This generation of flagship devices from Samsung in the Galaxy S21 line is quite different from that of previous years, as Samsung chose to create a line of devices much more uneven between the Galaxy S21, S21 + “standard” and the larger ones, more Galaxy Feature-packed Ultra S21.
In addition to the cameras and the general format, the only area in which the Galaxy S21 Ultra differs significantly from its siblings is the screen. This is not only due to the cheaper brothers who choose to downgrade to FHD resolution panels, but also because the S21 Ultra generationally employs an unprecedented OLED screen that exceeds the limits in terms of technology.
120 Hz QHD finally, but still limited VRR
One of the biggest changes in the capabilities of the S21 Ultra display is the ability to finally run the display in its native resolution of 1440 x 3200 at 120 Hz – an option that was previously not possible on S20 or Note20 series devices.
Samsung’s way of enabling this is relatively straightforward and in line with what we saw on the OnePlus 8 Pro last year: the MIPI interface clock has been increased from 1157 MHz to 1462 MHz. It is still a unique 4-track interface in terms of width, but as with the 8 Pro, the increased frequency allows enough bandwidth to allow 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 seamless exchange between refresh rates.
We covered this new VRR (variable refresh rate) extensively in our Note20 Ultra screen analysis and how it works transparently for the hardware, and how the LFD (low frequency drive) is capable of achieving great efficiency benefits. power when in the “Adaptive” screen refresh rate mode.
In this respect, the Galaxy S21 Ultra behaves in the same way as the Note20 Ultra. It should be noted that this also includes the behavior of the VRR mechanism not working in low ambient brightness situations, with power consumption varying depending on what the phone’s ambient light sensor is picking up. This means that, in situations of greater luminosity, in which the ambient light sensor detects luminance beyond 40 lux, the VRR and LFD are apparently operating as planned.
The Galaxy S21 Ultra now allows QHD at 120 Hz, which means we have 2 additional operating modes for the screen compared to how the Note20 Ultra did things:
At the 60 Hz QHD resolution, the basic power consumption of the S21 Ultra (a variant of the Exynos 2100 in this context) uses 469 to 481mW of power on a completely black screen in terms of the device’s total power. Similar to the Note20 Ultra, we are seeing that there is still some type of VRR / LFD operating when in 60Hz mode, as the screen will consume less energy when in lighter environmental situations, although the delta here is smaller than what we saw in Note20 Ultra .
At 120Hz FHD, the same operating modes as the Note20 Ultra, the S21 Ultra here seems to consume 130mW more for some reason, ending at 558mW over the Note8 Ultra’s 428mW. I’m not sure why we’re seeing this bigger difference between devices, but we’re talking about different DDICs and different panels together with different SoCs here.
The S21 Ultra here compares very well with the Snapdragon S20 Ultra, using up to about 200mW less power, although the difference for the Exynos S20 Ultra is not that big at just about 45mW.
Unfortunately, the big problem with Samsung’s VRR / LFD mechanism is the same as the Note20 Ultra, since when you’re in ambient light conditions below 40lux, the energy saving mechanisms no longer work and the phone will consume a lot of energy, similar to what we saw on the Snapdragon S20 Ultra last year.
If you are using the phone in the dark or even in low light conditions, the variable refresh rate does not work at all, and the 120 Hz mode has a huge cost of 300 mW in baseline energy. Since the display panel generally uses less power in such conditions, because I am assuming it works at lower brightness levels, this baseline energy impact is a very large% of the device’s total power consumption.
I wasn’t a big fan of that aspect of the Note20 Ultra and the previous generation’s 120 Hz implementations – I would like Samsung, instead of disabling VRR / LFD in low light conditions, to simply switch to 60 Hz mode, as it would be a much more energy efficient alternative. Of course, the best solution would be to simply get rid of this limitation of ambient brightness and allow 120 Hz and VRR in all conditions – it is still not exactly clear the technical reason why Samsung is employing this limitation in the first place, like me ‘ I’m not seeing any difference in the quality of the screen by cheating the phone’s ambient brightness sensor and switching between VRR / LFD on and off.
A new generation of OLED emitter – big leaps
So while QHD 120Hz and VRR / LFD are interesting, they are not exactly the latest technologies, although Samsung finally brings them to the Galaxy S series (well, Ultra, at least).
The most interesting part of the Galaxy S21 Ultra screen is the fact that it is the first to use a new generation OLED emitter. Over the years, there have been noticeable leaps in the energy efficiency of OLEDs, and most of them have been associated with the launch of new generation emitters that have improved their predecessors. Samsung doesn’t say much about the technical descriptions of these emitters or their generational nomenclature, but the S21 Ultra is one of those new generations.
To measure the difference between screen generations, we simply measure the power consumption of the different devices at various levels of screen brightness, comparing the new Galaxy S21 Ultra with the previous generation S20 Ultra and also adding the Note20 Ultra as extra data -Score:
Right away, we can see that there is a big difference in the luminance capacity of the screen, as well as in the energy consumption for the new S21 Ultra. The various devices start at almost the same starting point of basic power consumption on a completely black screen: 481mW for the S21 Ultra, 510mW for the S20 Ultra and 476mW for the Note20 Ultra. We are measuring things in 60 Hz mode, as we are only focused on the luminance power of the monitors.
Compared to the S20 Ultra, with 200 and 400 nits, the S21 Ultra is about 22% more efficient when displaying white in full screen. In fact, it’s a huge number, since we are measuring the total power of the device, not just the screen.
If we are normalizing the power curves for baseline power, the S21 Ultra is actually even more efficient – 26% to 31%, depending on the level of brightness.
In fact, while the screen of the new S21 Ultra is the brightest Samsung has ever delivered, reaching full-screen white levels of up to 942 nits, it uses less energy than the S20 Ultra’s 778 nits peak brightness. Peak power is also 20% lower than the Note20 Ultra, although it is also 31 nits brighter.
It is interesting to see the power curves of the S20 Ultra vs. Note20 Ultra here – the two correspond to approximately 150 nits, after which the Note20 Ultra takes the lead, however the advantage here seems to be more fixed in terms of absolute mW, as the power curves continue to run parallel to each other. others – efficiency gains are likely to come from the Note20 Ultra’s new backplane technology. The power curve of the S21 Ultra, however, is clearly more divergent with increasing brightness levels, which is a sign of improved luminance efficiency as opposed to the efficiency of the control panel, which is exactly what we would expect given new emitter technology.
Instead of demonstrating power in an unreal full-screen white, let’s take something with a more realistic medium image level, like the AnandTech homepage:
S21 Ultra and S20 Ultra
The scenario here is the S21 Ultra and the S20 Ultra side by side, set to 120 Hz FHD, calibrated to 300 nits of brightness and under brighter ambient light conditions to trigger the S21 Ultra’s VRR / LFD mechanisms.
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