欢迎访问ic37.com |
会员登录 免费注册
发布采购

HSMS-2827-TR1G 参数 Datasheet PDF下载

HSMS-2827-TR1G图片预览
型号: HSMS-2827-TR1G
PDF下载: 下载PDF文件 查看货源
内容描述: 表面贴装射频肖特基势垒二极管 [Surface Mount RF Schottky Barrier Diodes]
分类和应用: 二极管射频
文件页数/大小: 14 页 / 202 K
品牌: AGILENT [ AGILENT TECHNOLOGIES, LTD. ]
 浏览型号HSMS-2827-TR1G的Datasheet PDF文件第5页浏览型号HSMS-2827-TR1G的Datasheet PDF文件第6页浏览型号HSMS-2827-TR1G的Datasheet PDF文件第7页浏览型号HSMS-2827-TR1G的Datasheet PDF文件第8页浏览型号HSMS-2827-TR1G的Datasheet PDF文件第10页浏览型号HSMS-2827-TR1G的Datasheet PDF文件第11页浏览型号HSMS-2827-TR1G的Datasheet PDF文件第12页浏览型号HSMS-2827-TR1G的Datasheet PDF文件第13页  
9
Sampling Applications  
Note that θ , the thermal resis-  
Diode Burnout  
jc  
The six lead HSMS-282P can be  
used in a sampling circuit, as  
shown in Figure 25. As was the  
case with the six lead HSMS-282R  
in the mixer, the open bridge  
quad is closed with traces on the  
circuit board. The quad was not  
closed internally so that it could  
be used in other applications,  
such as illustrated in Figure 17.  
tance from diode junction to the  
foot of the leads, is the sum of  
two component resistances,  
Any Schottky junction, be it an RF  
diode or the gate of a MESFET, is  
relatively delicate and can be  
burned out with excessive RF  
power. Many crystal video  
receivers used in RFID (tag)  
applications find themselves in  
poorly controlled environments  
where high power sources may be  
present. Examples are the areas  
around airport and FAA radars,  
nearby ham radio operators, the  
vicinity of a broadcast band  
transmitter, etc. In such  
θ
= θ  
+ θ  
chip  
(2)  
jc  
pkg  
Package thermal resistance for  
the SOT-3x3 package is approxi-  
mately 100°C/W, and the chip  
thermal resistance for the  
HSMS-282x family of diodes is  
approximately 40°C/W. The  
designer will have to add in the  
thermal resistance from diode  
case to ambienta poor choice  
of circuit board material or heat  
sink design can make this number  
very high.  
sample  
point  
HSMS-282P  
environments, the Schottky  
diodes of the receiver can be  
protected by a device known as a  
limiter diode.[5] Formerly  
sampling  
pulse  
sampling circuit  
available only in radar warning  
receivers and other high cost  
electronic warfare applications,  
these diodes have been adapted to  
commercial and consumer  
circuits.  
Equation (1) would be straightfor-  
ward to solve but for the fact that  
diode forward voltage is a func-  
tion of temperature as well as  
forward current. The equation for  
Vf is:  
Figure 25. Sampling Circuit.  
Thermal Considerations  
The obvious advantage of the  
SOT-323 and SOT-363 over the  
SOT-23 and SOT-142 is combina-  
tion of smaller size and extra  
leads. However, the copper  
leadframe in the SOT-3x3 has a  
thermal conductivity four times  
higher than the Alloy 42  
leadframe of the SOT-23 and  
SOT-143, which enables the  
smaller packages to dissipate  
more power.  
Agilent offers a complete line of  
surface mountable PIN limiter  
diodes. Most notably, our HSMP-  
4820 (SOT-23) can act as a very  
fast (nanosecond) power-sensitive  
switch when placed between the  
antenna and the Schottky diode,  
shorting out the RF circuit  
11600 (Vf If Rs)  
(3)  
nT  
If = IS  
e
1  
where n = ideality factor  
T = temperature in °K  
Rs = diode series resistance  
temporarily and reflecting the  
excessive RF energy back out the  
antenna.  
and IS (diode saturation current)  
is given by  
The maximum junction tempera-  
ture for these three families of  
Schottky diodes is 150°C under  
all operating conditions. The  
following equation applies to the  
thermal analysis of diodes:  
2
n
)
1
T
1
298  
4060  
e
(
)
T
298  
Is = I0  
(
(4)  
Tj = (V I + P ) θ + T  
a
(1)  
f
f
RF jc  
Equation (4) is substituted into  
equation (3), and equations (1)  
where  
T = junction temperature  
and (3) are solved simultaneously  
to obtain the value of junction  
temperature for given values of  
diode case temperature, DC  
power dissipation and RF power  
dissipation.  
j
T = diode case temperature  
a
θ
= thermal resistance  
V I = DC power dissipated  
f f  
jc  
[5] Agilent Application Note 1050, Low  
Cost, Surface Mount Power Limiters.”  
P
= RF power dissipated  
RF