The URC model is derived from a model proposed by L. Gertzberrg in 1974. The model is accomplished by a subcircuit type expansion of the URC line into a network of lumped RC segments with internally generated nodes. The RC segments are in a geometric progression, increasing toward the middle of the URC line, with K as a proportionality constant. The number of lumped segments used, if not specified for the URC line device, is determined by the following formula:
2 | R C |(K-1)| | _ _ 2 log|F 2 J L |-----| | max | L L | K | | N = ------------------------------ log K
The URC line is made up strictly of resistor and capacitor segments unless the ISPERL parameter is given a nonzero value, in which case the capacitors are replaced with reverse biased diodes with a zero-bias junction capacitance equivalent to the capacitance replaced, and with a saturation current of ISPERL amps per meter of transmission line and an optional series resistance equivalent to RSPERL ohms per meter.
name | parameter | units | default | example
|
K | Propagation Constant | - | 2.0 | 1.2
|
FMAX | Maximum Frequency of interest | Hz | 1.0G | 6.5Meg
|
RPERL | Resistance per unit length | Z/m | 1000 | 10
|
CPERL | Capacitance per unit length | F/m | 1.0e-15 | 1pF
|
ISPERL | Saturation Current per unit length | A/m | 0 | -
|
RSPERL | Diode Resistance per unit length | Z/m | 0 | -
|