ADL5567ACPZN-R7 datasheet(17/24 Pages) AD

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ADL5567

Data Sheet

Rev. 0 | Page 16 of 23

INPUT AND OUTPUT INTERFACING

The ADL5567 can be configured as a differential input to differen-

tial output driver, as shown in Figure 40. The 50 Ω resistors, R1

and R2, combined with the input balun, provide a 50 Ω input match

for the 100 Ω input impedance. The input and output 0.1 μF

capacitors isolate the VCCX/2 bias from the source and balanced

load. The load equals 200 Ω to provide the expected ac perfor-

mance (see the Specifications section).

0.1µF

1:1 BALUN

50Ω

ADL5567

½ RL

50Ω

0.1µF

–

Figure 40. Differential Input to Differential Output Configuration

The differential gain of the ADL5567 is dependent on the source

impedance and load, as shown in Figure 41. The differential

gain (AV) can be determined by







500

(1)

ADL5567

0.1µF

50Ω

500Ω

5Ω

0.1µF

–

Figure 41. Differential Input Loading Circuit

Single-Ended Input to Differential Output

The ADL5567 can also be configured in a single-ended input to

differential output driver, as shown in Figure 42. In this configura-

tion, the gain of the device is reduced due to the application of the

signal to only one side of the amplifier. The input and output 0.1 μF

capacitors isolate the VCCx/2 bias from the source and the

balanced load.

The single-ended circuit configuration can be accomplished in

three steps (see Figure 42), assuming a 50 Ω RS source. First,

calculate the input impedance (RIN) of the amplifier using the

following formula:

 



















–

(2)

Thus, RIN = 91.7 Ω.

The next step is to calculate the termination of Resistor R2 (see

Figure 42). Because RS must be equal to the parallel equivalent

resistance of R2 and RIN,







Thus,

R2 = RIN × RS /(RIN − RS)

(3)

When RS = 50 Ω and RIN = 91.7 Ω, R2 = 109 Ω.

The last step is to calculate the gain path rebalancing resistor,

R1 (see Figure 42), using the following formula:







Thus, R1 = 34.0 Ω.

ADL5567

50Ω

500Ω

5Ω

0.1µF

–

Figure 42. Single-Ended Input to Differential Output Configuration

See the AN-0990 Application Note for more information on

terminating single-ended inputs. The single-ended gain

configuration of the ADL5567 is dependent on the source

impedance and load, as shown in Figure 43.

ADL5567

50Ω

500Ω

5Ω

0.1µF

34.2Ω

0.1µF

109Ω

–

Figure 43. Single-Ended Input Loading Circuit

Determine the single-ended gain (AV1) using the following two

equations:

MATCH







(4)

where RMATCH is the input resistance value that matches RS,

calculated as follows:

MATCH

































500

(5)

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