[caption id="attachment_28467" align="aligncenter" width="659"] Links to source at: nptel.ac.in[/caption] Garmin changes GPS chips - why? And what does this mean going forward? When I reviewed the Fenix 8 earlier this year, I noted that a new GNSS chipset could be included based on completely renumbered GPS firmware now in use. The upgrade has now been confirmed by a very generous Fenix 8 owner tearing their watch to bits to look at the components (thanks to Ferhad Fidan, f.tipi - links in the teardown) So what's Happened? Several years earlier, Garmin switched GNSS (GPS) suppliers from MediaTek to Sony, as evidenced by the MediaTek MT3333 in the Garmin Forerunner 935 and the Sony CXD5603GF in the Fenix 6 Pro and Forerunner 245. Garmin didn't integrate the Sony chips as tightly as its competitors, who often got better accuracy with the same chip model. I generally considered the accuracy of this whole generation as unacceptable and said so numerous times in many reviews. 2022-23 saw more noticeable improvements in the GPS accuracy of Garmin devices as it started to refine its integration of the next generation of GNSS chipsets from Airoha (MediaTek) - for example, with the Airoha AG3335MN on the Fenix 7 (2022). Garmin never explicitly states the exact model of the chipset used, and Airoha has a few chip models. Performance varied by model, how Garmin powered it, and how the antenna was integrated into the design. Eventually, Garmin nailed down the performance, and I started to use the word 'good' in accuracy tests. Coros also used the same Airoha chipset and performed similarly or slightly better than Garmin. As we now know, from late 2024, we saw Garmin change supplier to Synaptics in the Fenix 8 and probably also in the Instinct 3 and Vivoactive 6. Fenix 8 delivered the best GNSS accuracy I've ever seen from Garmin, and the performance is right up there with the best of the competition - all the big names can now get good GPS accuracy. Why has Performance Improved? The Synaptic chipset represents 3rd or 4th generation technology, depending on how you want to classify it. The latest dual-frequency (L1+L5) GNSS chipsets have become smaller and more energy efficient. More than that, there is improved shielding from interference, better filtering away of LTE signals, improved wake-up times, and improved algorithms to reject dual-frequency signal mismatches. Synaptic might describe the improvements in more technical terms along these lines: Smaller Process Node – moved from ~55nm or 40nm to 28nm or lower, reducing dynamic and leakage power. Integrated RF Front-End – tighter SiP (System-in-Package) integration with RF filters, LNAs, and oscillator components, cutting PCB size and BOM (bill of materials cost). Enhanced DSP and Baseband Logic – redesigned low-power signal processing pipeline optimised for IoT duty cycles (e.g. burst reception, assisted GNSS). Newer Power Management Architecture – more advanced power gating and sleep states, allowing near-instant wake with minimal drain. Advanced Packaging – Flip-chip BGA or wafer-level packaging minimises parasitics and enhances heat/power efficiency. Refined RF Isolation and Noise Immunity – better RF shielding techniques for wearables, improving signal acquisition under noisy conditions. As consumers, when we look at the changes between generations over the years, we perhaps only notice the faster signal acquisition and seemingly more responsive and increasingly accurate GPS readings. It's been a long haul to get here - we started with GPS-only chips (GPS is a specific American satellite system, a term we use generically). We saw GLONASS (Russia) satellite constellations added, and then Galileo (European Union). Merged in with these improvements were the additions of one more reception frequency and more satellites from additional constellations for India (NavIC), Japan (QZSS) and China (BeiDou) The latest generation has optimised the entire chip architecture specifically for wearables One of the other key changes has been for the newer process nodes. You will see the chips in the iPhone 16 boasting a 3nm 'process node'. The smallest number is best, simplistically meaning that more 'wires' can be packed closer together, but the sizes are so small that quantum effects will soon impact performance if they get smaller (below 2nm). Even so, the Synaptics chipset works at 7nm - a massive improvement from the earliest GNSS chips and a notable improvement from the Airoha chips. But with more improvements possible. Here’s a detailed comparison table highlighting why Garmin might have considered the move from the Airoha AG3335M GNSS chipset to the Synaptics SYN4778: Feature Airoha AG3335M Synaptics SYN4778 Why This Matters for Garmin GNSS Bands Dual-band (L1 + L5) GNSS Dual-band (L1 + L5) GNSS Both support high-accuracy positioning, but performance differs by chipset. Supported Systems GPS, GLONASS, Galileo, BeiDou, QZSS, NavIC GPS, GLONASS, Galileo, BeiDou, NavIC, QZSS Comparable coverage Chip Size / Package ~6 mm x 6 mm (QFN-40) 4.0 mm x 4.0 mm (QFN-24) SYN4778 is ~30% smaller, freeing up board space for battery/sensors. Power Consumption ~28 mW (typical) ~5–6 mW (L1 + L5 mode) Up to 80% lower power in SYN4778 improves battery life. Fabrication Process Older node (~28nm) 7nm process Smaller node = better power efficiency and integration options. Cold Start TTFF (Time To Fix) ~26–30 seconds ~15–20 seconds Faster fix = better user experience in daily outdoor use. Integration & PMU Requires external LDOs/regulators Integrated Power Management Unit (PMU) Reduces PCB complexity and component count. Accuracy (Urban Canyon) ~1.5–2.0 meters typical ~<1.5 meters in urban conditions More consistent tracking accuracy in challenging GPS environments. Target Applications Automotive, mobile, wearables Wearables, IoT, asset tracking SYN4778 is tuned for wearables, not general-purpose like AG3335M. Vendor Focus Airoha (a subsidiary of MediaTek, mostly Asia-focused) Synaptics (US-based, broader wearable + IoT partnerships) Synaptics may offer better long-term support for Western OEMs like Garmin. Availability Widely available in mass production Sampling as of early 2023 AG3335M is mature; SYN4778 is 'cutting-edge'. Other Implications Technically, this is a good move to make a better product. There is another angle. MediaTek and Synaptics chips are made in Taiwan, and Sony chips in Japan. Synaptics is also considering manufacturing 10% of its chips in India, diversifying some geographic risk away from East Asia for a key component of GPS watches. The Future It is reasonable to expect GNSS chips to improve further. They will get smaller, have lower nm processes, energy consumption and even smaller sizes. Regarding how that translates into the accuracy we see on wearables, I do not expect much improvement from today's accuracy levels. I'm still unconvinced that dual-frequency signals are correctly processed in technical environments, so let's hope that can be improved. Other than that, the improvements will be under the hood. We will undoubtedly see ever more energy-efficient wearables, with GNSS chipsets contributing to better battery life. You can imagine that all other components inside our wearables are improving similarly - smaller, more energy efficient, consolidating functions of different elements in one place. As new watch models emerge, these improvements will likely boost battery lives by 10% here or 15% there. The upcoming STEP change on battery performance may come to us within months as microLED display technology on Fenix 8 microLED allows new ways to control energy consumption pixel-by-pixel. [caption id="attachment_92750" align="aligncenter" width="472"] Fenix 8 MicroLED[/caption]
