eldo_user

Examples
Example 12—Overshoot Extraction of an Opamp
Netlist Explanation
.PARAM pCX=0.2P
CX M8D OUT pCX ! COMPENSATION CAP.
CL OUT 0 1p ! LOAD CAP.
The above lines specifies the circuit has a capacitive load, and a compensation capacitor is set
so that phase margin is approx. 45°.
.CONNECT INN OUT
The above line specifies the opamp is connected in follower configuration.
.OPTION tuning=vhigh
The above line sets the simulator accuracy to very high.
.tran 1n 1000n
The above line specifies that a transient analysis should be performed on the circuit lasting
1000ns with a plotting increment of 1ns.
VDD VDD 0 1.65V
VSS VSS 0 -1.65V
VB BIAS 0 0.95V
VINP INP 0 PULSE -0.9 0.9 10n 1n 1n 500n 1000n
The above lines specify the power supplies, bias, and transient input (a step function on the
positive input).
.PLOT TRAN V(INP) V(OUT)
The above lines request voltage plots of the input and output signals.
.EXTRACT TRAN LABEL=povershoot abs((MAX(V(OUT)) - 0.9)/0.9)*100
.EXTRACT TRAN LABEL=novershoot abs((MIN(V(OUT)) + 0.9)/0.9)*100
The above lines extract the overshoot in as a percentage.
.OPTION numdgt=3
.PRINTFILE TRAN extract(povershoot) extract(novershoot)
+ file=opamp_overshoot.txt
The .PRINTFILE statement is used to print results in tabular format to an ASCII file,
opamp_overshoot.txt. The measurements from the .EXTRACT statements are printed to the
file. The NUMDGT option is specified to limit the number of decimals used when printing
numbers.
1302
Eldo® User's Manual, 15.3