Is 802.11n channel bonding the only way to get link speed of 300mbps?

Is 802.11n channel bonding the only way to get link speed of 300mbps?

Is 802.11n channel bonding the only way to get link speed of 300mbps? Some
access points have two or three antennas, how does this affect MIMO and
link speeds?
Am I correct in assuming that to get link speeds of 300mbps without
channel bonding one would require three MIMO streams (3x3), and that
300mbps is possible in a 2x2 configuration with channel bonding?