ADMV1013-EVALZ evaluation board, I_P, I_N, Q_P, Q_N Input Impedance in I/Q mode.


I am testing the ADMV1013-EVALZ evaluation board in I/Q mode.
I connected a network analyzer to the I_P, I_N, Q_P, Q_N Input connectors and measured poor input return loss. (Single ended measurement, not differential)
The network analyzer test power is -10dBm.

1.  VCM = 0 V, Register 0x03, Bit 7 = 0, and Register 0x05, Bits[6:0] = 0x051
2.  Q_N, I_P and I_N show similar results.
In file Q_P_IRL.PNG file you can see the return loss of Q_P input port.
4.  In file Q_P_Smith.PNG file you can see the impedances of Q_P input port.

I have few questions:

1.  Why the input impedance is not 50ohm ?  (Single ended measurement, not differential).
2.  Do you have return loss and impedance plots of this EVB in I/Q mode for Q_P, Q_N, I_P and I_N input connectors ?




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