AN2995

Possible configurations

Doc ID 15840 Rev 1

5/13

Figure 4.

High-pass Sallen-Key configuration

3.3

Differential amplifier configuration

The differential amplifier configuration allows the subtraction of two voltages.

The transfer function is: Vout = Vin1 ((Z8+Z4)/Z8 * Z5/(Z1+Z5)) - Z4/Z8*Vin2.

Choosing Z8 = Z1 and Z4 = Z5 gives:

Vout = (Vin1-Vin2)*Z4/Z8

Z6, Z7, Z9, Z12 and Z14 must be "not connected". Z2, Z3 and Z13 must be shorted.

Figure 5.

Differential amplifier configuration

3.4

The goal of this compensation technique is to stabilize an amplifier configuration with a

capacitive load. This compensation is called in-loop because the additional components

(Z13 and Z4) used to improve the stability are inserted in the feedback loop.

Z5, Z6 and Z8 must be "not connected". Z1, Z2 and Z3 must be shorted.

Vout

Vin1

Z9

Z4

Z1

Z2

Z5

Z6

AM04503

Vout

Vin2

Z8

Z4

Z5

Z1

Vin1

AM04504

a.

More information on compensation methods can be found in application note AN2653: Operational amplifier stability

compensation methods for capacitive loading applied to TS507 (see Table 2: Document references).