ATF-38143-TR1 Avago Technologies US Inc., ATF-38143-TR1 Datasheet - Page 9

• Manufacturer Part Number: ATF-38143-TR1
• Description: TRANSISTOR,HEMT,N-CHAN,4.5V V(BR)DSS,90mA I(DSS),SOT-343R
• Manufacturer: Avago Technologies US Inc.

Specifications of ATF-38143-TR1

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Noise Parameter Applications Information
F
ments while the F
lated. The F
figure measurements made at 16 different impedances
using an ATN NP5 test system. From these measure-
ments, a true F
true minimum noise figure of the device when the
device is presented with an impedance matching net-
work that transforms the source impedance, typically
50Ω, to an impedance represented by the reflection
coefficient Γ
network that will present Γ
associated circuit losses. The noise figure of the com-
pleted 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 F
only when the device is presented with Γ
reflection coefficient of the matching network is other
than Γ
greater than F
NF = F
Where R
the optimum reflection coefficient required to produce
F
impedance actually presented to the device. The losses
min
min
values at 2 GHz and higher are based on measure-
and Γ
min
o
, then the noise figure of the device will be
n
+ 4 R
/Z
s
o
Zo (|1 + Γ
is the reflection coefficient of the source
min
o
is the normalized noise resistance, Γ
. The designer must design a matching
min
n
values are based on a set of 16 noise
min
mins
based on the following equation.
is calculated. F
|Γ
below 2 GHz have been extrapo-
s
o
|
– Γ
2
) (1 – Γ
o
o
to the device with minimal
|
2
s
|
2
)
min
represents the
o
. If the
o
min
is
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 match-
ing networks are related to the Q of the components
and associated printed circuit board loss. Γ
fairly low at higher frequencies and increases as fre-
quency is lowered. Larger gate width devices will typi-
cally have a lower Γ
width devices.
Typically for FETs, the higher Γ
impedance much higher than 50Ω is required for the
device to produce F
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 muilti-layer 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 F
noise figure of nearly 0.65 dB. A discussion concerning
calculated and measured circuit losses and their effect
on amplifier noise figure is covered in Avago Applica-
tion 1085.
min
of the device creating an amplifier
min
o
as compared to narrower gate
. At VHF frequencies and even
9
o
usually infers that an
o
is typically