Transient analysis in ADS

[Mnkmii]

Hi
I design a negative resistance oscillator in ADS it works correctly with ideal TL with transient analysis.
But when i change ideal to microstrip line there is no oscillation in output even with a pulse current to the base
@BigBoss
I appreciate if you can help me

 

[BigBoss]

So you have maybe used lossy transmission lines like FR-4@10 GHz.
Your simulation technique is also wrong. You have to check negative resistance the active part only (oscillator core) without resonator circuit.
Additional to this, this configuration is not appropriate oscillator that woks @10 GHz. Base Grounded all Microstrip Line configuration will be more appropriate.
Research more for higher frequency microstrip lines oscillators.

 

[Mnkmii]

So you have maybe used lossy transmission lines like FR-4@10 GHz.
Your simulation technique is also wrong. You have to check negative resistance the active part only (oscillator core) without resonator circuit.
Additional to this, this configuration is not appropriate oscillator that woks @10 GHz. Base Grounded all Microstrip Line configuration will be more appropriate.
Research more for higher frequency microstrip lines oscillators.

I follow the gonzales book theory design for this oscillator and i use ro5880 for microstrip lines and in this book he said that if you need better output power it is better to use common emitter configuration the reason why i used this config was this. And i found in some documents of ADS in high freq and microstrip line notice that transient analysis is not good for oscillators and it does not show the oscillation when you use microstrips in high freq and its better to use HB and nyquist simulation to check if there is any oscillation or not.

 

[BigBoss]

I suggest you try other configuration such as Common Base with Transmission Line.
Transient simulation can work -if the oscillator truly oscillates- if you tie a step single step excitation source to the circuit in order to wake up the network.
Because initial state of the network can be inappropriate for starting up of oscillation. There are tricky methods in oscillator design.

 

[Mnkmii]

I suggest you try other configuration such as Common Base with Transmission Line.
Transient simulation can work -if the oscillator truly oscillates- if you tie a step single step excitation source to the circuit in order to wake up the network.
Because initial state of the network can be inappropriate for starting up of oscillation. There are tricky methods in oscillator design.

Where should i add these excitations?

 

[BigBoss]

Where should i add these excitations?

Try to connect to the base.