Operating HMC641ALP4E below -40C

Question What happens if i use your HMC641ALP4E at -55°C ? I suppose that nothing happens because the storage range is -65°C and the power dissipation is near to null: isn't it? Answer The storage temperature defines the temperature range that the device can be stored for longer period of time when powered off. The AMR for HMC641ALP4E is -65C to +150C. The operating temperature defines the temperature range that one can safely operate the device. The AMR for HMC641ALP4E is -40C to +85C. The HMC641ALP4E was product characterized on the electrical and RF performances between -40C and +85C. The device will still operate at -55C but the performances may change or degrade between operating at -40C and -55C. We have not evaluated the performances at -55C, and would recommend the customer to fully evaluate the performances if they intend to operate below -40C.

Layout Recommendations

Question We seem to be getting at least 10dB less isolation on ports, do you have any layout recommendations? Answer 1. Increase the via count underneath the package bottom.2. Route RF transmission line away from each other.3. Reduce transmission line width and ground gap (this may require stack-upchange for 50ohm impedance) so the distance between RF transmission lines isincreased and vias can be added between RF transmission lines.4. Connect NC pins to GND. You should change your board design to make it similar to our HMC641ALP4Eevaluation board layout shown below.