ARF475FL

APT’s products are covered by one or more of U.S.patents 4,895,810 5,045,903 5,089,434 5,182,234 5,019,522

5,262,336 6,503,786 5,256,583 4,748,103 5,283,202 5,231,474 5,434,095 5,528,058 6,939,743 and foreign patents. US and Foreign patents pending. All Rights Reserved.

128MHz Test amplifier

Po = 900W @150V

3ms pulse 10% Duty Cycle

Notes:

The value of L1 must be adjusted as the supply voltage is

changed to maintain resonance in the output circuit. At

128MHz its value changes from approximately 40nH at

100V to 30nH at 150V.

With the 50

Ω drain-to-drain load, the duty cycle above

100V must be reduced to insure power dissipation is

within the limits of the device. Maximum pulse length

should be 100mS or less. See transient thermal

impedance, figure 5.

Peak Output Power vs. Vdd and Duty Cycle

0

100

200

300

400

500

600

700

800

900

80

100

120

140

160

0

0.2

0.4

0.6

0.8

1

1.2

Drain Supply Voltage Vdd

Duty Cycle

Po Watts

Max

J1

Vdd

+

+

-

L3

DUT

TL3

TL4

TL5

TL6

L2

L1

C1

C2

C3

C4

C5

C11

TL1

TL2

J2

T3

Vg1

Vg2

C6

C7

C8

C9

T2

T1

R1

R4

R2

R3

C1 25pF poly trimmer

C2 750pF ATC 700B

C3-4 2200pF NPO 500V chip

C5-10 10nF 500V chip

C11 1000uF 250V electroytic

L1 30nH 1.5t #18 enam .375" dia

L2 680nH 12t #24 enam .312" dia

L3 2t #20 on Fair-Rite 2643006302 bead, ~ 2uH

R1-2 3.1

Ω : 3 parallel 22Ω 1W 2512 SMT

R3-4 2.2k

Ω 1/4W axial

T1 1:1 balun 50

Ω coax on Fair-Rite 2843000102 core

T2 4:1 25

Ω coax on 2843000102 Fair-Rite balun core

T3 1:1 coax balun RG-303 on 2861006802 Fair-Rite core

TL1-2 Printed line L= 0.75" w =.23"

TL3-6 Printed line L= 0.65" w =.23"

0.23" wide stripline on FR-4 board is ~ 30

Ω Zo

C10

HAZARDOUS MATERIAL WARNING

The white ceramic portion of the device between leads and mounting surface is beryllium oxide, BeO. Beryllium oxide dust is toxic when inhaled. Care must be taken during

handling and mounting to avoid damage to this area. These devices must never be thrown away with general industrial or domestic waste.

ARF475

.225

.225

.050

.050

.325

.570

.320

.125dia

4 pls

.125R

4 pls

SS

SS

D1

G1

G2

D2

1.500

.300

.200

.005

.040

1.250

Thermal Considerations and Package Mounting:

The rated power dissipation is only available when the package

mounting surface is at 25°C and the junction temperature is 175°C.

The thermal resistance between junctions and case mounting sur-

face is 0.3°C/W. When installed, an additional thermal impedance

of 0.1°C/W between the package base and the mounting surface is

typical. Insure that the mounting surface is smooth and flat. Ther-

mal joint compound must be used to reduce the effects of small sur-

face irregularities. Use the minimum amount necessary to coat the

surface. The heatsink should incorporate a copper heat spreader to

obtain best results.

The package design clamps the ceramic base to the heatsink. A

clamped joint maintains the required mounting pressure while al-

lowing for thermal expansion of both the base and the heat sink.

Four 4-40 (M3) screws provide the required mounting force. T = 6

in-lb (0.68N-m).