.AC Record

Requests a small signal AC analysis for the circuit. The '.' before AC must be in the first column of the record. The .AC record contains four parameters which control the AC analysis:

.AC I1, I2, F1, F2

where

• [I1] Number of frequency intervals to be calculated. If frequency spacing is not linear (see I2) then I1 is the number of intervals per frequency factor. Defaults to zero intervals (one value of frequency).
• [I2] Frequency factor. I2 = 0 or 1 results in linear spacing of the calculated frequency intervals between F1 and F2. I2 = 2 results in I1 intervals per octave. I2 = 10 results in I1 intervals per decade. I2 $\geq$ 0. Defaults to linear spacing.
• [F1] Starting frequency ($\geq$0).
• [F2] Ending frequency ( > F1).

The frequency and phase units default to Hertz and degrees. This selection can be changed to radians per second and radians on the .OPT record.

The results format of an AC analysis defaults to dB and phase. This format can be changed to either real and imaginary or magnitude and phase on the .OPT record.

Examples:

.AC 100 10.e3 20.e3 * 100 intervals from 10KHz to 20KHZ (or 10Krps to 20Krps)

.AC 50 10 1.0 100.0 * 50 pts/decade from 1. to * 100.Hz or rps.

.AC 5, 2 10.0, 40.0 * 5 pts/octave from 10 to 40 Hz or rps.

.AC 25 10 6. 6.k * 25 pts/decade from 6 to 6K Hz or rps.

; use of parameters

; sweep from fmid / 3 to fmid * 3

.par fmid 100.k

.ac 100 10 { fmid 3. / } { fmid 3. X }

;

.AC 100. * zero intervals (one point) at 100. Hz or rps.

.AC CLR * clears existing AC record. Use with * .ALTEL/.ALTGO control.