I am using the HMC900 as a low pass filter before inputting the signal into the HMC1197. The common mode voltage of the two devices is not compatible. The minimum common mode voltage output from the HMC900 is 1.5V (5V/2 -1), but the HMC1197 requires 0.45V common mode voltage. Is there a recommended way to shift the common mode voltage between the two devices.
DC coupling using negative supply
If AC coupling is not possible then by connecting HMC900 or HMC960 ground to a negative supply (and lowering their VDD correspondingly), the difference between the common mode voltages can be compensated. The 2.5V HMC900/960 output common mode voltage referred to a -2.05V GND, will be 0.45V at the ADC or modulator input referred to 0V ADC or modulator GND.
With this setup, the high bandwidth and low complexity of the Direct DC coupling can be maintained while using the optimum Common mode voltages for both driver and ADC or modulator (the diagram is showing a discontinued HMC ADC component HMCAD1050 which expected a 0.9V common mode voltage).
Why AC coupling is not possible? A capacity can be used to fix the common mode voltages mismatch.