6
Application and Usage
Biasing and Operation
The recommended quiescent DC bias condition for opti-
mum e ciency, performance, and reliability is Vd=5 volts
with Vg set for Id=650mA. Minor improvements in per-
formance are possible depending on the application. The
drain bias voltage range is 3 to 5V. A single DC gate sup-
ply connected to Vg will bias all gain stages. Muting can
be accomplished by setting Vg and /or Vg to the pinch-o
voltage Vp.
An optional output power detector network is also pro-
vided. The di erential voltage between the Det-Ref and
Det-Out pads can be correlated with the RF power emerg-
ing from the RF output port. The detected voltage is given
by :
V = (Vref - Vdet) - Vofs
where Vref is the voltage at the DET_R port, Vdet is a voltage
at the DET_O port, and Vofs is the zero-input-power o set
voltage. There are three methods to calculate : Vofs
1) Vofs
can be measured before each detector measurement
(by removing or switching o the power source and
measuring Vref - Vdet). This method gives an error due to
temperature drift of less than 0.01dB/50C.
2) Vofs can be measured at a single reference temperature.
The drift error will be less than 0.25dB.
3) Vofs can either be characterized over temprature and
stored in a lookup table, or it can be measured at two
temperatures and a linear t used to calculate Vofs at
any temperature. This method gives an error close to
the method #1.
The RF ports are AC coupled at the RF input to the rst
stage and the RF output of the nal stage. No ground
wired are needed since ground connections are made
with plated through-holes to the backside of the device.
Assembly Techniques
The chip should be attached directly to the ground plane
using either a ux less AuSn solder perform or electrically
conductive epoxy[1]. For conductive epoxy, the amount
should be just enough to provide a thin llet around the
bottom perimeter of the die. The ground plane should
be free of any residue that may jeopardize electrical or
mechanical attachment. Caution should be taken to not
exceed the Absolute Maximum Rating for assembly tem-
perature and time.
Thermo-sonic wedge bonding is the preferred method
for wire attachment to the bond pads. The RF connections
should be kept as short as possible to minimize inductance.
Gold mesh[2] or double-bonding with 0.7mil gold wire is
recommended. Mesh can be attached using a 2mil round
tracking tool and a too force of approximately 22grams
with an ultrasonic power of roughly 55dB for a duration of
76±8mS. A guided wedge at an ultrasonic power level of
64dB can be used for the 0.7mil wire. The recommended
wire bonding stage temperature is 150±2˚C.
The chip is 100m thick and should be handled with care.
This MMIC has exposed air bridges on the top surface.
Handle at the edges or with a custom collet (do not pick
up die with vacuum on die center).
This MMIC is also static sensitive and ESD handling pre-
cautions should be taken.
For more detailed information, see Avago Application
Note 54 “GaAs MMIC ESD, Die Attach and Bonding Guide
lines.”
Notes:
1. Ablebond 84-1 LM1 silver epoxy is recommended.
2. Buckbee-Mears Corporation, St. Paul, MN, 800-262-3824