I am reviewing the HMC856 eval board schematic on page 12 of the HMC856 data sheet. I am trying to figure out how to interface the control (B0-B4) to LVTTL (1.8, 2.5 or 3.3V) control system. Is it possible?
One way to do is connect positive ports B0-B4 to a fixed voltage with a resistance, say 1.2k to GND and connect transistor switches to negative ports(B0~B4) with 2.7kohms each. Transistor switches can either be open or short to Vee. This way (B0-B4) change state. LVTTLs can drive switch transistors.
If you supply shift the part between 3.3V and GND, and if LVTTLs can supply enough current, you wouldnt need interfacing transistors/level shifters. The RF signal though should be AC couple in that case.
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