Datasheet
SLOS156E − MAY 1996 − REVISED SEPTEMBER 2006
25
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TYPICAL CHARACTERISTICS
− Unity-Gain Bandwidth − kHz
UNITY-GAIN BANDWIDTH
vs
LOAD CAPACITANCE
C
L
− Load Capacitance − pF
B
1
60
10
40
0
80
50
70
20
30
10
1
10
2
10
3
10
4
10
5
T
A
= 25°C
10
6
Figure 53
APPLICATION INFORMATION
driving large capacitive loads
The TLV2211 is designed to drive larger capacitive loads than most CMOS operational amplifiers. Figures 51
and 52 illustrate its ability to drive loads up to 600 pF while maintaining good gain and phase margins
(R
null
= 0).
A smaller series resistor (R
null
) at the output of the device (see Figure 54) improves the gain and phase margins
when driving large capacitive loads. Figures 51 and 52 show the effects of adding series resistances of 500
Ω and 1000 Ω. The addition of this series resistor has two effects: the first is that it adds a zero to the transfer
function and the second is that it reduces the frequency of the pole associated with the output load in the transfer
function.
The zero introduced to the transfer function is equal to the series resistance times the load capacitance. To
calculate the improvement in phase margin, equation 1 can be used.
∆φ
m1
+ tan
–1
ǒ
2 ×π×UGBW × R
null
× C
L
Ǔ
∆φ
m1
+ improvement in phase margin
UGBW + unity-gain bandwidth frequency
R
null
+ output series resistance
C
L
+ load capacitance
(1)
Where :