We report on low noise performance of a 10 GHz actively mode-locked laser. The laser is a fiberized ring laser using a commercially available semiconductor optical amplifier (SOA) as the gain medium. The noise properties as a function of cavity length and optical spectrum are investigated. It is found that supermode noise is reduced when the cavity length is increased past a certain threshold. Best performance is achieved with a 20 meter cavity whose pulses are down chirped. No active feedback control is utilized to reduce the noise, yet the integrated jitter is only 29 fs (10Hz-100MHz)
