All regular models of the Sega Saturn output composite video, S-video (Sega's first console to have S-video across all models) and RGB through a 10-pin mini-DIN connector; RF is provided through an external modulator (bundled with PAL consoles).
RGB Output Notes
The Saturn differs from the Genesis/Mega Drive in that the console already has the necessary 220 uF capacitors and 75 ohm resistors inside for RGB output, meaning that a straight pass-through cable can be used if composite video or luma are used for sync. NTSC Saturn consoles have TTL composite sync (csync) available on pin 1 of the AV out, which cannot be used directly on most displays and upscalers. If the csync output is to be used, a 470 ohm series resistor must be added to attenuate the signal and a 220 uF 10V series capacitor added to remove any DC offset.
PAL Saturns do not have composite sync and instead output 9V DC on pin 1, used for aspect ratio switching on certain TVs with SCART input. RGB cables that use csync and are meant for NTSC consoles cannot be used on PAL consoles, as this will cause damage to any attached device. RGB cables for PAL Saturns must use either composite video or luma for sync instead, and these cables can be safely used on any Saturn console.
The Japan-only Navi Hi-Saturn has the same 10-pin mini-DIN connector, but does not have RGB output. It can be added back in with a simple modification.[1]
Video Encoder
Most Saturns have the Sony CXA1645M video encoder chip, which takes in the raw RGB output from VDP2 and outputs amplified RGB, S-video and composite video. Some later consoles substitute the CXA1645 with the Fujitsu MB3516 (found in NTSC consoles) or ROHM BH7236AF (found in PAL consoles), which are both pin-compatible with the 1645.