This generation of Samsung flagship devices in the Galaxy S21 line-up is very different from the previous years as Samsung has opted to create a much more uneven device line-up between the ‘standard’ Galaxy S21, S21 + and the bigger, more feature-packed Galaxy S21 Ultra.
Aside from the cameras and general form factor, the one area where the Galaxy S21 Ultra differs significantly from its siblings is the display. This is not only because the cheaper siblings choose to downgrade to FHD resolution panels, but also because the S21 Ultra uses a brand new, unique OLED display for generations that pushes the boundaries of technology.
QHD at 120Hz, finally, but still limited VRR
One of the bigger changes in the capabilities of the S21 Ultra display is the ability to finally make the display work at its native resolution of 1440 x 3200 at 120 Hz – an option not previously available on the S20 devices. or Note20 series.
Samsung’s way of making this possible is relatively straightforward and is consistent with what we saw in the OnePlus 8 Pro last year: the MIPI interface clock has been increased from 1157 MHz to 1462 MHz. It’s still a single 4-lane interface in width, but as with the 8 Pro, the increased frequency provides enough bandwidth to now allow for the high refresh rate at high resolution.
The S21 Ultra’s panel, like the Note20 Ultra, uses a new hybrid oxide and polycrystalline backplane technology roughly equivalent to LTPO display technologies, and allows for low refresh rates and seamless switching between refresh rates .
We have discussed this new VRR (variable refresh rate) in depth in our screen analysis of the Note20 Ultra and how it works transparently to the hardware, and how the LFD (low frequency drive) is able to achieve major energy efficiency benefits in the “Adaptive” screen refresh rate mode.
In this regard, the Galaxy S21 Ultra behaves the same as the Note20 Ultra. It should be noted that this also includes the behavior of the VRR mechanism which is not functional in low ambient brightness situations where power consumption varies depending on what the phone’s ambient light sensor picks up. This means that in brighter situations, when the ambient light sensor detects luminance greater than 40 lux, the VRR and LFD will seemingly work as intended.
The Galaxy S21 Ultra now allows QHD at 120Hz, which means we have 2 additional display operating modes compared to how the Note20 Ultra did things:
At 60Hz QHD resolution, the base power consumption of the S21 Ultra (an Exynos 2100 variant in this context) consumes 469 to 481mW of power on a completely black screen in terms of total device power. As with the Note20 Ultra, we see that there is still some sort of VRR / LFD working in 60Hz mode as the display consumes less power in lighter environmental situations, although the delta here is less than what we saw on the Note20 Ultra.
At 120Hz FHD, the same operating modes possible on the Note20 Ultra, the S21 Ultra seems to consume 130mW more here for some reason, coming in at 558mW versus the Note20 Ultra’s 428mW. I’m not sure why we’re seeing this bigger difference between the devices, but we’re talking about different DDICs and different panels, along with different SoCs.
The S21 Ultra compares very well here with the Snapdragon S20 Ultra, which consumes up to about 200 mW less power, although the difference with the Exynos S20 Ultra at only about 45 mW is not that great.
Unfortunately, the big catch on Samsung’s VRR / LFD mechanism is the same as on the Note20 Ultra, because when you are in ambient light below 40lux, the power saving mechanisms stop working and the phone will consume a lot of power. , similar to what we saw on the Snapdragon S20 Ultra last year.
If you’re using your phone in dark or even dark conditions, the variable refresh rate won’t work at all, and the 120Hz mode takes a massive 300mW of base power. As the display generally consumes less power in such conditions, as I assume it will run at lower brightness levels, this basic power consumption impact is a very large% of the device’s total power consumption.
I wasn’t a big fan of this aspect of the Note20 Ultra and the previous generation’s 120Hz implementations – I wish Samsung would just switch to 60Hz mode instead of shutting down the VRR / LFD in weak conditions because that would be a much more energy-efficient alternative. Of course, the best solution would be to simply get rid of this ambient brightness limitation and allow 120Hz and VRR under all circumstances – it’s still not exactly clear on the technical reason why Samsung is applying this limitation in the first place since I’ll see no difference in the screen quality at all when I cheat the phone’s ambient brightness sensor and switch between VRR / LFD on and off.
A new generation of OLED emitters – huge leaps
So while the QHD 120Hz and VRR / LFD tech are interesting, they aren’t exactly the latest technologies, although Samsung is finally bringing them to the Galaxy S series (at least the Ultra).
The most interesting part of the Galaxy S21 Ultra display is the fact that it is the first to use a new generation OLED transmitter. Over the years, there have been noticeable leaps in the energy efficiency of OLED, and most of them are linked to the introduction of new generation emitters that improved their predecessors. Samsung doesn’t really talk much about the technical descriptions of these emitters or their generation nomenclature, but the S21 Ultra is such a new generation.
To measure the difference between the screen generations, we simply measure the power consumption of the different devices at different screen brightness levels, comparing the new Galaxy S21 Ultra with the previous generation S20 Ultra and throwing in the Note20 Ultra as additional data. -point:
We can immediately see that there is a big difference in the display luminance and power consumption for the new S21 Ultra. The different devices start at roughly the same starting point for basic power consumption on a completely black screen: 481 mW for the S21 Ultra, 510 mW for the S20 Ultra, and 476 mW for the Note20 Ultra. We measure things in 60Hz mode as we only focus on the luminance power of the screens.
Compared to the S20 Ultra, the S21 Ultra with 200 and 400 nits is about 22% more efficient when rendering full white. That’s actually a huge number considering we’re measuring total device power, not just the screen.
If we normalize the power curves to base power, the S21 Ultra is even more efficient – 26% to 31%, depending on the brightness level.
While the screen on the new S21 Ultra is the brightest Samsung has ever delivered, with a white level of up to 942 nits at full screen, it consumes even less power than the S20 Ultra’s peak brightness at 778 nits. Peak power is also 20% lower than the Note20 Ultra, although it’s also 31 nits brighter.
It’s interesting to see the power curves of the S20 Ultra versus the Note20 Ultra here – the two roughly correspond to about 150 nits, after which the Note20 Ultra takes the lead, but the benefit seems to be more fixed here in terms of absolute mW as the power curves continue to run parallel to each other – the efficiency gains are likely due to the Note20 Ultra’s new backplane technology. However, the S21 Ultra’s power curve is clearly more divergent with increasing brightness levels, which is a sign of improved luminance efficiency as opposed to panel drive efficiency, which is exactly what we would expect given the new emitter technology.
Rather than demonstrate power on an unrealistically full screen, let’s take something with a more realistic average picture level, like the AnandTech homepage:
S21 Ultra and S20 Ultra
The scenario here is both the S21 Ultra and S20 Ultra side by side, set at 120Hz FHD, calibrated to 300 nits brightness, and under brighter ambient light to activate the S21 Ultra’s VRR / LFD mechanisms.
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