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參數(shù)資料
| 型號： | MRF1535NT1 |
| 廠商： | Motorola, Inc. |
| 英文描述： | RF Power Field Effect Transistors |
| 中文描述： | 射頻功率場效應(yīng)晶體管 |
| 文件頁數(shù)： | 9/16頁 |
| 文件大?。?/td> | 257K |
| 代理商： | MRF1535NT1 |
MRF1535NT1 MRF1535FNT1 MRF1535T1 MRF1535FT1
9
RF Device Data
Freescale Semiconductor
APPLICATIONS INFORMATION
DESIGN CONSIDERATIONS
This device is a common
source, RF power, N
Channel
enhancement mode, Lateral Metal
Oxide Semiconductor
Field
Effect Transistor (MOSFET). Freescale Application
Note AN211A, “FETs in Theory and Practice”, is suggested
reading for those not familiar with the construction and char-
acteristics of FETs.
This surface mount packaged device was designed pri-
marily for VHF and UHF mobile power amplifier applications.
Manufacturability is improved by utilizing the tape and reel
capability for fully automated pick and placement of parts.
However, care should be taken in the design process to in-
sure proper heat sinking of the device.
The major advantages of Lateral RF power MOSFETs in-
clude high gain, simple bias systems, relative immunity from
thermal runaway, and the ability to withstand severely mis-
matched loads without suffering damage.
MOSFET CAPACITANCES
The physical structure of a MOSFET results in capacitors
between all three terminals. The metal oxide gate structure
determines the capacitors from gate
to
drain (C
gd
), and
gate
to
source (C
gs
). The PN junction formed during fab-
rication of the RF MOSFET results in a junction capacitance
from drain
to
source (C
ds
). These capacitances are charac-
terized as input (C
iss
), output (C
oss
) and reverse transfer
(C
rss
)
capacitances on data sheets. The relationships be-
tween the inter
terminal capacitances and those given on
data sheets are shown below. The C
iss
can be specified in
two ways:
1. Drain shorted to source and positive voltage at the gate.
2. Positive voltage of the drain in respect to source and zero
volts at the gate.
In the latter case, the numbers are lower. However, neither
method represents the actual operating conditions in RF ap-
plications.
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DRAIN CHARACTERISTICS
One critical figure of merit for a FET is its static resistance
in the full
on condition. This on
resistance, R
DS(on)
, occurs
in the linear region of the output characteristic and is speci-
fied at a specific gate
source voltage and drain current. The
drain
source voltage under these conditions is termed
V
DS(on)
. For MOSFETs, V
DS(on)
has a positive temperature
coefficient at high temperatures because it contributes to the
power dissipation within the device.
BV
DSS
values for this device are higher than normally re-
quired for typical applications. Measurement of BV
DSS
is not
recommended and may result in possible damage to the de-
vice.
GATE CHARACTERISTICS
The gate of the RF MOSFET is a polysilicon material, and
is electrically isolated from the source by a layer of oxide.
The DC input resistance is very high
on the order of 10
9
— resulting in a leakage current of a few nanoamperes.
Gate control is achieved by applying a positive voltage to
the gate greater than the gate
to
source threshold voltage,
V
GS(th)
.
Gate Voltage Rating
— Never exceed the gate voltage
rating. Exceeding the rated V
GS
can result in permanent
damage to the oxide layer in the gate region.
Gate Termination
— The gates of these devices are es-
sentially capacitors. Circuits that leave the gate open
cir-
cuited or floating should be avoided. These conditions can
result in turn
on of the devices due to voltage build
up on
the input capacitor due to leakage currents or pickup.
Gate Protection
— These devices do not have an internal
monolithic zener diode from gate
to
source. If gate protec-
tion is required, an external zener diode is recommended.
Using a resistor to keep the gate
to
source impedance low
also helps dampen transients and serves another important
function. Voltage transients on the drain can be coupled to
the gate through the parasitic gate
drain capacitance. If the
gate
to
source impedance and the rate of voltage change
on the drain are both high, then the signal coupled to the gate
may be large enough to exceed the gate
threshold voltage
and turn the device on.
DC BIAS
Since this device is an enhancement mode FET, drain cur-
rent flows only when the gate is at a higher potential than the
source. RF power FETs operate optimally with a quiescent
drain current (I
DQ
), whose value is application dependent.
This device was characterized at I
DQ
= 150 mA, which is the
suggested value of bias current for typical applications. For
special applications such as linear amplification, I
DQ
may
have to be selected to optimize the critical parameters.
The gate is a dc open circuit and draws no current. There-
fore, the gate bias circuit may generally be just a simple re-
sistive divider network. Some special applications may
require a more elaborate bias system.
GAIN CONTROL
Power output of this device may be controlled to some de-
gree with a low power dc control signal applied to the gate,
thus facilitating applications such as manual gain control,
ALC/AGC and modulation systems. This characteristic is
very dependent on frequency and load line.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MRF1535NT1_06 | 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:RF Power Field Effect Transistors |
| MRF1535NT1_08 | 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:RF Power Field Effect Transistors N-Channel Enhancement-Mode Lateral MOSFETs |
| MRF1535NT1_0806 | 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:RF Power Field Effect Transistors |
| MRF1535T1 | 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:RF Power Field Effect Transistor |
| MRF154 | 功能描述:射頻MOSFET電源晶體管 RF Transistor RoHS:否 制造商:Freescale Semiconductor 配置:Single 晶體管極性: 頻率:1800 MHz to 2000 MHz 增益:27 dB 輸出功率:100 W 汲極/源極擊穿電壓: 漏極連續(xù)電流: 閘/源擊穿電壓: 最大工作溫度: 封裝 / 箱體:NI-780-4 封裝:Tray |
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