefficient 0.0
Af Flicker noise exponent None 1.0
Ffe Flicker noise frequency exponent None 1.0
Cpack †† Package parasitic capacitance F 0.0
Lbond ††† Package parasitic inductance H 0.0
Imax Explosion current A 1.0
_M Number of devices in parallel None 1
Parameter value varies with the temperature based on Tnom and Temp †† Parameter value scales with Area ††† Parameter value scales inversely with Area

Range of Usage

All parameters, except Trise and temperature coefficients Txxx, should be either positive or non-negative. Model_level can currently be 1 or 2. Out-of-range parameter values for Area, Temp, Tnom and W are reset to their default values. Parameters which are subject to temperature scaling are clipped at a small positive number or zero if, after scaling, their values become too small.

  1. The PIN diode device does not use a model card. All parameters are specified on each instance of the PIN diode device.
  2. For Model_level = 1 the standard SPICE diode equation is used to model the junction capacitance. Specifically, a linear extension is used for V D > Fc × Vj.
  3. For Model_level = 2 the advanced model equations of [1] are implemented. However, for Transient simulations the frequency dependence of the junction capacitance could significantly affect the robustness of the simulation, and thus is disabled. This may create some discrepancies between Harmonic Balance and Transient simulation results.
  4. The device operating temperature T is either equal to the value of the parameter Temp, if it is specified, or defaults to the global (ambient) circuit temperature specified by the parameter Temp in the Options controller and modified by the value of Trise:
    _ T = circuit_ambient_temperature_ + Trise
    If Temp is not specified in the Options controller, the circuit ambient temperature defaults to 25°C.
  5. Tnom parameter, if not specified, defaults to the global value of Tnom as specified in the Options controller. If it is not specified in the Options controller, default is 25°C.
  6. Imax Parameter
    Imax specifies the P-N junction explosion current. The global value of Imax given in the Options controller is not used as the default value if the PIN diode parameter Imax is not specified. The default value remains as shown in the table.
  7. The parameter Rs is the series ohmic resistance of the diodes DPI and DIN shown in Equivalent Circuit. The overall PIN diode series resistance is not Rs, but rather a combination of Repi, Rlim and GRMOD, and is also affected by other parameters.
  8. Implementation of the PIN_diode model is based on [1-4]

Equations - Diode Current

The PIN diode main current equation follows that of the standard PN diode but comes as a result of two diodes connected in series: DPI and DIN, in addition to being processed by the controlled sources as shown in Equivalent Circuit. The two diodes share the following parameters:

Area, Temp, Tnom, Is, Rs, Ikf, Bv, Ibv, Trs, Trs2 and Tbv.

but may have different emission coefficients as

if the model parameter B is different from 1.0.

The diode current is affected by the RC sub-circuit which is devised to model the impact of the charge storage in the I-region and its lifetime. The component values of the RC sub-circuit are defined as follows:
, ,

where i = 1, 2, ... , 5,

and Tau and W are model parameters.

The main diode current IS2 is fed back to the main diode branch through a CCCS with a gain of 1.
To establish the current in the main diode branch, its voltage Vpin is sensed by a VCVS and applied (with a gain of 1) directly to the diodes DPI and DIN. The current IS1 through the two diodes excites the RC sub-circuit via a CCVS with a trans-resistance of 1.

Finally, in addition to a limiting resistance Rlim and the zero-bias resistance Repi the diode current is affected by two nonlinear resistors, marked in the equivalent circuit as GRMOD and GE.
The current i~GE~ in GE is expressed in terms of its voltage v~GE~ as:

where Iknee is a model parameter and Σ = 10 -12.

The GRMOD component is actually a voltage controlled resistance and its current i GRMOD is expressed in terms of its voltage v GRMOD and of the controlling voltage v rp1 as:


and Tau and W are model parameters.

Equations - Diode Capacitance

The default setting of the parameter M (M = 0) makes the junction capacitance to be linear with its value specified by the parameter Cj.

For M > 0 and VD < Fc × Vj the standard SPICE nonlinear capacitance equation is used

where VD is the voltage across the capacitance and Cj, Fc and Vj are model parameters.

The extension of this equation beyond Fc × Vj is controlled by the parameter Model_level.

For Model_level = 1 (default) and V D > Fc × Vj the standard linear extension is used


For Model_level = 2 and Fc × Vj < V D < (2-Fc) × Vj the quadratic extension is used:

which is followed by a decaying exponential extension for V D > (2-Fc) × Vj, defined as follows.

Additionally, for Model_level = 2, a frequency dependence of Cj is incorporated into the capacitance equation using the following factor, if the model parameter Rho is specified and greater than zero. By default Rho = 0 and the frequency dependence of Cj does not take effect, i.e., the factor is set to 1.0.

where f r is the dielectric relaxation frequency

, ,

Rho, Eps, Wd and W are model parameters, and Σ0 is the permittivity of vacuum.

Other RLC Components

The parameters Rp, Repi, Rlim, Cpack and Lbond provide the component values for the respective components. Rp is the junction parallel (leakage) resistance. Repi is the zero-bias series diode resistance. Rlim establishes the minimum diode resistance. Cpack and Lbond are the package parasitic capacitance and inductance, respectively.

Temperature Scaling Relations

Temperature scaling is performed when the operating device temperature T (see Note_4)_is_different_from_Tnom._The_temperature_scaling_relations_used_for_the_PIN_diode_are_the_same_as_for_the_PN_diode_with_Tlev_=_0_and_Tlevc_=_0._This_includes_scaling_of_the_saturation_current_Is,_the_breakdown_voltage_Bv,_the_grading_coefficient_M,_the_junction_potential_Vj,_the_junction_capacitance_Cj,_as_well_as_the_thermal_voltage_in_the_equation_for_the_diode_current._See_Diode_Model (PN-Junction Diode Model) for more information.

Additionally, the resistances Rs, Rp, Repi and Rlim are scaled in the same way as the resistor component.

Dimensional Scaling Relations

If the parameter Area is different from 1.0 then the dimensional scaling is performed on several model parameters, as indicated in the parameter table for Area.

Noise Model

Thermal noise generated by resistors Rs, Rp, Repi and Rlim is characterized by the following spectral density:

where R=Rs, Rp, Rlim or Repi, respectively. Since the resistor Rs is included in both diodes DPI and DIN, there are correspondingly two noise sources.

Both diodes DPI and DIN are considered noisy (if the parameter Noise is set to "YES"). Shot noise and flicker noise (Kf, Af, Ffe) generated by the DC current flowing through the diodes is characterized by the following spectral density:

In the preceding expressions, k is Boltzmann's constant, T is the operating temperature in Kelvin, q is the electron charge, Kf, Af, and Ffe are model parameters, f is the simulation frequency, and
f is the noise bandwidth.

The RC sub-circuit is considered noiseless.

Equivalent Circuit

  1. J. Kyhälä and M. Andersson, "An Advanced PIN-diode Model," Microwave Journal, September 2005, pp. 206-212.
  2. R.H. Caverly, N.V. Drozdovski, L.M. Drozdovskaia and M.J. Quinn, "SPICE Modeling of Microwave and RF Control Diodes," Proc. 43rd IEEE Midwest Symp., August 8-11, 2000.
  3. A.G.M. Strollo, "A New SPICE Model of Power P-I-N Diode Based on Asymptotic Waveform Evaluation," IEEE Transactions on Power Electronics, Vol. 12, No. 1, pp. 12-20, January 1997.

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