design Rf circuit in ADS problem

linuscomex said:

hi.
one of the most important thing to design low noise amplifier is stability.there are a lot of methods for stabilized amplifier, for example, add the resistor to drain of HEMT transistor but I can't understand why use microstrip line to connect the resistor to an amplifier? and how design microstrip length?

for clearly see an image.

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BigBoss said:

This is an equivalent distributed model of a layout and interconnections of an amplifier (?) that has been stabilized by a resistor and a capacitor.So, they are simply interconnections in order to simulate that amplifier more accurately.
W,L and substrate dimensions are given, you don't need anything else..

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volker@muehlhaus said:

I think these small line lengths represent the SMD pad/component dimensions.

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linuscomex said:

all transmission line has an impedance in a specific frequency that effect on all of the circuit.

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linuscomex said:

how design w,l of line?

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volker@muehlhaus said:

When line length is very short compared to wavelength, impedance transformation equations give Zin = Zload for any value of Zline.







As written before: these line segments are not calculated for a specific line impedance. They describe the required pad & interconnect dimensions, so they depend on your SMD footprint size.

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linuscomex said:

yes, but w,l of smd foot print Will affect on impedance , noise ,gain and .... of circuit.

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