THS4140, THS4141

HIGHSPEED FULLY DIFFERENTIAL I/O AMPLIFIERS

SLOS320E − MAY 2000 − REVISED JANUARY 2004

17

POST OFFICE BOX 655303

PRINCIPLES OF OPERATION

theory of operation (continued)

VOCM

_

+

_

+

VCC+

VIN−

VIN+

VO+

VO−

VOD= 1−0 = 1

VOD = 0−1 = −1

a

b

+1

0

+1

0

VCC−

Similar to the standard inverting amplifier configuration, input impedance of a fully differential amplifier is

implement the differential amplifier as an instrumentation amplifier. This configuration improves the input

impedance of the fully differential amplifier. The following schematic depicts the general format of

instrumentation amplifiers.

The general transfer function for this circuit is:

V

OD

V

IN1

–V

IN2

+

R

f

R

(g)

1

) 2R2

R1

_

+

_

+

_

+

THS4012

THS4012

VIN1

VIN2

R2

R1

R2

R(g)

R(g)

Rf

Rf

THS414x

Figure 32. Instrumentation Amplifier