LO_P and LO_N ports DC connected to each other

Question I would like to use the Johanson 1720BL15B0050 balun as an input to the RF and LO differential port. The 1720BL15B0050 has a "DC feed" point connected to the two differential ports which I will use for the RF biasing. On the LO side, this DC path on the differential ports is not accepted, but I could fit an RF choke to isolate the port. Would it be acceptable if the LO_P and LO_N ports are DC connected to each other? Answer The ADL5382 has an internal DC level that it is biased at and needs to be maintained. For this reason, if you are using the ADL5382 evaluation board the DC blocks are already in place on the differential inputs. If you are not using the ADL5382 evaluation board and decide to use the Johanson balun then you can put a DC cap to GND on the DC feed pin of thebalun.

ADL5382: output filter design

Question In ADL5382 application circuit at I/Q output there is a low pass filter with cut-off 1.9MHz. I want to change this filter to 20MHz cut-off. Kindly give me a circuit with values for the 20MHz cut-off filter and also send me an application note to calculate the same. Answer For LPF with 20MHz cut-off, you can consider following circuits and component values, please see attachment. Sorry, we don't have an application note document for filter design. You may consider using following links. Active filter design tool: http://www.analog.com/designtools/en/filterwizard/#/type Filter design tool: http://www.nuhertz.com/