ATF-331M4-BLK Avago Technologies US Inc., ATF-331M4-BLK Datasheet - Page 11

• Manufacturer Part Number: ATF-331M4-BLK
• Description: IC PHEMT LOW NOISE 2GHZ MINIPAK
• Manufacturer: Avago Technologies US Inc.

Specifications of ATF-331M4-BLK

• Transistor Type: pHEMT FET
• Frequency: 2GHz
• Gain: 15dB
• Voltage - Rated: 5.5V
• Current Rating: 305mA
• Noise Figure: 0.6dB
• Current - Test: 60mA
• Voltage - Test: 4V
• Power - Output: 19dBm
• Package / Case: 4-MiniPak (1412)
• Power Dissipation Pd: 400mW
• No. Of Pins: 4
• Peak Reflow Compatible (260 C): No
• Frequency Max: 2GHz
• Leaded Process Compatible: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

11
S and Noise Parameter Measurements
The position of the reference planes used for the
measurement of both S and Noise Parameter mea-
surements is shown in Figure 23. The reference plane
can be described as being at the center of both the
gate and drain pads.
S and noise parameters are measured with a 50 ohm
microstrip test fixture made with a 0.010" thickness
aluminum substrate. Both source pads are connected
directly to ground via a 0.010" thickness metal rib
which provides a very low inductance path to ground
for both source pads. The inductance associated with
the addition of printed circuit board plated through
holes and source bypass capacitors must be added to
the computer circuit simulation to properly model
the effect of grounding the source leads in a typical
amplifier design.
Figure 23. Position of the Reference Planes.
Noise Parameter Applications Information
The Fmin values are based on a set of 16 noise figure
measurements made at 16 different impedances using
an ATN NP5 test system. From these measurements,
a true Fmin is calculated. Fmin represents the true
minimum noise figure of the device when the device
is presented with an impedance matching network
that transforms the source impedance, typically 50Ω,
to an impedance represented by the reflection coef-
ficient Γ
Source
Pin 3
Pin 2
Gate
Reference
Plane
o
Microstrip
Transmission Lines
. The designer must design a matching
Px
Drain
Pin 4
Source
Pin 1
network that will present Γ
mal associated circuit losses. The noise figure of the
completed amplifier is equal to the noise figure of
the device plus the losses of the matching network
preceding the device. The noise figure of the device
is equal to Fmin only when the device is presented
with Γ
network is other than Γ
device will be greater than Fmin based on the follow-
ing equation.
NF = F
Where Rn/Zo is the normalized noise resistance, Γ
is the optimum reflection coefficient required to pro-
duce Fmin and Γ
source impedance actually presented to the device.
The losses of the matching networks are non-zero and
they will also add to the noise figure of the device
creating a higher amplifier noise figure. The losses of
the matching networks are related to the Q of the
components and associated printed circuit board loss.
Γ
increases as frequency is lowered. Larger gate width
devices will typically have a lower Γ
narrower gate width devices. Typically for FETs, the
higher Γ
higher than 50Ω is required for the device to pro-
duce Fmin. At VHF frequencies and even lower L Band
frequencies, the required impedance can be in the
vicinity of several thousand ohms. Matching to such
a high impedance requires very hi-Q components in
order to minimize circuit losses. As an example at
900 MHz, when air wound coils (Q>100)are used for
matching networks, the loss can still be up to 0.25 dB
which will add directly to the noise figure of the
device. Using multilayer molded inductors with Qs
in the 30 to 50 range results in additional loss over
the air wound coil. Losses as high as 0.5 dB or greater
add to the typical 0.15 dB Fmin of the device creat-
ing an amplifier noise figure of nearly 0.65 dB.
o
is typically fairly low at higher frequencies and
o
min
. If the reflection coefficient of the matching
o
+ 4 R
usually infers that an impedance much
Zo (|1 + Γ
n
s
is the reflection coefficient of the
|Γ
s
– Γ
o
|
o
2
, then the noise figure of the
) (1 - |Γ
o
|
2
o
to the device with mini-
s
|
2
)
o
as compared to
o