AN2653

Stability in voltage follower configuration

7/22

To remove this instability and work with higher capacitive loads, many compensation

methods exist, and this application note examines some of them. By adding zeroes and

poles to the loop gain, stability can be improved.

However, compensation components have to be chosen carefully. A compensation scheme

can indeed improve stability, but can also lead the system to instability, depending on the

choice of component values. Similarly, a compensation configuration can work for a specific

load, but modifying this load can affect stability.

Figure 11.

Input and output signals measured

with grounded input

Figure 12.

Input and output signals measured

for an AC input signal

Voltage Follower Configuration -

Output Signal with Input Grounded

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0.08

0.00

0.50

1.00

1.50

2.00

Time (μs)

Output Signal

Input Signal

TS507 :

Vcc = 5 V

Vicm = 2,5 V

T = 25 °C

RL = 10 kΩ

CL = 550pF

Voltage Follower -

Input and Output Signals

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0

100

200

300

400

500

Time (μs)

Output Signal

Input Signal

TS507 :

Vcc = 5 V

Vicm = 2,5 V

T = 25 °C

RL = 10 kΩ

CL = 550 pF