I'm a bit confused about AD8306.Can this chip control the output amplitude?Can it be used as an AGC amplifier?
The AD8306 is not a stand alone AGC amplifier.
The AD8306 can be used in an analog AGC loop as a power detector, wherein it senses the output power of a VGA and RSSI output controls the VGA's gain pin. You would have to design the AGC loop according to the specifications of the VGA, most likely scaling the RSSI voltage and possibly inverting the RSSI slope, i.e. make it negative, so that the AGC loop polarity is correct. Note, inverting the RSSI slope will depend on the VGA's available slope(s).
We are looking into this. We will get back to you soon.
Thank you very much for receiving your reply.Since my chip of AD is using AD9430 .I hope my chip of AD can work normally. And My frequency range of transmission is 20M~50M. If I want to use AD8306,can you give me a reference on the chip of VGA? Can you provide me with a rough plan,please? I really need your help. Thanks again!
I still have a question, if my input range is -62dBm~-1dBm, then zoom in through AD8306, and finally I can enter the AD9430 chip.Is there any problem with such a plan,please?I saw the chip datasheet that the maximum output voltage in LIMTING AMPLIFIER is 1.25V. Does it mean hat by setting when my input is -1dBm, my output can reach 1.25V(11.94dBm)?
I hope to get your reply as soon as possible.Thanks very much!
I need to know your application and specifications before recommending anything:
Note that the limited amplifiers output is a square wave. What are you attempting to do with the sampled limited output? Are you trying to detect the phase of the signal?
The output should be a square-wave over most of the AD8306's input range due to the large amount of gain in the limiting amplifier chain. Limiter output Vpp is set by the RLIM resistor (see figure 22 in the datasheet).
Thank you very much for receiving your reply.
I want to do a receiving device.My input modulated signal(BPSK) range is -62dBm~-1dBm, and my frequency range of transmission is 20M~50M.My plan is that the signal goes through AD8306 to the AD9430 chip.But I want to ensure that AD9430 can receive a complete signal.I'm not sure if this idea is reasonable.OR Should I build an AGC loop?
I see, you are detecting changes in phase. The AD8306 limiter amps should do this fine for the power levels you indicate above.
Can you help me see if this connection is correct in the picture? I just hope that AD9430 can detect the correct signal waveform.The signal can maintain the correct frequency and amplitude.Thanks very much!
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