In designing each compensator, the following system characteristics hold true:

•*LM* = Log magnitude, base 10

•Cross-over frequency of open-loop Bode
*LM* plot

• Phase margin of open-loop Bode phase plot

• Time constant, s

• Damping ratio

The open-loop Bode frequency response can be used to approximate closed-loop system behavior, provided the open-loop frequency response satisfies three conditions:

• The gain at low frequencies is relatively high for low steady-state errors

• The gain at high frequencies is relatively low for disturbance attenuation

• The slope of the Bode plot is approximately

When the above conditions are approximately satisfied, the following correlations are valid: