by Ray Fontaine

Canon’s APS-C and FF CIS supply chain is much simpler than Nikon’s. While Sony CIS components have been found in Canon digital compact cameras, Table 1 shows the Canon CIS design wins for five Canon FF DSLRs analyzed by Chipworks.  The Canon APS-C devices analyzed (not listed) have all been found to be fabricated by Canon.

 

Camera Model	Date Announced	Camera Format	Die Marking/ Part Number	Resolution (Mp)	Pixel Size (µm)
EOS 5D	Aug 2005	Full frame	706P	12.8	8.3
EOS 1Ds Mark III	Aug 2007	Full frame	1060	21.1	6.4
EOS 5D Mark II	Sep 2008	Full frame	1100	21.1	6.4
EOS 1D X	Oct 2011	Full frame	X030334	18.1	6.9
EOS 5D Mark III	Mar 2012	Full frame	AD0107806	22.3	6.2

Table 1: Canon FF DSLRs with Canon Fabbed CIS

 

Canon X030334 from the 1D X

The 1D X is Canon’s flagship professional FF DSLR and is a direct competitor to the Nikon D4 [1]. It too has impressive video performance, in part due to Canon’s new intra-coded frame (ALL-I) video compression option, new for the 5D Mark III and 1D X [2]. The X030334 CIS from the 1D X uses a stand-alone (unshared) pixel architecture, although the output from odd and even rows is read separately by one of two column out buses. Similar to the “FD switch” used by the Nikon D4, for the first time Canon’s X030334 uses an additional transistor (T5) that can be used to sum the FD nodes of three rows of even (or odd) pixels of the same color. Again, the row control circuitry or other design analyses have not been performed, but it is a reasonable assumption that this architecture facilitates low noise video readout.

 Shared Pixels at Poly (L) and Pixel Cross Section (R) (click to enlarge)

On the process side, the 1D X is remarkable in that Canon continues to stay with the 0.5 µm process generation it has used for every APS-C and FF device analyzed. While the use of a mature fab likely gives Canon a competitive edge via lower manufacturing costs, it may also weigh heavily in its product development. Below (Table 2)  is a survey of 10 FF sensors analyzed by Chipworks showing the correlation between CIS manufacturer, resolution/pixel size, fabrication technology generation, and stand-alone/shared pixel readout. Given the geometric constraints of 0.5 µm design rules, Canon seems content to hang around the 21 Mp resolution for recent FF sensors through the use of shared pixels. Jumping to a higher resolution generally requires more advanced design rules and pixel sharing architecture.

 

CIS Supplier	FF DSLR	Resolution (Mp)	Pixel Size (µm)	Process Generation (µm)	Pixel Architecture
Canon	EOS 5D	12.8	8.3	0.5	Stand-alone
	EOS 1Ds Mark III	21.1	6.4	0.5	Shared
	EOS 5D Mark II	21.1	6.4	0.5	Shared
	1D X	18.1	6.9	0.5	Stand-alone
	EOS 5D Mark III	22	6.2	0.5	Shared
Nikon	D3/D700	12.1	8.45	0.35	Stand-alone
	D3s	12.1	8.45	0.35	Stand-alone
	D4	16.2	7.3	0.25	Shared
Sony	α900	24.8	5.94	0.25	Shared
	Nikon D800	36.1	4.75	0.18	Shared

Table 2: Chipworks’ Analysis Results of 10 FF Cameras

 

Granted, these are not all of Canon’s FF products, so it is worth looking at the history of FF CMOS DSLR product releases. Below is the resolution trend for Canon, Nikon, Sony, and Leica FF cameras containing CIS devices announced/released since 2002. The suggested trend is towards an increasing resolution, largely due to Sony’s 24 Mp class of FF sensors and Nikon’s D800. This does correlate with Chipworks’ findings indicating Canon FF DSLRs lag in resolution, inferred from the use of a more mature fab. However, trend lines are not without their traps – the graph represents product releases only, not sales volume. Considering Sony’s comparatively lower market share, and the D800 being a new system, the upward resolution trend in relative terms is much less aggressive. An undeniable trend is the rate of FF camera product releases: over one-third of total CMOS FF camera releases have occurred in 2012.

 

 

So, back to the rumors of Canon allegedly readying a high resolution competitor to the Nikon D800 [3]. Will Canon finally move off that 0.5 µm generation? It is worth noting that September 2012 marked the 10 year anniversary of Canon’s announcement of the world’s first CMOS FF sensor, the EOS 1Ds. While Chipworks didn’t analyze that camera, every Canon FF sensor analyzed since has used the same 0.5 µm design rules. It is a credit to Canon that it has remained competitive by continuing to optimize its pixels fabricated in a relatively mature process.

Canon does have a 0.18 µm generation CIS wafer fab process, featuring a specialized Cu back end of line (BEOL) including light pipes (shown below). It is possible to speculate that Canon may be preparing to refresh its FF CIS line to supply devices for a new FF camera system. Samsung and Panasonic currently use Cu fabs to produce APS-C and micro 4/3 CIS devices. It seems that Canon is destined to do so for APS-C and perhaps ultimately FF. Part III of this series will discuss CMOSIS/STMicroelectronics’ combined effort to produce FF CIS using sub 0.18 µm design rules for the first time.

Aside from the pixel process, there are also design considerations for Canon. Of the Canon DSLRs analyzed, the imaging chip has remained analog, with Analog Devices’ analog front end (AFE) chips handling A/D conversion en route to the Digic-branded ISPs. Perhaps the column-parallel ADCs favored by others can’t be implemented using 0.5 µm design rules, but more likely Canon is satisfied with its system design and performance.  In the spirit of speculation, if Canon does migrate to a more advanced node for fabrication, could the transition coincide with a major overhaul of the CIS and system design?

Image from Canonrumors.com/Northlight Images (L), Chipworks Cross Section of Canon Cu CIS Process (R)

Part III will cover the recent announcement by CMOSIS of its partnership with STMicroelectronics to produce a FF CIS for the new Leica system, and provide speculation on the outlook for future FF camera systems.

Full Frame DSLR Cameras Part I - Nikon vs Sony 

Full Frame DSLR Cameras Part III – New Entrants and a Look Forward 

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 Chipworks Reports Mentioned in This Article

• Sony IMX094 36.3 Mp, 4.75 μm Pixel Size Full-Frame Format CMOS Image Sensor from the Nikon D800 DSLR Imager Process Review (IPR-1205-803)
• Nikon 16.2 Mp, Full-Frame Format CMOS Image Sensor with NC81366W Die Markings from a D4 DSLR Camera Imager Process Review (IPR-1205-802)
• Canon X030334 18.1 Mp, 6.9 μm Pixel Size Full-Frame CMOS Image Sensor from the Canon EOS-1D X DSLR Camera Imager Process Review (IPR-1205-805)
• Canon LC1320-C1 12.1 Mp, 1.85 µm Pixel Pitch CMOS Image Sensor from the PowerShot S100 Camera Imager Process Review (IPR-1203-901)

Chipworks is the leader in image sensor technology analysis. Download a list of reports in this sector and contact us for information about our line of Circuit, Process or Benchmarking reports. For summary comparative analysis contact us today.

 

 

References

[1] http://www.dpreview.com/news/2011/10/18/canoneos1dx

[2] http://learn.usa.canon.com/resources/articles/2012/ipp_ipb_all_i_compare.htmlp

[3] http://www.dpreview.com/news/2012/09/17/Leica-M-full-frame-24MP-CMOS-rangefinder-with-focus-peaking-live-view-and-1080p-movies