kelly
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Hi Aaron,
Thanks for your post, you ansered one of my questions regarding the bandpass nature of the input impedance.
I guess I have two things I want to ask for your opnions.
1. Yes, you are right, the mixer output is cross coupled. So if you looking in from the input, you see the average conductance + load capacitance? If you do, for a small capacitance such that the average conductance + load capacitance is say around 200ohms, you can put a shunt 50 ohms at the input so now the input impedance is dominated by 50 ohms. As the load capacitances increases, you will need to increase the 50ohms to get closer to 50 ohms up to the point where the average conductance + load capacitance is real small so the shunt resistor doesn't do much. Am I think this right?
2. Back to the input impedance. So I get a bandpass responce as you said. Now I have a CLC filter at the output of the mixer. When I look at the input impedance, I still get the bandpass around the input frquenct, now it's much narrower. In addtion, I also get one more valley and hill on each side. (so the shape goes up and down 3 rimes around the input frequency and tapers out to a lower values on both side) I know for sure it's due to the inductor. if I disconnect the inductor, then I just get the normal bandpass. Do you think this is due to how the CLC filter process the input signal? But the CLC is just a low pass filter though......Don't undestand why if would change the shape of the input impedance like that.
Any comments are welcomed. Thanks.
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