This paper presents a 0.18 μm complementary metal-oxide-semiconductor (CMOS) technology high premature edge breakdown, extended spectrum and low dark count rate circular single-photon avalanche diode (SPAD) which together form a novel wide spectrum fluorescence correlation spectroscopy (FCS) detector. The circular device consists of a p+/deep n-well junction, a p-well guard-ring, and a poly guard-ring. Simulations on a Silvaco TCAD 3D device also show that the 10 μm-diameter circular p+/deep n-well SPAD device has high premature edge breakdown characteristics. Moreover，compared to the SPAD p+/n-well junction, the p+/deep n-well junction has a longer wavelength response and spectral expansion. The device achieves wide spectral sensitivity enabling greater than 40% photon detection probability from 490 to 775 nm wavelength at 0.5 V excess bias. The circular p+/deep n-well SPAD has fine avalanche breakdown is 15.14 V and a low dark count rate of 638 Hz at 25℃.