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The chip wll be damaged in this operating condition?

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xbtxbt

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Hi,all!
I use WJ amplifier SCG002.The main parameters of this chip are (1、absolute maximum RF input power(continuous):+12dBm.2、Absolute maximum junction temperature:+250 degree.3、Package:SOT89.4、DC supply:3.9V/45mA. 5、operating case temperature:-40 to +85 degree.6、thermal resistance:about 150 degree/Watt).
In my circuit,The amplifier may have to endure a dangerous input pulse of +25dBm with the port impedance of 50 ohm,lasting 100ns.The dangerous pulse will not be repeated in a long time.I wonder if the amplifier would be damaged in this operating condition.TKS!
 

vfone

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Is a hard to get the right answer, because the manufacturer specifies only the maximum continuous input power.
If the duty cycle of the input signal is high, definitely the level of the signal could be higher before braking the temperature of the junction.
But there is not only temperature that could damage the junction, is also the breakdown voltage that can occur before temperature breakdown.
 

xbtxbt

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vfone said:
Is a hard to get the right answer, because the manufacturer specifies only the maximum continuous input power.
If the duty cycle of the input signal is high, definitely the level of the signal could be higher before braking the temperature of the junction.
But there is not only temperature that could damage the junction, is also the breakdown voltage that can occur before temperature breakdown.

I have contact WJ technology support, and they can't give my any clear answer,either.I think I should insert a limiter at the front of the chip,but it's hard to seek a low power limiter diode as to -10~0dBm power with a requestion of broadband frequency.
 

biff44

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You can test the amplifier to see if it survives. Test the room temp gain first. Then heat it up to max operating temperature, and then pump a +25 dBm pulse 100 nS long and 1 second off time for the next week. Then test the room temp gain again to see if it drifted. More than 1 dB of drift and you have probably damaged the amplifier.

You can make a limiter with a shottky detector driving it.
 

xbtxbt

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biff44 said:
You can test the amplifier to see if it survives. Test the room temp gain first. Then heat it up to max operating temperature, and then pump a +25 dBm pulse 100 nS long and 1 second off time for the next week. Then test the room temp gain again to see if it drifted. More than 1 dB of drift and you have probably damaged the amplifier.

You can make a limiter with a shottky detector driving it.


Thank you very much for your kindness!
I want to conduct the experiment of run-out.But it's really complicated.
I'm now search for a method of your next suggestion.I just wonder how to handle that question when designing those instruments such as spectrum analyzer and network analyzer in which I believe there must be a set of circuit for treating the transiently adding power tuned by the user. For a best sensitivity,the gain of the internal circuit of spectrum analyzer and network analyzer will be set to be as high as possible by the controller program with the pre-amplifiers truned on.Then,perhaps,a big power input rush into the spectrum analyzer receiver just because the operator wanted to test a big power signal.The spectrum analyzer would not be damaged,either.How can they do this???
Using a PIN limiter diode drived by a shottky diode is a good idea.But I think it's hard to find some diodes able to build a circuit whose threshold power is below than -20dBm.
 

pewang

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If your input power at the spectrum anlyzer exceed the specify max power, what ever it puls type or cw type, the instrument will gone immediately. Because this damage is elecrical breakdown not thermal accumulated.
For the WJ device, I guess it's a HBT device. Basicaly, HBT can't be drive to (P1dB-gain)+6dB imput power.
 

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