Welcome to... "Micro-Lesson 262"
The progression uses three chords from, "G Major's," harmonized scale. They are; "Cmaj7," "Bm7," and "Am7." Although these chords are used in the progressions chord changes, the progression itself does not lean in a solid manner toward any one point of harmonic resolution, (related to the key signatures major or minor tonality).
This is categorized as being, "Modal." When chords of a diatonic harmony other than the major or minor tonality cannot be distinguished as, "home," (tonal center), we have a modal progression.
Another interesting idea that occurs with these chord changes are the voicings and chord locations on the fingerboard. In measure one the "Cmaj7" chord occurs at the 3rd position. However, into the second measure we apply a "Cmaj7" into the 8th position. This is an excellent idea to experiment with when composing progressions on the guitar. We can point into different fret-board locations with our voicings to generate new and unique sounds.
At the mid-point of this riff there is a fast-paced turnaround lick played from the second measures 3rd beat. It's a quick line, so be sure to memorize it prior to pouring on the speed.
The progression wraps-up by playing chord shots off of our riff's three chord types, all rooted from off of the 6th string. Enjoy!
Micro Lesson 262: "Key of G" Pop-Jazz Modal Riff