V

=

OUT+

V

(1

)

V

(1

)+2V

b

IN+

IN

OCM

-

- b -

- b

2b

(1)

V

=

OUT-

-

b

V

(1

)+V

(1

)+2V

IN+

IN

OCM

-

- b

- b

2b

(2)

V =V

(1

)+V

- b

N

IN

OUT+

-

b

(3)

V

OCM

+V

S

V

S

R

S

R

G1

R

G2

R

F1

R

F2

+

R

T

+

-

-

b =

R

G

R +R

F

G

(4)

V =V

(1

)+V

- b

P

IN+

OUT-b

(5)

V

OCM

+V

S

V

S

R

S

R

G1

R

G2

R

F1

R

F2

+

R

T

+

-VS

-

-

V

OCM

R

G

R

G

R

F

R

F

+

+

V

P

V

N

V

OUT-

V

OUT+

V

IN+

V

IN-

-

-

THS4504

THS4505

SLOS363D – AUGUST 2002 – REVISED MAY 2008 ......................................................................................................................................................... www.ti.com

Where:

Figure 76. Application Circuit for the THS4500 and

THS4501, Featuring Single-Supply Operation with

a Ground-Referenced Input Signal

NOTE:

The equations denote the

device inputs as VN and

VP, and the circuit inputs

as VIN+ and VIN–.

Figure 77. Application Circuit for the THS4500 and

THS4501, Featuring Split-Supply Operation with

an Input Signal Referenced at the Midrail

Equation 1 to Equation 5 allow calculation of the

Figure 78. Diagram for Input Common-Mode

required input common-mode range for a given set of

Range Equations

input conditions.

The equations allow calculation of the input common-

Table 1 and Table 2 show the input common-mode

mode range requirements given information about the

range requirements for two different input scenarios,

input signal, the output voltage swing, the gain, and

an input referenced around the negative rail and an

the output common-mode voltage. Calculating the

input referenced around midrail. The tables highlight

maximum and minimum voltage required for VN and

the differing requirements on input common-mode

VP (the amplifier input nodes) determines whether or

range, and illustrate reasoning for choosing either the

not the input common-mode range is violated or not.

THS4500/1 or the THS4502/3. For signals referenced

Four equations are required. Two calculate the output

around the negative power supply, the THS4500/1

voltages and two calculate the node voltages at VN

should be chosen since its input common-mode

and VP (note that only one of these needs calculation,

range includes the negative supply rail. For all other

as the amplifier forces a virtual short between the two

situations, the THS4502/3 offers slightly improved

nodes).

distortion and noise performance for applications with

input signals centered between the power-supply

rails.

Table 1. Negative-Rail Referenced

Gain (V/V)

VIN+ (V)

VIN– (V)

VIN (VPP)

VOCM (V)

VOD (VPP)

VNMIN (V)

VNMAX (V)

1

–2.0 to 2.0

0

4

2.5

4

0.75

1.75

2

–1.0 to 1.0

0

2

2.5

4

0.5

1.167

4

–0.5 to 0.5

0

1

2.5

4

0.3

0.7

8

–0.25 to 0.25

0

0.5

2.5

4

0.167

0.389

20

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