Yigit Yalcinkaya
Newbie level 5
Dear Edabord Subscriptions,
I designed a negative resistance oscillator in the X band with a microstrip transmission line resonator. When I simulate the oscillator, I used Microwave Office. I ensured K, B, and Mu1 instability conditions at X oscillation frequency using Default Linear and APLAC Linear. But other frequencies also have instability. I created negative resistance and zero reactance at X frequency. But I besides observed negative resistance and zero reactance before X frequency. I want to say this point Y frequency. There wasn't any instability at the Y frequency. I trusted this. I simulated the oscillators at Harmonic Balance (HB) using OSCAPROBE. I observed oscillation only X frequency. Later, I simulated the oscillator using AXIEM. I achieved oscillation nearly X frequency and nearly the same power (S11). Lastly, I observed oscillations Voltage-Time along a few thousand nanoseconds using APLAC Trans. The oscillation signal wasn't show damping or grow-up. It had stable oscillation at a steady state.
Then, I produced my oscillator. But I couldn't produce Via. I produce only drills into PCB. After, I filled the solder in via. Before I filled the RF Vias, I inserted any tiny wire at RF active Vias. But top and bottom ground Vias are made by only solder. By the way, the laser LPKF burned too much RF lines and footprints. I had to fill it with solder. I was careful with Ft, Fmax and SRF. But my RF Choke hasn't shielded at its top.
Result:
When I measured my device, I achieved oscillation at X/3 frequency. My power was the same according to HB.
My question:
How can I explain this shift in frequency? I need to academic paper or book for reference. I know every solder and line adds inductive effects. I followed your old posts. I skimmed through Troubleshooting Analog Circuits.
I suspect other instability frequencies although satisfying the negative resistance condition and instability condition at only one frequency. I had known that stability arrange adding a resistor at the end of the device from my supervisors, Gonzalez, and Les Besser. For this reason, I designed the again oscillator. In this case, my oscillation frequency is equal to Z according to HB. My negative resistance condition is (Z - k). Z is in the C band. k is a few hundred megahertz. I measured the oscillation frequency at (Z-2*k). The difference between X and X/3 is much greater than (Z-2*k).
I can't share my emp file or frequency. I want to explain this shifting frequency. The second production certainly depends on production failure. I couldn't model production failure. I need to reference but I couldn't find any refecence except Troubleshooting Analog Circuits. How can I search for this situation? Can anyone help me?
Admin:
Can this question appear only to Edabord's members, please?
Footnote:
I really liked Les Besser's stability resistance story when he was younger. It was fun reading your book.
I designed a negative resistance oscillator in the X band with a microstrip transmission line resonator. When I simulate the oscillator, I used Microwave Office. I ensured K, B, and Mu1 instability conditions at X oscillation frequency using Default Linear and APLAC Linear. But other frequencies also have instability. I created negative resistance and zero reactance at X frequency. But I besides observed negative resistance and zero reactance before X frequency. I want to say this point Y frequency. There wasn't any instability at the Y frequency. I trusted this. I simulated the oscillators at Harmonic Balance (HB) using OSCAPROBE. I observed oscillation only X frequency. Later, I simulated the oscillator using AXIEM. I achieved oscillation nearly X frequency and nearly the same power (S11). Lastly, I observed oscillations Voltage-Time along a few thousand nanoseconds using APLAC Trans. The oscillation signal wasn't show damping or grow-up. It had stable oscillation at a steady state.
Then, I produced my oscillator. But I couldn't produce Via. I produce only drills into PCB. After, I filled the solder in via. Before I filled the RF Vias, I inserted any tiny wire at RF active Vias. But top and bottom ground Vias are made by only solder. By the way, the laser LPKF burned too much RF lines and footprints. I had to fill it with solder. I was careful with Ft, Fmax and SRF. But my RF Choke hasn't shielded at its top.
Result:
When I measured my device, I achieved oscillation at X/3 frequency. My power was the same according to HB.
My question:
How can I explain this shift in frequency? I need to academic paper or book for reference. I know every solder and line adds inductive effects. I followed your old posts. I skimmed through Troubleshooting Analog Circuits.
I suspect other instability frequencies although satisfying the negative resistance condition and instability condition at only one frequency. I had known that stability arrange adding a resistor at the end of the device from my supervisors, Gonzalez, and Les Besser. For this reason, I designed the again oscillator. In this case, my oscillation frequency is equal to Z according to HB. My negative resistance condition is (Z - k). Z is in the C band. k is a few hundred megahertz. I measured the oscillation frequency at (Z-2*k). The difference between X and X/3 is much greater than (Z-2*k).
I can't share my emp file or frequency. I want to explain this shifting frequency. The second production certainly depends on production failure. I couldn't model production failure. I need to reference but I couldn't find any refecence except Troubleshooting Analog Circuits. How can I search for this situation? Can anyone help me?
Admin:
Can this question appear only to Edabord's members, please?
Footnote:
I really liked Les Besser's stability resistance story when he was younger. It was fun reading your book.
