Jacqueline Hochheiser, Corporate Communications

At Mini-Circuits, we constantly strive to exceed expectations and set new industry standards, and that ethic applies nowhere more than in our new product development. Over the last four years, the LTCC design team has been hard at work expanding the frequency range of Mini-Circuits’ low temperature co-fired ceramic (LTCC) filter line into the millimeter wave region. If you’re unfamiliar with the term, “millimeter wave” refers to frequencies from roughly 30 to 300 GHz. These bandwidths have become the focus of development for a number of emerging applications, including 5G networks, and they’re a high priority for Mini-Circuits to capture new business.

LTCC product line manager, Aaron Vaisman, set a goal four years ago to design an LTCC filter that could reach 40 GHz to expand Mini-Circuits’ offerings and refresh the LTCC portfolio. LTCC filters at such high frequencies aren’t just new for Mini-Circuits; they represent an industry-leading innovation and an answer to several longstanding technical challenges inherent to LTCC technology. Releasing these models and accomplishing their goal in four years, a relatively short timeframe for an effort of this scope, was a rigorous process encompassing all elements of product design and production, and Vaisman attributes his team’s success to their close-knit dynamic and hard work.

“I could not be prouder of my team and what they have accomplished. It’s their hard work, tenacity and disciplined thought and execution that gives us these results,” said Vaisman.

All members involved with the project played significant roles in the research, design, and commercial release of the new filters. Camilo Gomez Duarte inherited the project from a former team member to expand the LFCN-series of low pass filters with passbands reaching beyond 30 GHz. Camilo proved his adaptability and passion for his work as design engineer by finishing the project and achieving the desired results.

Camilo was also the lead design engineer working on the new BFCQ-series of band pass filters reaching up to 40 GHz and realizing the team’s ultimate goal, while mentoring new design engineers on the LTCC team and coaching them on the design process.

Alongside Camilo, aiding in the efforts were project managers Atharva Powale and William Yu, who were instrumental in guiding the LTCC filters successfully from inception to market release. Atharva was responsible for interfacing with the Quality Assurance team to finalize a qualification plan. William worked particularly closely with Camilo creating a detailed schedule of check points the filter would have to pass, as well as identifying roadblocks in the schedule to prevent delays before they happened. William also served as liaison between Mini-Circuits in Brooklyn and the Mini-Circuits team in India, who were responsible for assisting in designing and documenting several of the low pass filters.

To help keep the effort moving smoothly, design engineer Shaokang Li provided William and the LTCC design team with understanding of Mini-Circuits’ internal processes and the best ways to maneuver within the company, as well as the methodology behind the release to market.

With so many moving parts and different departments involved, Aaron was pleased with the overall outcome and the smooth progression of the products as they transitioned from theory, to fabricated design, and finally to qualification for market. Global VP of quality and reliability Ketan Patel’s team was especially helpful in determining the most suitable stress tests to subject the filters to, as well as lending perspective on quality and manufacturability. Benham Tabrizi also assisted in proposing and reviewing the stress tests and validations of the filters to assure that their performance was in alignment with the intended applications.

A well-oiled team can power through all the challenges and road blocks encountered along the journey, and there were certainly plenty in designing LTCC filters with millimeter wave capabilities. One of the most prevalent issues that arose in the beginning of the design process was determining a suitable material to use as a conductive paste. Due to the filters’ smaller size as a result of new requirements for miniaturized case styles, traditional conductive pastes were melting off during the soldering process.

 In addition to fabricating a new, stickier paste, the team was also tasked with fitting the necessary circuitry into a smaller package. During the simulation phase, the design engineers worked tirelessly to figure out clever ways of distributing the internal 3D circuit topologies without sacrificing performance and quality.

“We had to get very creative in the way we designed the internal topologies to accommodate different frequencies,” said Camilo. “You always need to be mindful of the different aspects of designing a filter: the math theory, the design process in simulation, and keeping in mind real-world parameters and limitations to ensure manufacturability.”

Despite these challenges, the team designed a filter superior to its competition in many ways, adding to Mini-Circuits’ extensive LTCC filter portfolio. To date, Mini-Circuits is the largest supplier of millimeter wave LTCC filters in the world, providing higher stopband rejection, and wider range of application bands than our competitors.

The team’s aspirations don’t end here, and they continue to push the limits of LTCC technology and to provide even greater selection for our customers. Aaron and his design engineers hope to increase frequencies up to 67 GHz in the future, and are close to releasing filters with unprecedented stopband rejection performance up to 80 dB, unheard-of in LTCC technology until now.

For Camilo, seeing the final products performing in real-life just as they did in simulation gives him a sense of accomplishment. “We do a lot of simulation. I find that process to be interesting and fun,” he said. “It’s cool to see all that work pay off in the real world.”

Congratulations to the entire LTCC team and to the individuals and departments that played a role in releasing Mini-Circuits’ newest LTCC products to market.