Symbol Names: URC
Syntax: Uxxx N1 N2 Ncom <model> L=<len> [N=<lumps>]
N1 and N2 are the two element nodes the RC line connects, whereas Ncom is the node to which the capacitances are connected. MNAME is the model name and LEN is the length of the RC line in meters. Lumps, if specified, is the number of lumped segments to use in modeling the RC line. A guess at an appropriate number of lumps to use will be made if lumps is not specified.
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 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 | Description | Units | Default |
| K | Propagation Constant | - | 2. |
| Fmax | Maximum Frequency of interest | Hz | 1G |
| Rperl | Resistance per unit length | Ω | 1K |
| Cperl | Capacitance per unit length | F | 1e-15 |
| Isperl | Saturation Current per unit length | A | 0. |
| Rsperl | Diode Resistance per unit length | Ω | 0. |