Slew rate

In the electronics is as slew rate , the rising rate, slope or the maximum rise or fall speed of the output voltage of an amplifier or driver circuit , especially a operational amplifier , respectively.

Effect of the slew rate  (green) on the transmission of a square pulse

definition

The slew rate is the maximum steepness of the edge of the output voltage if there is a square-wave signal at the input that completely modulates the amplifier (large-signal response): ${\displaystyle U_{\mathrm {out} }(t)}$

${\displaystyle \mathrm {SR} =\max \left(\left|{\frac {dU_{\mathrm {out} }(t)}{dt}}\right|\right)}$

In data sheets , the slew rate is given in volts per microsecond . The relationship to the large-signal limit frequency of an amplifier is given by the derivative  d U / d t . A sinusoidal voltage :

${\displaystyle \mathrm {U} (t)={\hat {U}}\sin(2\pi ft)}$

has the greatest slope at the zero crossing : ${\displaystyle \mathrm {U'} }$

${\displaystyle \max \left(\left|\mathrm {U'} \right|\right)=\mathrm {U'} (t=0)=\left|2\pi f{\hat {U}}\cos(2\pi ft)\right|_{(t=0)}=2\pi f{\hat {U}}}$

The slew rate required is therefore proportional to the signal amplitude and frequency . That is, an amplifier may transmit a large amplitude signal less correctly than a small signal. In data sheets for operational amplifiers, both the slew rate (see also large-signal behavior ) and the limit or transit frequency (describes the small-signal behavior ) are therefore specified. ${\displaystyle U}$ ${\displaystyle f}$

See also

• Rise and fall time