REV. 0

AD8350

–9–

Figure 30 shows how the AD8350 input can be matched for a

single-ended drive. The unused input is ac-coupled to ground

using a low impedance (i.e., high value) capacitance. The S-

Parameters for this configuration are shown in Tables III and

IV. These values assume a single-ended source impedance of

50

Ω and a differential load impedance of 50 Ω. As in the case

of a differential drive, a simultaneous conjugate match must be

performed to correctly match both input and output.

8

7

6

5

1

2

3

4

AD8350

–

ENBL

(+5V)

C2

0.1 F

C2

C2

0.001 F

C1

L2

L1

Figure 30. Matching Circuit for Single-Ended Drive

Evaluation Board

Figure 31 shows the schematic of the AD8350 evaluation board

as it is shipped from the factory. The board is configured to

allow easy evaluation using single-ended 50

Ω test equipment.

The input and output transformers have a 4-to-1 impedance

ratio and transform the AD8350’s 200

Ω input and output

impedances to 50

Ω. In this mode, 0 Ω resistors (R1 and R4)

are required.

To allow compensation for the insertion loss of the transform-

ers, a calibration path is provided at Test In and Test Out. This

consists of two transformers connected back to back.

To drive and load the board differentially, transformers T1 and

T2 should be removed and replaced with four 0

Ω resistors

(0805 size); Resistors R1 and R4 (0

Ω) should also be removed.

This yields a circuit with a broadband input and output imped-

ance of 200

Ω. To match to impedances other than this, match-

ing components (0805 size) can be placed on pads C1, C2, C3,

C4, L1 and L2.

8

7

6

5

1

2

3

4

AD8350

–

C5

0.1 F

L1

(OPEN)

L2

(OPEN)

C3

0.001 F

C2

0.001 F

C4

0.001 F

1

2

3

A

B

SW1

61

R2

0

C1

0.001 F

R1

0

T1: TC4-1W

(MINI CIRCUITS)

IN–

IN+

R3

0

6

T2: TC4-1W

(MINI CIRCUITS)

R4

0

OUT–

OUT+

16

T4: TC4-1W

(MINI CIRCUITS)

TEST OUT

61

T3: TC4-1W

(MINI CIRCUITS)

TEST IN

1

Figure 31. AD8350 Evaluation Board