ADL5561

Rev. B | Page 15 of 24

INPUT AND OUTPUT INTERFACING

The ADL5561 can be configured as a differential input to

differential output driver, as shown in Figure 32. The differential

broadband input is provided by the ETC1-1-13 balun transformer,

and the two 34.8 Ω resistors provide a 50 Ω input match for

the three input impedances that change with the variable gain

strapping. The input and output 0.1 μF capacitors isolate the

VCC/2 bias from the source and balanced load. The load must be

200 Ω to provide the expected ac performance (see the Specifications

section and the Typical Performance Characteristics section).

3.3V

VIP2

VIP1

VIN1

VIN2

A

B

AC

R2

0.1µF

ETC1-1-13

0.1µF

R1

0.1µF

0.1µF

NOTES

AND INPUT B TO BOTH VIN1 AND VIN2.

2

2

Figure 32. Differential-Input-to-Differential-Output Configuration

Table 4. Differential Termination Values for Figure 32

Gain (dB)

R1 (Ω)

R2 (Ω)

6

28.7

28.7

12

33.2

33.2

15.5

40.2

40.2

The differential gain of the AD5561 is dependent on the source

impedance and load, as shown in Figure 33.

VIP2

VIP1

VIN1

VIN2

0.1µF

0.1µF

2

2

AC

0.1µF

0.1µF

Figure 33. Differential Input Loading Circuit

The differential gain can be determined using the following

shown in Table 5.

L

L

IN

V

R

R

R

A

+

×

=

10

400

(1)

Gain (dB)

6

200

12

100

15.5

66.7

Single-Ended Input to Differential Output

The ADL5561 can also be configured in a single-ended input

to differential output driver, as shown in Figure 34. In this

configuration, the gain of the part is reduced due to the

application of the signal to only one side of the amplifier. The

strappable gain values are listed in Table 6 with the required

terminations to match to a 50 Ω source using R1 and R2. Note

that R1 must equal the parallel value of the source and R2. The

input and output 0.1 μF capacitors isolate the VCC/2 bias from

the source and the balanced load. The performance for this

configuration is shown in Figure 11, Figure 14, and Figure 20.

VIP2

VIP1

VIN1

VIN2

A

B

AC

R2

0.1µF

0.1µF

0.1µF

3.3V

+

R1

NOTES

AND INPUT B TO VIN1.

AND INPUT B TO VIN2.

VIP1 AND VIP2 AND INPUT B TO BOTH VIN1 AND VIN2.

0.1µF

2

2

Figure 34. Single-Ended Input to Differential-Output Configuration

Table 6. Single-Ended Termination Values for Figure 34

Gain (dB)

R1 (Ω)

R2 (Ω)

5.6

27

60

11.1

29

69

14.1

30

77

The single-ended gain configuration of the ADL5561 is dependent

on the source impedance and load, as shown in Figure 35.

VIP2

VIP1

VIN1

VIN2

AC

R2

0.1µF

0.1µF

0.1µF

0.1µF

+

R1

2

2

Figure 35. Single-Ended Input Loading Circuit