Page 18 - Issue 1 2023

ELECTRONICS

A better way to prototype RF designs,

using X-Microwave

By Jacob Ciolfi, associate central applications engineer

he typical prototyping experience for an RF design Imagine: You just finished planning your RF signal chain.
includes purchasing an evaluation (eval) board for You walk into the lab, grab the parts, and have a prototype
Teach of the components in the signal chain and using constructed on the bench in 60 minutes. You connect a single
RF cabling to string the boards together, creating a rough 12 V DC supply, a signal generator, and a spectrum analyser, and
approximation of how the signal chain would perform were it you’re taking measurements of PCB-like performance within a
built on a single production PCB after being properly laid out. decibel of your simulations the first time you power everything
This method can accrue significant insertion loss from long up. Unsatisfied with how an amplifier is performing? Ten
eval board PCB traces and extensive cabling and connectors. minutes with a hex key and you have it swapped out and are
The resulting prototype can also be frustrating and time testing your updated design.
consuming to bring online because of the specific voltage This is the prototyping experience offered by X-Microwave,
requirements of each eval board. It’s also not uncommon a modular RF prototyping platform that allows easily
for an RF part to require multiple voltages with specific modifiable signal chains to be built up in under an hour
power rail sequencing, which if violated could destroy the without any specialised tools. These signal chains are
component. Just the power and RF wires alone can create a composed of X-Microwave blocks – connectable single-IC RF
rat’s nest, and if any board needs digital control, things get boards – and there are parts in the ecosystem that support
further complicated. If the whole system doesn’t work the frequencies up to 60 GHz. The RF connections, solderless
first time you turn it on (as if!), debugging quickly degrades contacts secured by hex screws, are robust and simple to
into an exercise in patience and perseverance. Prototyping install. The signal chain is much easier to power and digitally
is a headache well known in the RF engineering world – the control than eval boards, requiring a single 12 V DC supply to the
solution to faster, easier, and more accurate prototypes is control board and either a Raspberry Pi, FPGA, or other driver
X-Microwave. of your choice. The X-Microwave modular design enables fast
signal chain edits, reduces debug time significantly, and keeps
the prototype compact, clean and portable.

The X-Microwave Solution
Engineers can use X-Microwave to get the performance of
an end-design single PCB with the prototyping speed and
modifiability of evaluation boards. An X-Microwave prototype
is made up of small, single-IC blocks that can be strung
together to create a signal chain. From amplifiers to mixers,
switches, PLLs, and VCOs, the X-Microwave ecosystem has
thousands of RF blocks available to support a variety of full
signal chains. Each individual RF block comprises a single RF IC,
either a packaged part or die, with the surrounding passives
required for optimal function and matching. X-Microwave takes
special care with the RF layout and design to ensure the device
performs as close to data sheet specifications as possible. On
each RF block, grounded coplanar waveguide traces run from
the IC to launches on the edges of the block. RF connections
are made from these launches to the neighbouring block
Figure 1: A full X-Microwave prototype, including power and digital using solderless ground-signal-ground (GSG) interconnects.
control, consisting of an FMC-XMW bridge board, an X-Microwave signal
chain, and a Raspberry Pi. These interconnects closely resemble continuous PCB traces,

EngineerIT | Issue 1 2023 | 18