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This generation of Samsung flagship devices in the Galaxy S21 lineup is quite different from that of previous years, as Samsung chose to create a much more uneven lineup of devices between the ‘standard’ Galaxy S21, S21 + and the larger , plus feature-rich Galaxy S21 Ultra.
Beyond the cameras and the general form factor, the one area where the Galaxy S21 Ultra differs significantly from its siblings is the display. This isn’t just because the cheaper siblings are choosing to upgrade to FHD resolution panels, but also because the S21 Ultra generically uses an all-new OLED display, the first of its kind, which pushes the boundaries in terms of technology.
QHD at 120Hz, finally, but VRR still limited
One of the most significant changes in the capabilities of the S21 Ultra display is the ability to finally run the display at its native resolution of 1440 x 3200 at 120 Hz – an option that was previously not possible on S20 or Note20 series devices.
The way Samsung enables this is relatively straightforward and in line with what we saw in the OnePlus 8 Pro last year: the MIPI interface clock went from 1157 MHz to 1462 MHz. It’s still a unique 4-way interface in terms of width, but like on the 8 Pro, the increased frequency allows enough bandwidth to now enable 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 that is roughly equivalent to LTPO display technologies, and allows it to enable low refresh rates and switching. transparent between refresh rates.
We’ve covered this new VRR (Variable Refresh Rate) extensively in our screen review of the Note20 Ultra and how it works seamlessly for hardware, and how the LFD (frequency converter) is able to achieve great benefits. in terms of energy efficiency when in the “Adaptive” screen refresh rate mode.
In this regard, the Galaxy S21 Ultra behaves similarly to the Note20 Ultra. It should be noted that this also includes the behavior of the VRR mechanism which is not functional in low ambient light situations, with the power consumption varying depending on what the phone’s ambient light sensor picks up. This means that in brighter situations where the ambient light sensor detects luminance above 40 lux, the VRR and LFD apparently work as expected.
The Galaxy S21 Ultra now allowing QHD at 120Hz, means we have 2 more operating modes for the display compared to how the Note20 Ultra used to:
At 60Hz QHD resolution, the base power consumption of the S21 Ultra (an Exynos 2100 variant in this context), consumes up to 469 to 481 mW of power on a completely black screen in terms of the total power of the screen. ‘apparatus. Similar to the Note20 Ultra, we see that there is still some kind of VRR / LFD running in 60Hz mode because the screen will consume less power in brighter ambient situations, although the delta here is less than what we saw on the Note20 Ultra.
At 120Hz FHD, the same operating modes as possible on the Note20 Ultra, the S21 Ultra appears to consume an additional 130mW for some reason, ending at 558mW on the Note20 Ultra’s 428mW. I’m not sure why we are seeing this greater difference between devices, but here we are talking about different DDICs and different panels as well as different SoCs.
The S21 Ultra compares very well to the Snapdragon S20 Ultra here, using up to around 200mW less power, although the difference to the Exynos S20 Ultra is not that big at only around 45mW.
Unfortunately, the big problem with Samsung’s VRR / LFD mechanism is the same as on the Note20 Ultra, because when you are in ambient light conditions below 40 lux, the power saving mechanisms no longer work and the phone will consume a large amount of energy. , similar to what we saw on the Snapdragon S20 Ultra last year.
If you use your phone in dark or even dark conditions, the variable refresh rate doesn’t work at all, and 120Hz mode costs 300mW in base power. Since the display panel in general uses less power under such conditions, because I’m assuming it operates at lower brightness levels, this base power impact is a very large% of the consumption. total electrical power of the device.
I wasn’t a big fan of this aspect of the Note20 Ultra and previous generation 120Hz implementations – I would like Samsung, instead of turning off VRR / LFD in dark conditions, just switching to 60Hz mode. , because it would be a much more energy efficient alternative. Of course, the best solution would be to simply get rid of this ambient light limitation and allow 120Hz and VRR in all conditions – the technical reason Samsung uses this limitation in the first place is still unclear, as I don’t see any difference in screen quality by fooling the phone’s ambient light sensor and switching between VRR / LFD on and off.
A New Generation of OLED Emitters – Huge Progress
So while the 120Hz QHD and VRR / LFD tech are interesting, they’re not exactly the newest techs, although Samsung is finally bringing them to the Galaxy S series (well, the Ultra at least).
The most interesting part of the Galaxy S21 Ultra’s display is the fact that it’s the first to use a next-generation OLED emitter. Over the years, there have been notable leaps in the energy efficiency of OLEDs, and most of them have been linked to the introduction of next-generation transmitters that have improved over their predecessors. Samsung doesn’t really talk about the technical descriptions of these transmitters or their generational nomenclature, but the S21 Ultra is part of this new generation.
To measure the difference between generations of displays, we simply measure the power consumption of different devices at different screen brightness levels, comparing the new Galaxy S21 Ultra to the previous generation S20 Ultra and adding the Note20 Ultra as additional data -point:
Right off the bat, we can see that there is a big difference in the display’s luminance capacity as well as the power consumption of the new S21 Ultra. The different devices start at roughly the same starting point for base power consumption on a full black screen: 481mW for the S21 Ultra, 510mW for the S20 Ultra, and 476mW for the Note20 Ultra. We measure things in 60Hz mode because we are only focusing on the luminance power of the screens.
Compared to the S20 Ultra, at 200 and 400 nits, the S21 Ultra is around 22% more efficient when displaying white in full screen. This is actually a huge number considering that we are measuring the total power of the device, not just the screen.
If we normalize the power curves to base power, the S21 Ultra is actually even more efficient – 26% to 31%, depending on the brightness level.
In fact, while the new S21 Ultra’s screen is the brightest Samsung has ever delivered, achieving full-screen white levels of up to 942 nits, it uses less power than the S20’s 778 nits peak brightness. Ultra. Peak power is also 20% lower than the Note20 Ultra, although it is also 31 nits brighter.
It’s interesting to see the S20 Ultra vs Note20 Ultra power curves here – both are roughly around 150 nits, after which the Note20 Ultra takes the lead, but the advantage here seems to be more fixed in terms of absolute mW. , as the power curves continue to run in parallel with each other – the efficiency gains are likely to come from the Note20 Ultra’s new backplane technology. The power curve of the S21 Ultra is however clearly more divergent as the brightness levels increase, which is a sign of improved luminance efficiency compared to the efficiency of the panel control, which we expected. given the new transmitter technology.
Rather than demonstrating the power of unrealistic fullscreen white, let’s take something with a more realistic mid-frame 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 to 120Hz FHD, calibrated to 300 nits brightness and brighter ambient light conditions to trigger the S21 Ultra’s VRR / LFD mechanisms. .
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