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參數(shù)資料
| 型號(hào)： | ATF-551M4-TR1G |
| 廠商： | AGILENT TECHNOLOGIES INC |
| 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)： | 13/23頁 |
| 文件大?。?/td> | 183K |
| 代理商： | ATF-551M4-TR1G |
20
R3 =
V
DD – V
ds
(1)
p
Ids + IBB
V
DD is the power supply voltage.
Vds is the device drain to source
voltage.
Ids is the desired drain current.
IBB is the current flowing
through the R1/R2 resistor
voltage divider network.
The value of resistors R1 and R2
are calculated with the following
formulas.
R1 =
Vgs
(2)
p
I
BB
R2 =
(V
ds – V
gs) R1
(3)
p
Vgs
Example Circuit
V
DD = 3V
Vds = 2.7V
Ids = 10 mA
Vgs = 0.47V
Choose I
BB to be at least 10X the
maximum expected gate leakage
current. I
BB was conservatively
chosen to be 0.5 mA for this
example. Using equations (1), (2),
and (3) the resistors are calcu-
lated as follows
R1 = 940
R2 = 4460
R3 = 28.6
Active Biasing
Active biasing provides a means
of keeping the quiescent bias
point constant over temperature
and constant over lot to lot
variations in device dc perfor-
mance. The advantage of the
active biasing of an enhancement
mode PHEMT versus a depletion
mode PHEMT is that a negative
power source is not required. The
techniques of active biasing an
enhancement mode device are
very similar to those used to bias
a bipolar junction transistor.
An active bias scheme is shown
in Figure 2.
INPUT
C1
C2
C3
C7
L1
R5
R6
R7
R3
R2
R1
Q2
Vdd
R4
L2
L3
L4
Q1
Zo
C4
C5
C6
OUTPUT
Figure 2. Typical ATF-551M4 LNA with Active
Biasing.
R1 and R2 provide a constant
voltage source at the base of a
PNP transistor at Q2. The con-
stant voltage at the base of Q2 is
raised by 0.7 volts at the emitter.
The constant emitter voltage plus
the regulated V
DD supply are
present across resistor R3.
Constant voltage across R3
provides a constant current
supply for the drain current.
Resistors R1 and R2 are used to
set the desired Vds. The combined
series value of these resistors also
sets the amount of extra current
consumed by the bias network.
The equations that describe the
circuit’s operation are as follows.
V
E = V
ds + (Ids R4)
(1)
R3 =
V
DD – V
E
(2)
p
Ids
V
B = VE – VBE
(3)
V
B =
R1
V
DD
(4)
p
R1 + R2
V
DD = I
BB (R1 + R2)
(5)
Rearranging equation (4)
provides the following formula
R2 =
R
1 (V
DD – VB)
(4A)
p
VB
and rearranging equation (5)
provides the follow formula
R1 =
V
DD
(5A)
9
I
BB
(1 +
V
DD – VB
)p
V
B
Example Circuit
V
DD = 3 V
Vds = 2.7 V
Ids = 10 mA
R4 = 10
V
BE = 0.7 V
Equation (1) calculates the
required voltage at the emitter o
the PNP transistor based o
desired Vds and Ids throug
resistor R4 to be 2.8V. Equation
(2) calculates the value of resistor
R3 which determines the drain
current Ids. In the example
R3=18.2
. Equation (3) calculates
the voltage required at the junc-
tion of resistors R1 and R2. This
voltage plus the step-up of the
base emitter junction determines
the regulated Vds. Equations (4)
and (5) are solved simultaneously
to determine the value of resistors
R1 and R2. In the example
R1=4200
and R2 =1800.
R7 is chosen to be 1 k
. This
resistor keeps a small amount of
current flowing through Q2 to help
maintain bias stability. R6 is
chosen to be 10 K
. This value of
resistance is high enough to limit
Q1 gate current in the presence of
high RF drive levels as experi-
enced when Q1 is driven to the
P1dB gain compression point. C7
provides a low frequency bypass to
keep noise from Q2 effecting the
operation of Q1. C7 is typically
0.1
F.
Maximum Suggested Gate Current
The maximum suggested gate
current for the ATF-551M4 is
1 mA. Incorporating resistor R5
in the passive bias network or
resistor R6 in the active bias
network safely limits gate current
to 500
A at P1dB drive levels.
In order to minimize component
count in the passive biased
amplifier circuit, the 3 resistor
bias circuit consisting of R1, R2,
and R5 can be simplified if
desired. R5 can be removed if R1
is replaced with a 5.6K
resistor
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| 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 |
| ATF-58143-BLKG | 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-BLKG | 制造商:Avago Technologies 功能描述:RF Bipolar Transistor |
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