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stability problem of condtional amplifier?

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abdoeng

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hi all,i add resistor at drain of ATF36077 to make k>1 in all band(8-12 GHZ) but the stability still < 1 .any method to make stabilty >1
regards
 

there are two kinds of unstability:(1)the rf unstability(2)the feed DC power unstability:
the resistor in the drain only conquer the feed DC unstability,but not RF unstability,try to add a resistor in the rf chain
 

    abdoeng

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I used a similar device a while ago and the problem was stability at lower frequencies. To overcome this, add a resistor in series with gate, bypassed by a capacitor at your amplifier frequency. Should help!

Instability not necessarily occurs in your band of intest. It can occur everywhere!
 

There are several ways to stabilize the transistor:
1. add a series resistor at the gate.
2. add a parallel resistor at the gate
3. series resistor at drain
4. parallel resistor at drain
5. a feedback (drain to gate) resistor with capacitor.

and more
 

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