Can eight digital inputs (at 20-Mhz) output to 160-Mhz? Does a multiplexer work for this? Thanks for your answers.
it depends on the digital inputs. If each individual digital channel is the same digital protocol (frames). Then you can apply a process called "Muxing". This we take your 8 paralleled lines of data, then apply it to a device called a parallel to serial shift register (74HC589 for example) then you frame it out back to you eight data lines. These of IC's are based off the device known as a flip-flop. See: http://www.electronics-tutorials.ws/sequential/seq_5.html as they go into great detail in construction and operation.