When Amazon launched its Fire TV Stick 4K in October 2018, it proved tremendously popular for three reasons. One, it delivered powerful 4K streaming with support for stellar audio (Dolby Atmos) and video specs (Dolby Vision). Two, it was a simple, compact stick. Three, it cost less than $50. The first was necessary. The second convenient. But it was the third that made all the difference.
Rewind to 2017, though, and Amazon engineers who had been tasked with creating what would become the Fire TV Stick 4K had a problem: bringing those three facets together was not possible with existing technology. What happened next was world-class engineering, innovation, and collaboration. This is a behind-the-scenes look at the unique challenges the engineering teams faced in creating the Fire TV Stick 4K, and how they used scientific research to drive fundamental innovation to overcome those challenges.
Before the Fire TV Stick 4K launched, Amazon had other 4K streaming devices on the market, including the Fire TV pendant and Fire TV Box, but at $70 some considered these too expensive. Determined to improve value to the customer, Amazon product managers wanted to create a device that would be cost effective while delivering a quality streaming solution. They concluded that the best way to keep the materials cost low enough would be to create a small, all-in-one HDMI stick.
“The size! Initially we thought we couldn’t do it at all,” recalls Deepak Pai, a senior wireless system engineer at Amazon Lab126 in Sunnyvale, California. “If you make it too big, it doesn’t fit at the back of the TV. If you make it a weird shape, it’s not a stick anymore.”
Noise is not an option
The critical issue that made this engineering task particularly challenging ties to the high data rate required to stream 4K video content over Wi-Fi. This data rate leaves virtually no room for error, and Amazon’s previous Fire TV Stick, which was not designed for 4K, experienced radio frequency interference (RFI) at 4K speeds, creating a patchy viewing experience.
It was crucial to resolve any interference or noise issues, so that we could deliver a reliable 4K viewing experience for our customers, without buffering issues.
This interference — a headache for electrical engineers the world over — is caused by the radio-frequency noise emitted by electronic circuits. The engineers quickly realized that, with 4K, noise is not an option. “It was crucial to resolve any interference or noise issues, so that we could deliver a reliable 4K viewing experience for our customers, without buffering issues,” says Jagan Rajagopalan, senior radio frequency systems engineer at Lab126, who led the engineering team.
But the imperative of keeping the new device below $50, and therefore using a stick form, created a big challenge. An HDMI stick, with its sensitive antennas for picking up Wi-Fi signals, sits very close to the TV, exacerbating the RFI challenge.
Previous generations of Amazon’s Fire TV streaming media sticks were designed for lower-resolution TVs, with a lower rate of data transfer, so this noise was filterable, says Rajagopalan. With 4K, however, it was a different proposition altogether. “Traditional signal-conditioning methods wouldn’t work because of the sheer speed of 4K. No noise-friendly antennas existed for a small form factor, so it was critical for us to look around the corner and innovate. We would have to mitigate RFI through fundamental invention.”
No noise is good noise
Addressing RFI in a stick was particularly challenging because of the closely located noise sources from the antenna. To better understand what was going on at the smallest scales, the team created both physical prototypes and a full 3D electromagnetic simulation model that included fine details of its mechanical aspects — such as the antenna, printed circuit boards (PCB) electronics, shielding, heat sink, and HDMI connector — as well as its all-important electrical properties.
For every Amazon product, engineering teams come together, but on this product, it was at a whole new level.
This led them to a multi-pronged approach. One aspect was to reorganize the integrated circuits in the printed circuit boards to reduce their noise emissions. Another aspect was to come up with a novel antenna design that was noise-friendly. “Other available streaming devices use conventional antennas, such as monopole antennas,” says Mohammed Azad, senior antenna design engineer at Lab126. “However, these are not noise-friendly and tend to degrade their performance in presence of noise.” The Amazon Lab126 team invented an antenna design that was noise-friendly. This was a science and engineering breakthrough because conventional antennas in small devices did not meet its design goals.
Getting this far required extensive academic research, particularly because the stick would measure just 99mm by 30mm by 14mm. “We have teams that focus on the different aspects of the device: thermal, signal integrity, power integrity, and reliability. And because this device is so small, every little design change caused cascading changes for the other teams,” says Pai. “For every Amazon product, engineering teams come together, but on this product, it was at a whole new level.”
Tight-knit team
The two key problems of device noise and TV noise were, in principle, solved, but the proof would be in the pudding. The device had to work for all TVs. So the team ensured that the prototype 4K stick worked when used with more than 100 different makes and models of TV. This rigorous testing confirmed that their proof-of-concept 4K stick had met its design goal of being able to stream 4K television to any TV. And they had done it in under six months. From there, the Amazon product managers got to work turning the prototype into the customer-ready Fire TV Stick 4K.
While the Fire TV Stick 4K story is a good example of Amazon’s obsession to provide value to its customers, it is a reminder that the ability to do so relies on the innovation and collaboration of the scientists, engineers and product managers focus on delivering best-in-class products that customers love.
