Diode

Diode #

The diode is a two-terminal semiconductor device that allows current to flow primarily in one direction. Breadpad uses the industry-standard Berkeley SPICE3 diode model for accurate simulation.

Basic Properties #

  • Terminals: 2 (Anode and Cathode)
  • SPICE Designation: D
  • Default Model: PN junction diode

Key Parameters #

Essential Parameters #

  • Saturation Current (IS): 1e-14 A - The reverse saturation current
  • Emission Coefficient (N): 1.0 - Ideality factor (1.0 for ideal diode, 1.2-2.0 for real devices)
  • Series Resistance (RS): 0 Ω - Internal resistance of the diode

Breakdown Characteristics #

  • Breakdown Voltage (BV): 100 V - Reverse voltage at which breakdown occurs
  • Current at Breakdown (IBV): 1 mA - Current when breakdown voltage is reached

Capacitance Parameters #

  • Zero-Bias Junction Capacitance (CJO): 0 F - Capacitance at zero voltage
  • Junction Potential (VJ): 1.0 V - Built-in junction potential
  • Grading Coefficient (M): 0.5 - Junction grading coefficient

Advanced Parameters #

  • Transit Time (TT): 0 s - Charge storage time constant
  • Forward-Bias Depletion Capacitance (FC): 0.5 - Coefficient for forward-bias depletion capacitance
  • Energy Gap (EG): 1.11 eV - Energy gap for temperature dependence (Silicon default)
  • Saturation Current Temperature Exponent (XTI): 3.0 - Temperature exponent for IS

Noise Parameters #

  • Flicker Noise Coefficient (KF): 0 - 1/f noise coefficient
  • Flicker Noise Exponent (AF): 1.0 - 1/f noise exponent

SPICE Netlist Format #

.MODEL D1_MODEL D (IS=1e-14 N=1.0 BV=100 IBV=0.001 RS=0)
D1 anode cathode D1_MODEL

Common Diode Types #

To simulate different diode types, adjust these parameters:

Signal Diode (1N4148) #

  • IS = 2.52e-9
  • RS = 0.568
  • N = 1.752
  • CJO = 4e-12

Power Diode (1N4007) #

  • IS = 7.02e-9
  • RS = 0.0341
  • N = 1.8
  • BV = 1000
  • IBV = 5e-6

Schottky Diode #

  • IS = 1e-8
  • N = 1.05
  • RS = 0.1
  • Lower VJ (~0.3V)

Zener Diode #

  • Standard parameters plus:
  • BV = Zener voltage
  • IBV = 1-10mA (typical)

Tips for Simulation #

  1. Convergence: If simulation has convergence issues, try increasing RS slightly (0.01-0.1 Ω)
  2. Temperature Analysis: Use XTI and EG parameters for accurate temperature sweeps
  3. Switching Circuits: Set TT parameter for accurate switching behavior
  4. RF Applications: CJO and VJ are critical for high-frequency behavior

See Also #