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参数资料
| 型号： | MRF154 |
| 元件分类： | 功率晶体管 |
| 英文描述： | VHF BAND, Si, N-CHANNEL, RF POWER, MOSFET |
| 封装： | CASE 368-03, HOGPAC-2 |
| 文件页数： | 5/7页 |
| 文件大小： | 175K |
| 代理商： | MRF154 |
RF POWER MOSFET CONSIDERATIONS
MOSFET CAPACITANCES
The physical structure of a MOSFET results in capacitors
between the terminals. The metal oxide gate structure deter-
mines the capacitors from gate–to–drain (Cgd), and gate–to–
source (Cgs). The PN junction formed during the fabrication
of the RF MOSFET results in a junction capacitance from
drain–to–source (Cds).
These capacitances are characterized as input (Ciss), out-
put (Coss) and reverse transfer (Crss) capacitances on data
sheets. The relationships between the inter–terminal capaci-
tances and those given on data sheets are shown below. The
Ciss 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 operat-
ing conditions in RF applications.
Cgd
GATE
SOURCE
Cgs
DRAIN
Cds
Ciss = Cgd + Cgs
Coss = Cgd + Cds
Crss = Cgd
LINEARITY AND GAIN CHARACTERISTICS
In addition to the typical IMD and power gain data pres-
ented, Figure 5 may give the designer additional information
on the capabilities of this device. The graph represents the
small signal unity current gain frequency at a given drain cur-
rent level. This is equivalent to fT for bipolar transistors.
Since this test is performed at a fast sweep speed, heating of
the device does not occur. Thus, in normal use, the higher
temperatures may degrade these characteristics to some ex-
tent.
DRAIN CHARACTERISTICS
One figure of merit for a FET is its static resistance in the
full–on condition. This on–resistance, VDS(on), occurs in the
linear region of the output characteristic and is specified un-
der specific test conditions for gate–source voltage and drain
current. For MOSFETs, VDS(on) has a positive temperature
coefficient and constitutes an important design consideration
at high temperatures, because it contributes to the power
dissipation within the device.
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 input resistance is very high — on the order of 109 ohms
— resulting in a leakage current of a few nanoamperes.
Gate control is achieved by applying a positive voltage
slightly in excess of the gate–to–source threshold voltage,
VGS(th).
Gate Voltage Rating — Never exceed the gate voltage
rating. Exceeding the rated VGS 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.
MOUNTING OF HIGH POWER RF
POWER TRANSISTORS
The package of this device is designed for conduction
cooling. It is extremely important to minimize the thermal re-
sistance between the device flange and the heat dissipator.
Since the device mounting flange is made of soft copper, it
may be deformed during various stages of handling or during
transportation. It is recommended that the user makes a final
inspection on this before the device installation.
±0.0005″ is
considered sufficient for the flange bottom.
The same applies to the heat dissipator in the device
mounting area. If copper heatsink is not used, a copper head
spreader is strongly recommended between the device
mounting surfaces and the main heatsink. It should be at
least 1/4
″ thick and extend at least one inch from the flange
edges. A thin layer of thermal compound in all interfaces is,
of course, essential. The recommended torque on the 4–40
mounting screws should be in the area of 4 – 5 lbs.–inch, and
spring type lock washers along with flat washers are recom-
mended.
For die temperature calculations, the
temperature from a
corner mounting screw area to the bottom center of the
flange is approximately 5
°C and 10°C under normal operat-
ing conditions (dissipation 150 W and 300 W respectively).
The main heat dissipator must be sufficiently large and
have low R
θ for moderate air velocity, unless liquid cooling is
employed.
5
REV 2
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PDF描述 |
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| MRF157 | VHF BAND, Si, N-CHANNEL, RF POWER, MOSFET |
| MRF158R | UHF BAND, Si, N-CHANNEL, RF SMALL SIGNAL, MOSFET |
| MRF158R | UHF BAND, Si, N-CHANNEL, RF SMALL SIGNAL, MOSFET |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MRF154MP | 制造商:M/A-COM Technology Solutions 功能描述:RF POWER TRANSISTOR MOSFET |
| MRF1550FNT1 | 功能描述:射频MOSFET电源晶体管 LDMOS FET HI PWR TO272FN RoHS:否 制造商:Freescale Semiconductor 配置:Single 晶体管极性: 频率:1800 MHz to 2000 MHz 增益:27 dB 输出功率:100 W 汲极/源极击穿电压: 漏极连续电流: 闸/源击穿电压: 最大工作温度: 封装 / 箱体:NI-780-4 封装:Tray |
| MRF1550FT1 | 制造商:MOTOROLA 制造商全称:Motorola, Inc 功能描述:RF POWER FIELD EFFECT TRANSISTORS |
| MRF1550N | 制造商:FREESCALE 制造商全称:Freescale Semiconductor, Inc 功能描述:RF Power Field Effect Transistors |
| MRF1550NT1 | 功能描述:射频MOSFET电源晶体管 LDMOS FET HI PWR TO272FN RoHS:否 制造商:Freescale Semiconductor 配置:Single 晶体管极性: 频率:1800 MHz to 2000 MHz 增益:27 dB 输出功率:100 W 汲极/源极击穿电压: 漏极连续电流: 闸/源击穿电压: 最大工作温度: 封装 / 箱体:NI-780-4 封装:Tray |
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