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参数资料
型号： ATF-541M4-BLK
厂商： AGILENT TECHNOLOGIES INC
元件分类： 小信号晶体管
英文描述： X BAND, Si, N-CHANNEL, RF SMALL SIGNAL, HEMFET
封装： 1.4 MM X 1.2 MM, 0.7 MM HEIGHT, MINIATURE PACKAGE-4
文件页数： 5/16页
文件大小： 166K
代理商： ATF-541M4-BLK
13
The value of resistors R1 and R2
are calculated with the following
formulas
R1 =
V
gs
(2)
p
I
BB
R2 =
(V
ds – V
gs) R1
(3)
p
V
gs
Example Circuit
V
DD = 5 V
Vds = 3 V
Ids = 60 mA
Vgs = 0.58 V
Choose I
BB to be at least 10X the
maximum expected gate leakage
current. I
BB was chosen to be
2 mA for this example. Using
equations (1), (2), and (3) the
resistors are calculated as follows
R1 = 290
R2 = 1210
R3 = 32.3
Active Bias
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-541M4 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 V
ds. 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
V
B
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 = 5 V
V
ds = 3 V
I
ds = 60 mA
R4 = 10
V
BE = 0.7 V
Equation (1) calculates the re-
quired voltage at the emitter of the
PNP transistor based on desired
V
ds and Ids through resistor R4 to
be 3.6V. Equation (2) calculates the
value of resistor R3 which deter-
mines the drain current I
ds. In the
example R3=23.3
. Equation (3)
calculates the voltage required at
the junction of resistors R1 and R2.
This voltage plus the step-up of the
base emitter junction determines
the regulated V
ds. Equations (4)
and (5) are solved simultaneously
to determine the value of resistors
R1 and R2. In the example
R1=1450
and R2 =1050. Resis-
tor 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 experienced
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-541M4 is
2 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 4.7K
resistor
and if R2 is replaced with a 27K
resistor. This combination should
limit gate current to a safe level.
PCB Layout
A suggested PCB pad print for
the miniature, Minipak 1412
package used by the ATF-541M4
is shown in Figure 3.
相关PDF资料
PDF描述
ATF-541M4-TR1 X BAND, Si, N-CHANNEL, RF SMALL SIGNAL, HEMFET
ATF-541M4-BLKG X BAND, Si, N-CHANNEL, RF SMALL SIGNAL, HEMFET
ATF-541M4-TR2 X BAND, Si, N-CHANNEL, RF SMALL SIGNAL, HEMFET
ATF-541M4-TR2 C BAND, Si, N-CHANNEL, RF SMALL SIGNAL, HEMFET
ATF-541M4-BLK C BAND, Si, N-CHANNEL, RF SMALL SIGNAL, HEMFET
相关代理商/技术参数
参数描述
ATF-541M4-BLK 制造商:Avago Technologies 功能描述:RF BIPOLAR TRANSISTOR
ATF-541M4-TR1 功能描述:射频GaAs晶体管 Transistor GaAs Single Voltage RoHS:否 制造商:TriQuint Semiconductor 技术类型:pHEMT 频率:500 MHz to 3 GHz 增益:10 dB 噪声系数: 正向跨导 gFS（最大值/最小值）:4 S 漏源电压 VDS: 闸/源击穿电压:- 8 V 漏极连续电流:3 A 最大工作温度:+ 150 C 功率耗散:10 W 安装风格: 封装 / 箱体:
ATF-541M4-TR2 功能描述:射频GaAs晶体管 Transistor GaAs Single Voltage RoHS:否 制造商:TriQuint Semiconductor 技术类型:pHEMT 频率:500 MHz to 3 GHz 增益:10 dB 噪声系数: 正向跨导 gFS（最大值/最小值）:4 S 漏源电压 VDS: 闸/源击穿电压:- 8 V 漏极连续电流:3 A 最大工作温度:+ 150 C 功率耗散:10 W 安装风格: 封装 / 箱体:
ATF55143 制造商:AGILENT 制造商全称:AGILENT 功能描述:Agilent ATF-55143 Low Noise Enhancement Mode Pseudomorphic HEMT in a Surface Mount Plastic Package
ATF-55143 制造商:Avago Technologies 功能描述:MOSFET RF HEMT SOT-343
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