Inertial sensor with suspension spring structure surrounding anchor

An inertial sensor comprising:

• a substrate;
• a movable element having an edge, and an opening extending through the movable element, wherein the edge is at an inner perimeter of the opening;
• and
• a suspension system residing in the opening, the suspension system retaining the movable element in spaced apart relationship above a surface of the substrate, the suspension system including:
• an anchor attached to the surface of the substrate, the anchor having first, second, third, and fourth sides, the first side being laterally spaced apart from the edge of the movable element;
• and
• a spring structure having a first attach point coupled to the first side of the anchor and a second attach point coupled to the edge of the movable element, the spring structure including beam sections serially adjoining one another, the beam sections extending from the first side of the anchor and surrounding the first, second, third, and fourth sides of the anchor to couple to the edge of the movable element, wherein the spring structure makes no more than one coil around the anchor to position the first attach point in proximity to the second attach point, and wherein the beam sections of the spring structure include:
• a first beam section having the first attach point coupled to the first side of the anchor;
• a second beam section coupled to the first beam section;
• a third beam section coupled to the second beam section and arranged substantially parallel to the first beam section, the third beam section residing adjacent to the second side of the anchor;
• a fourth beam section coupled to the third beam section and residing adjacent to the third side of the anchor;
• and
• a fifth beam section coupled to the fourth beam section and residing adjacent to the fourth side of the anchor, wherein the third beam section is characterized by a length that is greater than a discrete length of each of the first, second, fourth, and fifth beam sections, the length of the third beam section determining a spring constant of the spring structure.