parallel coupled dro
时间：04-01
整理：3721RD
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Hello,
I need to repair a DRO because it doesn't oscillate. This is a DRO working from 5,4 to 5,9 GHz tunable by a screw, fed by + 5 [VDC], with parallel feedback configuration. The only information I have is that the post is placed between the two microstrip lines but its edge slightly cover the microstrip lines for 0.2 [mm] each. The post is also placed above the microstrips of 3 [mm]. The feed is coupled to the Drain of the GaAsFet (I suppose, because any stamp is placed on it!) by a feed-through and a Zener diode with 6.2 [V] of the zener voltage. The Source of the transistor is connected to a 1N4148 Diode and the diode to the ground, so that it can bias the Gate to a negative voltage and also to give instability (k<1, by the diode capacitance) to the transistor. The whole circuit is enclosed in a cavity 34X19 [mm] X 15 [mm] high. I have the knowledge of the microstrips, the pcb permettivity, the physical layout, all the features of the post , but I don't know the transistor's name. I am thinking to simulate the whole circuit (except the transistor) by HFSS in order to achieve the S parameters and the reflection coefficients on the transistor ports, so that I can replace a similar device.
Has anyone a better idea?
by
Andrea
I need to repair a DRO because it doesn't oscillate. This is a DRO working from 5,4 to 5,9 GHz tunable by a screw, fed by + 5 [VDC], with parallel feedback configuration. The only information I have is that the post is placed between the two microstrip lines but its edge slightly cover the microstrip lines for 0.2 [mm] each. The post is also placed above the microstrips of 3 [mm]. The feed is coupled to the Drain of the GaAsFet (I suppose, because any stamp is placed on it!) by a feed-through and a Zener diode with 6.2 [V] of the zener voltage. The Source of the transistor is connected to a 1N4148 Diode and the diode to the ground, so that it can bias the Gate to a negative voltage and also to give instability (k<1, by the diode capacitance) to the transistor. The whole circuit is enclosed in a cavity 34X19 [mm] X 15 [mm] high. I have the knowledge of the microstrips, the pcb permettivity, the physical layout, all the features of the post , but I don't know the transistor's name. I am thinking to simulate the whole circuit (except the transistor) by HFSS in order to achieve the S parameters and the reflection coefficients on the transistor ports, so that I can replace a similar device.
Has anyone a better idea?
by
Andrea