FIG. 3A depicts an example of a receive portion of the system. Various embodiments include an isolation switch 210 between SMA input 202 and termination resistor 212. Isolation switch 210 can be implemented as a FET bus switch. Termination resistor 212 at the input of level shifter 214 is used to avoid transmission line reflections and can be approximately a ?50 ohm pull-down resistor. Note any current regulating circuitry or resistor can be implemented as resistor devices, one or more metal-oxide-semiconductor field-effect (MOSFET) or FET transistors, or other logic. Termination resistor 212 is not in a signal path during transmission from SMA port 202 because during signal transmission (described later), level shifter 214 is isolated and disconnected from the transmit path.
