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One additional information; when i connect isolator between two filters, signal shape improves. Therefore either i need to connect isolator between filters or need a certain length of cable.
If i place 10 ohms resistor, how can i calculate voltage drop between resistor terminals since the amplifier will not work at 5V anymore and current drawing will not be same.
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But without external cavity filter, LNA and helical filter work fine. Connecting two cavity filters in series...
The problem is when the filter(helical) is placed before LNA, the signal distorts because before multicoupler, the customer use the one more external cavity filter (I don't know why). Therefore multicoupler's filter and external filter are cascaded and this cause distortion of signal (Certain...
Hello guys,
We are designing multicouplers which consist of LNA, power divider and cavity filter. When LNA is connected before filter, it usually fails, the amplifier PSA4-5043 breaks down. The reason of failing might be presence of too much of other band's signals in the area which cause LNA...
i tried the setup using signal generator and spectrum analyzer as you said. I am using PSA4-5043+ amplifier at 10 MHz and 400 MHz where S11=-2.23 dB and S11=-11.63 dB respectively. No dramatic change at spectrum analyzer. I did not try whether it is oscillating or not.
I want to thank you all for your answers. I have one more question about S parameters and it is also related to matching topic. When i look at the S-parameter of amplifiers something caught my attention. As the return loss(S11) get worse outside of the amplifier's working frequency band, the...
I tried your recommendation, when i put 3 db or 6 db attenuator it works just fine and the length of the cable does not affect the gain but how can do that without attenuator and why is it working with attenuator?
I am using combline filter and i did not get the ratios you mentioned. One interesting thing about the design, when i touch to the rf output of the LNA on PCB with my finger, LNA jumps to max gain but i cannot cut my finger and leave it on PCB :)
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But the case is when i use some other...
Hello guys,
I am trying to measure the gain of the LNA with a BPF using VNA. Below you see two block diagrams indicated as figure 1 and figure 2. In figure 1 band pass filter is in series with LNA and it is connected to LNA with arbitrary length of coax. In this diagram the length of the coax...
Isn't it the main feature of the BDA to work bidirectionally? We use a full duplex system. If we have to switch off one of the amplifier depending on Tx or Rx, it means that we don't have to use duplexer or any filter.
Hello guys,
I am trying to design a bidirectional amplifier system (BDA). In the figure below i drew the block diagram of the system. I used 2 duplexer with 4 cavity each. 4 cavities for Tx (2 at the i/p of LNA and 2 at the o/p of LNA) and 4 cavities for Rx overall. 2 cavities have at least 60...
First, I want to thank you my friend for your answer. Actually, I know about S-parameters, using smith chart and impedance matching techniques. However, we have not covered the amplifier design in RF frequency domain in university (It was a master course). Although, I am familiar with the...
Hello guys,
I am trying to design an amplifier using TAV1-331+ transistor that will operate at 10 MHz. Since I am fresh graduate engineer, I am having difficulties in design. Although, in the datasheet of the transistor it is indicated that it works at 50 ohm (but not internally matched), I...
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