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參數(shù)資料
| 型號(hào)： | ATF-551M4-BLK |
| 元件分類： | 小信號(hào)晶體管 |
| 英文描述： | X BAND, Si, N-CHANNEL, RF SMALL SIGNAL, HEMFET |
| 封裝： | 1.40 MM X 1.20 MM, 0.70 MM HEIGHT, MINIATURE, LEADLESS PACKAGE-4 |
| 文件頁數(shù)： | 11/23頁 |
| 文件大?。?/td> | 406K |
| 代理商： | ATF-551M4-BLK |
1
Bias Networks
One of the major advantages of the enhancement
mode technology is that it allows the designer to be
able to dc ground the source leads and then merely
apply a positive voltage on the gate to set the desired
amount of quiescent drain current Id.
Whereas a depletion mode PHEMT pulls maximum
drain current when V
gs= 0 V, an enhancement mode
PHEMT pulls only a small amount of leakage current
when V
gs= 0 V. Only when Vgs is increased above Vth, the
device threshold voltage, will drain current start to flow.
At a V
ds of 2.7V and a nominal Vgs of 0.47V, the drain
current I
d will be approximately 10 mA. The data sheet
suggests a minimum and maximum V
gs over which the
desired amount of drain current will be achieved. It is
also important to note that if the gate terminal is left
open circuited, the device will pull some amount of
drain current due to leakage current creating a voltage
differential between the gate and source terminals.
Passive Biasing
Passive biasing of the ATF-551M4 is accomplished by
the use of a voltage divider consisting of R1 and R2. The
voltage for the divider is derived from the drain voltage
which provides a form of voltage feedback through the
use of R3 to help keep drain current constant. In the
case of a typical depletion mode FET, the voltage divider
which is normally connected to a negative voltage
source is connected to the gate through resistor R4.
Additional resistance in the form of R5 (approximately
10K) is added to provide current limiting for the gate
of enhancement mode devices such as the ATF-551M4.
This is especially important when the device is driven to
P1dB or Psat.
Resistor R3 is calculated based on desired V
ds, Ids and
available power supply voltage.
V
DD – Vds
I
ds + IBB
R3 =
(1)
Figure . Typical ATF-551M4 LNA with Passive Biasing.
INPUT
C1
C2
C3
L1
R4
R1
R2
Vdd
R3
L2
L3
L4
Q1
Zo
C4
C5
C6
OUTPUT
R5
ATF-551M4 Applications Information
Introduction
Avago Technologies’s ATF-551M4 is a low noise
enhancement mode PHEMT designed for use in low
cost commercial applications in the VHF through 10
GHz frequency range. As opposed to a typical depletion
mode PHEMT where the gate must be made negative
with respect to the source for proper operation, an
enhancement mode PHEMT requires that the gate
be made more positive than the source for normal
operation. Therefore a negative power supply voltage is
not required for an enhancement mode device. Biasing
an enhancement mode PHEMT is much like biasing the
typical bipolar junction transistor. Instead of a 0.7V base
to emitter voltage, the ATF-551M4 enhancement mode
PHEMT requires a nominal 0.47V potential between the
gate and source for a nominal drain current of 10 mA.
Matching Networks
The techniques for impedance matching an en-
hancement mode device are very similar to those for
matching a depletion mode device. The only difference
is in the method of supplying gate bias. S and Noise
Parameters for various bias conditions are listed in
this data sheet. The circuit shown in Figure 37 shows a
typical LNA circuit normally used for 900 and 1900 MHz
applications. Consult the Avago Technologies web site
for application notes covering specific designs and ap-
plications. High pass impedance matching networks
consisting of L1/C1 and L4/C4 provide the appropri-
ate match for noise figure, gain, S11 and S22. The
high pass structure also provides low frequency gain
reduction which can be beneficial from the standpoint
of improving out-of-band rejection.
Capacitors C2 and C5 provide a low impedance in-band
RF bypass for the matching networks. Resistors R3 and
R4 provide a very important low frequency termination
for the device. The resistive termination improves low
frequency stability. Capacitors C3 and C6 provide the
RF bypass for resistors R3 and R4. Their value should be
chosen carefully as C3 and C6 also provide a termina-
tion for low frequency mixing products. These mixing
products are as a result of two or more in-band signals
mixing and producing third order in-band distor-
tion products. The low frequency or difference mixing
products are terminated by C3 and C6. For best sup-
pression of third order distortion products based on
the CDMA 1.25 MHz signal spacing, C3 and C6 should
be 0.1 uF in value. Smaller values of capacitance will
not suppress the generation of the 1.25 MHz difference
signal and as a result will show up as poorer two tone
IP3 results.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ATF-551M4-BLK | 制造商:Avago Technologies 功能描述:Transistor |
| ATF-551M4-TR1 | 功能描述:射頻GaAs晶體管 Transistor GaAs Single Voltage RoHS:否 制造商:TriQuint Semiconductor 技術(shù)類型:pHEMT 頻率:500 MHz to 3 GHz 增益:10 dB 噪聲系數(shù): 正向跨導(dǎo) gFS（最大值/最小值）:4 S 漏源電壓 VDS: 閘/源擊穿電壓:- 8 V 漏極連續(xù)電流:3 A 最大工作溫度:+ 150 C 功率耗散:10 W 安裝風(fēng)格: 封裝 / 箱體: |
| ATF-551M4-TR2 | 功能描述:射頻GaAs晶體管 Transistor GaAs Single Voltage RoHS:否 制造商:TriQuint Semiconductor 技術(shù)類型:pHEMT 頻率:500 MHz to 3 GHz 增益:10 dB 噪聲系數(shù): 正向跨導(dǎo) gFS（最大值/最小值）:4 S 漏源電壓 VDS: 閘/源擊穿電壓:- 8 V 漏極連續(xù)電流:3 A 最大工作溫度:+ 150 C 功率耗散:10 W 安裝風(fēng)格: 封裝 / 箱體: |
| ATF-58143 | 制造商:AGILENT 制造商全稱:AGILENT 功能描述:Low Noise Enhancement Mode Pseudomorphic HEMT in a Surface Mount Plastic Package |
| ATF-58143-BLK | 制造商:AGILENT 制造商全稱:AGILENT 功能描述:Low Noise Enhancement Mode Pseudomorphic HEMT in a Surface Mount Plastic Package |
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