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Performance degradation of OQPSK using HMC520ALC4.

Question asked by Mr.yoo on Jun 12, 2017
Latest reply on Jun 12, 2017 by mthahira

Hello everyone.


I am testing an OQPSK transmitter using the HMC520ALC4.
The modulation method is a direct modulation method.
I and Q signals are made in the FPGA and I and Q are input to IQMIXER (HMC520ALC4) with a 90 degree phase difference.
The MER(Modulation Error Ratio) of the I and Q signals generated by the FPGA is approximately 28 dB. When this signal passes through IQMIXER (HMC520ALC4), MER(Modulation Error Ratio) decreases by  about 24dB.

 

The IQ signal passes through IQMIXER (HMC520ALC4), the MER(Modulation Error Ratio) decreases by  about 4 dB.

 

I wonder if it is common for MER(Modulation Error Ratio) to get worse when passing IQMIXER.
I wonder if there is a way to improve the MER(Modulation Error Ratio) of the signal passed through IQMXIER.

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