AD8376ACPZ-R7 datasheet(13/24 Pages) AD

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AD8376

Rev. A | Page 13 of 24

APPLICATIONS

BASIC CONNECTIONS

Figure 36 shows the basic connections for operating the

AD8376. A voltage between 4.5 V and 5.5 V should be applied

to the supply pins. Each supply pin should be decoupled with at

least one low inductance, surface-mount ceramic capacitor of

0.1 μF placed as close as possible to the device.

The outputs of the AD8376 are open collectors that need to be

pulled up to the positive supply with 1 μH RF chokes. The differ-

ential outputs are biased to the positive supply and require ac-

coupling capacitors, preferably 0.1 μF. Similarly, the input pins

are at bias voltages of about 2 V above ground and should be ac-

coupled as well. The ac-coupling capacitors and the RF chokes are

the principle limitations for operation at low frequencies.

To enable each channel of the AD8376, the ENBA or ENBB pin

must be pulled high. Taking ENBA or ENBB low puts the

channels of the AD8376 in sleep mode, reducing current

consumption to approximately 5 mA per channel at ambient.

SINGLE-ENDED-TO-DIFFERENTIAL CONVERSION

The AD8376 can be configured as a single-ended input to

differential output driver, as shown in Figure 34. A 150 Ω

resistor in parallel with the input impedance of input pin

provides an impedance matching of 50 Ω. The voltage gain and

the bandwidth of this configuration, using a 150 Ω load,

remains the same as when using a differential input.

Using a single-ended input decreases the power gain by 3 dB

and limits distortion cancellation. Consequently, the second-

order distortion is degraded. The third-order distortion remains

low to 200 MHz, as shown in Figure 35.

0.1µF

37.5Ω

150Ω

1/2

AD8376

1µH

150Ω

A0 TO A4

1µH

+5V

VCM

0.1µF

50Ω

Figure 34. Single-Ended-to-Differential Conversion

Featuring ½ of the AD8376

–60

–65

–70

–75

–80

–85

–90

–95

–100

150

100

FREQUENCY (MHz)

HD2

HD3

Figure 35. Harmonic Distortion vs. Frequency of

Single-Ended-to-Differential Conversion

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