7

Biasing and Operation

The AMMC-6241 is normally biased with a positive sup-

the 100pF bypass capacitor as shown in Figure 21. The

recommended supply voltage is 3 V. It is important to

place the bypass capacitor as close to the die as possible.

No negative gate bias voltage is needed for the AMMC-

6241. Input and output matching are achieved on-die,

therefore no other external component is required

besides one 100pF bypass capacitor for the main sup-

ply. The input and output are DC-blocked with internal

coupling capacitors.

No ground wires are needed because all ground connec-

tions are made with plated through-holes to the backside

of the device.

Refer the Absolute Maximum Ratings table for allowed

DC and thermal conditions.

Assembly Techniques

The backside of the MMIC chip is RF ground. For mi-

crostrip applications the chip should be attached directly

to the ground plane (e.g. circuit carrier or heatsink) using

For best performance, the topside of the MMIC should be

brought up to the same height as the circuit surrounding

it. This can be accomplished by mounting a gold plate

metal shim (same length and width as the MMIC) under

the chip which is of correct thickness to make the chip

and adjacent circuit the same height. The amount of

epoxy used for the chip and/or shim attachment should

be just enough to provide a thin fillet around the bottom

perimeter of the chip or shim. The ground plan should

be free of any residue that may jeopardize electrical or

mechanical attachment.

The location of the RF bond pads is shown in Figure

12. Note that all the RF input and output ports are in a

Ground-Signal-Ground configuration.

RF connections should be kept as short as reasonable

to minimize performance degradation due to undesir-

able series inductance. A single bond wire is normally

sufficient for signal connections, however double bond-

ing with 0.7 mil gold wire or use of gold mesh is recom-

mended for best performance, especially near the high

end of the frequency band.

Thermosonic wedge bonding is preferred method for

wire attachment to the bond pads. Gold mesh can be at-

tached using a 2 mil round tracking tool and a tool force

of approximately 22 grams and a ultrasonic power of

roughly 55 dB for a duration of 76 +/- 8 mS. The guided

wedge at an untrasonic power level of 64 dB can be used

for 0.7 mil wire. The recommended wire bond stage tem-

perature is 150 +/- 2C.

Caution should be taken to not exceed the Absolute

Maximum

Notes:

1. Ablebond 84-1 LM1 silver epoxy is recommended.

2. Eutectic attach is not recommended and may jeopardize reliability

of the device.

Figure 18. AMMC-6241 Simplified Schematic

RFout

RFin

VD1

VD2