In linear analog operation VIN will be held near ground except for small signal excursions away from ground. RL2 where gm1 and gm2 are the transconductances of the two transistors. The first line is always the title and the last non-blank line is always .end . It is this line that reports the transconductances of each transistor. The middle half of the input file describes the connection of circuit elements and sources.
Digital behavior is the extreme of large signal behavior.
The model definition below names a model bjt of the type npn and with specific parameters. This definition makes use of line continuation. The operating point information gives the DC bias voltages for all the nodes in the circuit and the current through every voltage source. A customary trick to measure current is to insert a voltage source whose voltage is zero. This does not hinder simulated performance, but the circuit will simulate slightly slower, since there's more in it.