Hello,
We want to run it in single ended mode, we have 2.4 GHz carrier and RF signal going to the LOP port and RFP port, respectively.
The LON and RFN ports, as per the data sheet, are terminated with a 100 pF capacitor and the IP and QP signals are taken and fed into an LNA. We supplied 5VDC to VPOS and connected its respective ground to GND and GND1 on the eval board. When we look at the I and Q signals, its pretty much just noise near 0V. We also tried toggling the enable switch and in both positions got the same result.
The data sheet says that the eval board is configured for single ended output (p.34), but doesn't mention anything about the output impedance. From page 3, it says these pins have an output impedance of 25 ohms per pin. Also on p.34 (T2x, T4x), there is a description which includes the TCM9-1, which states "converts a differential high impedance IF output to a single-ended output. When loaded with 50 Ω, this balun presents a 450 Ω load to the device." So I'm confused as to whether I need to have a matching network if connecting to a LNA with 50 ohm input.
Another questions is regarding the 25 ohm single ended input impedance of the RFIP and LOIP (as shown in Figure 84 oh p. 25). Is the eval board "configured" to interface with a 50 ohms?
Any help is greatly appreciated.