TLE2027, TLE2037, TLE2027A, TLE2037A, TLE2027Y, TLE2037Y

EXCALIBUR LOW-NOISE HIGH-SPEED

PRECISION OPERATIONAL AMPLIFIERS

SLOS192 – FEBRUARY 1997

6–31

POST OFFICE BOX 655303

APPLICATION INFORMATION

input offset voltage nulling

The TLE2027 and TLE2037 series offers external null pins that can be used to further reduce the input offset

voltage. The circuits of Figure 55 can be connected as shown if the feature is desired. If external nulling is not

needed, the null pins may be left disconnected.

4.7 k

Ω

1 k

Ω

VCC +

OUT

IN –

IN +

VCC –

+

–

4.7 k

Ω

–

+

VCC –

OUT

VCC +

10 k

Ω

IN –

IN +

(a) STANDARD ADJUSTMENT

(b) ADJUSTMENT WITH IMPROVED SENSITIVITY

Figure 55. Input Offset Voltage Nulling Circuits

voltage-follower applications

The TLE2027 circuitry includes input-protection diodes to limit the voltage across the input transistors; however,

no provision is made in the circuit to limit the current if these diodes are forward biased. This condition can occur

when the device is operated in the voltage-follower configuration and driven with a fast, large-signal pulse. It

is recommended that a feedback resistor be used to limit the current to a maximum of 1 mA to prevent

degradation of the device. Also, this feedback resistor forms a pole with the input capacitance of the device.

For feedback resistor values greater than 10 k

Ω, this pole degrades the amplifier phase margin. This problem

can be alleviated by adding a capacitor (20 pF to 50 pF) in parallel with the feedback resistor (see Figure 56).

RF

–

+

VI

VO

VCC –

VCC

CF = 20 to 50 pF

Figure 56. Voltage Follower