Hello,
I have an application where I’d like to use the RFMD2081 chip to produce a binary phase shift keying [BPSK] output. When reviewing the electrical specifications of the data sheet I have seen the I & Q input 3 dB bandwidth is 100 MHz typical. This is enough bandwidth for the signal I intend to use [1, 4] MHz.
The input voltage on the I & Q input is listed as “Differential with 1.3 V input DC bias”. The “typical” differential voltage is listed as 1 Vpk-pk in the electrical spec. [sheet 2].
For the BPSK modulation my plan is to tie the Q inputs to DC bias with no differential signal applied… For the I input I plan to bias the pin with a resistor network to achieve a 1.3 V at the pins. I then plan to AC couple a square wave and connect to the 1.3 V midpoint to achieve the 1 Vpk-pk. The inverse would be connected on the negative side…
1.) I have experience with RF, but have question regarding internal mixer. Will the IQ modulator mixer be able to handle an AC coupled square wave added to the 1.3 VDC bias? Specifically 1.8 V on positive cycle and 0.8 V on negative cycle to be appled to I_P, while 0.8 V on positive cycle and 1.8 V on negative cycle to be applied to I_N. My experience with mixers has been in taking 2x RF signals and mixing them together to produce one output.
I have a couple more questions… Is there an evaluation board + schematic for this particular chip? I could use to compare to what I have in my design.
Thanks in advance,
Spencer