Application note

TS507

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3.2

In-the-loop-compensation technique

The second technique is called the in-the-loop-compensation technique, because the

additional components (a resistor and a capacitor) used to improve the stability are inserted

in the feedback loop (see Figure 30).

Figure 30.

In-the-loop compensation schematics

This compensation method allows, by a good choice of compensation components, to

compensate the original pole (caused by the capacitive load), and thus to improve stability.

The main drawback of this circuit is the reduction of the output swing, because the isolation

resistor is in the signal path.

Table 6 helps you to choose the best compensation components for different ranges of load

Table 6.

Best compensation components for different load capacitor ranges in

Load capacitor

range

Minimum gain

1.

Parameter guaranteed by design at 25°C.

Minimum phase

margin

(degree)(1)

10 pF to 100 pF

1

250

17

55

100 pF to 1 nF

1

250

16

42

1 nF to 10 nF

1

630

11

27