Eleven T&M Functions, One Device: Liquid Instruments Introduces the “Instrument-on-Chip”

March 28, 2022 by vishvachi

With an FPGA at its heart, the Moku product series allows engineers to tap into a suite of programmable test instruments—all on a single device.

What if you could bundle multiple test and measurement (T&M) devices in one piece of hardware?

Test equipment company Liquid Instruments aims to make programmable T&M a reality with its Moku product series. The company recently announced an update that will allow its users to use three new instruments in addition to the eight test and measurement (T&M) instruments that were already available on its base model, the Moku:Go.

Moku:Go is designed to help students and engineers work on fundamental concepts of signals, radio, FIR filtering, IIR filtering, and many more.


Many T&M Devices on a Single Chip

Liquid Instruments was founded in 2014 by a group of researchers who had a background in lasers and signal processing. The co-founder, Dr. Danielle Wuchenich, who is also the company’s COO, started using an FPGA-based spectrum analyzer during her Ph.D., spurring the idea of flexible test equipment.

Liquid instruments has three products in the market: Moku:Go, Moku:Pro, and Moku:Lab. Moku:Go, the most affordable device in the Moku product range, now gives users access to a digital filter box, a FIR filter, and a lock-in amplifier. Beyond these tools, the device's pre-existing test and measurement instruments include an oscilloscope, waveform generator, logic analyzer, frequency analyzer, PID controller, datalogger, arbitrary waveform generator, and a spectrum analyzer.


Moku:Go, Moku:Pro, and Moku:Lab

From left to right, Moku:Go, Moku:Pro, and Moku:Lab


In an exclusive All About Circuits interview with Liquid Instruments, CEO Daniel Shaddock explained:

When you buy conventional test equipment, typically it already does everything that it's going to do for the rest of its life. And with our Moku products, that's not true at all. In fact, when people buy it, it does only a fraction of what it will do a few years later. For example, when people first bought the very first Moku:Lab, we only had three instruments on it. Now those same people have twelve instruments only a few years later on hardware that they've done nothing to—other than update an iPad app—and now they get all of this cool new stuff.


The Breakdown of an "Instrument-on-Chip"

The Moku series is built around an evolving trend known as instrument-on-chip (IoC) in which devices are built around powerful and real-time FPGAs. An IoC’s architecture contains four important components:

  1. A powerful DSP chip
  2. Analog/digitals inputs
  3. Analog/digital outputs
  4. An active network connection for instrument configuration

Building these devices around the FPGA gives engineers unlimited flexibility to use new test tools. While various other chips like CPUs, GPUs, and ASICs can perform fast signal processing, FPGAs have the advantage of parallel processing instruction sets, enabling the devices to efficiently perform complex DSP computations.

“Instead of Moku products being a replacement for a box, it's now a replacement for a whole rack of equipment potentially,” Shaddock explained. “And that whole rack of equipment is actually on a single chip. There are no cables and no connections. Everything is running in that FPGA.”


Basic Moku:Go specs

Basic Moku:Go specs.


The Moku combines an FPGA with a processor like a CPU to form a system-on-a-chip (SoC). A CPU competently manages the network connections and configuration functionalities while the FPGA manages the complex computations.

An FPGA-based T&M system typically has perfect noiseless digital signals. “We don’t need to re-digitize the analog signal,” Shaddock said. “An ADC can give you quantization effects and can cause non-linearities. With FPGAs we have perfect lossless digital signals with a super low latency of about 10 ns.”


Moku:Go's New "Multi-instrument Mode"

In June, Moku:Go’s users will have access to a "multi-instrument mode," which will allow an individual to deploy multiple instruments simultaneously. Users can develop a custom DSP directly on the Moku:Go’s FPGA using the Moku Cloud Compile technology. These two features were previously a success with the Moku:Pro and will soon be available on the more affordable Moku:Go. 

Liquid Instruments can sell Moku products with a base bundle of five general-purpose instruments. Alternatively, users can invest in a full-suite bundle to access all the instruments Liquid Instruments offers, along with any others the company rolls out in the future. Or, users can buy additional instruments as needed.

“If it's 3:00 a.m. and you're in the lab, and you realize you need a digital filter box, you can go on our website, type in a credit card number, and 30 seconds later, it's already running on your device,” Shaddock remarked.


Multi-instrument mode allows users to simultaenously run multiple research-grade instruments on chip.

Multi-instrument mode allows users to simultaenously run multiple research-grade instruments on chip.


With the addition of three new instruments, Moku:Go is ready to be used by students and engineers for sensitive T&M needs. A digital filter box is a tool that can be used to build an 8th-order IIR filter for noise filtering and signal amplification. The FIR filter builder can deploy FIR filters to filter noise in LTE communications. And, the lock-in amplifier can help professors teach complex labs in the field of laser frequency stabilization, RF demodulation, and software-defined radio.


Moku:Go, Moku:Pro or Moku:Lab? Which One to Choose?

Moku:Go, designed with low price point in mind, is the most basic of the Moku devices with 12-bit analog I/O channels. The input voltage range is up to ±25 V and the output range is ±5 V. Moku:Lab is a bigger and more advanced device with 200 MHz analog input bandwidth and a 300 MHz output analog bandwidth. It also has a dedicated TTL port for triggering and an additional laser lock box and phasemeter instrument integrated within this device.

Shaddock noted that Moku:Lab has been used in universities around the world for undergraduate teaching. While performance of these devices is much higher than labs need, students found this new programmable approach to test equipment so much more engaging and less intimidating, Shaddock explained.

Liquid Instruments then translated many of the popular features of Moku:Lab to Moku:Go to make testing even more accessible for prospective engineers.


Moku interface

The Moku app is designed to be intuitive, so even students can easily navigate various instruments at once.


“Conventional test equipment can turn a lot of students off from going on with technical careers because they have these terrible experiences in lab where they don't understand what's going on. Everything's kind of half broken and they end up having to follow recipes to get things to work without really feeling the freedom to explore,” he said. “With Moku:Go, they can take a bag of electronics home with them, including Moku:Go, and then they can do all the labs remotely at their own pace.”

The most advanced of the portfolio, Moku:Pro, has been specially designed for sensitive research and has four analog input and output channels.

Speaking of the quick start-up functionality of these three products, Shaddock added, “The most expensive part of any test system is often the time it takes for an engineer to work with that system: setting it up, maintaining it, and programming it. Everything we do is about leveraging that time, so that we can get the most value out of it.”

From University Labs to Space Instruments

Liquid Instruments aims to offset a revolution in the current T&M instrument market.

While the Moku product series is useful for students both inside and outside the lab, this tool is also precise enough to be used among NASA engineers, according to Shaddock. “The first sales were used for gravitational weight detection, which is the most sensitive measurement device that has ever been made,” he remarked. “We started off selling to people in cutting-edge photonics research. That could be people developing quantum computing, LiDAR systems, and spectroscopy for new types of medical diagnostics.”

Placing an FPGA at the heart of the system is a forward-thinking approach to integrate multiple instruments into a single device—especially in an age where at-home testing has become more commonplace.

“Xilinx and Intel spend billions of dollars making FPGAs faster every year, and we kind of swoop along in their slipstream with their latest chips,” Shaddock said. “We've hitched our way into Moore's law in some ways with these FPGAs. Now, our system has many advantages in terms of cost, performance, and functionality.”



All images used courtesy of Liquid Instruments.