SLOS156E − MAY 1996 − REVISED SEPTEMBER 2006

TLV2211, TLV2211Y

Advanced LinCMOS RAILTORAIL

MICROPOWER SINGLE OPERATIONAL AMPLIFIERS

25

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

TYPICAL CHARACTERISTICS

UNITY-GAIN BANDWIDTH

vs

LOAD CAPACITANCE

CL − Load Capacitance − pF

60

10

40

0

80

50

70

20

30

101

10 2

10 3

10 4

10 5

TA = 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

(Rnull = 0).

A smaller series resistor (Rnull) 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 2 ×π × UGBW × R

null ×

C

L

∆φ

m1 + improvement in phase margin

UGBW

+ unity-gain bandwidth frequency

R

null + output series resistance

C

L + load capacitance

(1)

Where :