The DSLR-A290 has a CCD sensor type which is better than the MOS sensor type found on most recently released comparable spec digital cameras. CCD sensors produce high quality, low-noise images but consume a lot more power than CMOS sensors. CCD is the most common image sensor type used in digital cameras.
A CCD sensor type is in fact the best sensor type across all latest SLR cameras.
The worst sensor type amongst similar types of camera is MOS.