Good day,
I'm using virtuoso 6.1.6 and I'm trying to simulate IRR of a receiver front-end. The IQ separation is generated by a RF hybrid coupler(transmission-line based, using mtline component in analoglib) and IQ recombining is realized at baseband (BB) using another BB hybrid coupler (ideal S-parameter defined n-port). I think I'm clear with the difference between PAC and PXF. I got different result using PAC and PXF as following:
Let's assume LO frequency is 15GHz, both IQ channels are driven by the same LO.
(1) PAC: a. set "PAC magnitude=1" at input RF source and PAC simulation frequency at 15G~16G, looking at final combined output (BB) at -1harmonic sideband (0~1GHz), the gain is A1.
b. set "PAC magnitude=1" at input RF source and PAC simulation frequency at 14G~15G, looking at final combined output (BB) at -1harmonic sideband (1GHz~0), the gain is A2.
IRR= A1-A2, this result shows around 40dB IRR.
(2)PXF: Set PXF node at final combined output (BB) and PXF simulation frequency at 0~1GHz, looking at "1" and "-1" sideband PXF transfer function of input source. Their difference is the IRR, but the simulation result only shows <1dB IRR.
When I used S-parameter defined n-port as RF hybrid coupler as well, this inconsistence disappeared so I wondered if this is caused by the transmission line. BTW, Harmonic Balance is chosen for PSS engine as I found shooting engine doesn't work with transmission line. If I'm wrong about this, please point out.
I'm not sure whether I descript my question well, if you have anything that want we to clarify, please feel free.
Thank you,
Yang
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