3 Routing Topologies for Transmitters With Multiplexer Switches

Broadly, there are two ways to organize the connections between the transmitters and the mux switches. This section shows an example system with two 16CH transmitters and two 32CH multiplexers, but the concepts and routing topologies outlined here can be extended and applied more broadly.

The first is an interwoven input style (Figure 3-1), referring to how the multiplexer switch inputs are routed. Each adjacent switch input connects to sequential transmitter outputs. The transmitter outputs repeated to connect the additional multiplexer IC and hence interweaving with connections to the previous. The advantage is that on the output side, the routing from the multiplexer to the transducer is optimized for orderly connections. Additionally, only one clock cycle is required to update the state of all switch channels during scan, resulting in a faster system switching time.

The second is an interwoven output style (Figure 3-2) referring to how the multiplexer switch outputs are routed. Each adjacent switch output connects to disparate transducer elements and interweave as a result. The advantage is that on the input side, the routing from the transmitter to the multiplexer is optimized for short connections between switches. Additionally, because only half of the channels on each multiplexer can be active at a time, power dissipation is divided evenly between each IC.

Table 3-1 compares the tradeoffs between the interwoven input and interwoven output routing approaches.