Conditionaly Heteroskedastic Factor Models: Identificationand Instrumental variables Estmation

A multiple aperture ultrasonic transducer having a linear array of elements, each element having a plurality of segments forming apertures of the array, and a connection assembly for interconnecting the segments and connecting the segments to circuits. The connection assembly includes an electrode layer directly adjacent to the segments, at least one insulating layer, and at least one connector layer. The electrode layer has an electrode area for each segment and one of the insulating layers has a connection opening for each segment and connection areas for pairs of segments while the connection layer has segment to segment connectors and segment pad connectors. Each element may be divided into sub-elements with connection cross-overs offset by one sub-element along the array and alternately reversed while alternate middle segments connect to alternate sides. The connection assembly may include interlayer connector layer and may be constructed onto a carrier which may be removed before attachment to a backing body, or the connection assembly may be deposited onto the array before attachment to a backing body. The connection assembly may be fabricated as a single assembly with a monolithic block of piezoelectric material and the assembly diced to a predetermined depth and across a predetermined width so that selected connections between electrode areas and to the pads remain intact. Interlayer vias are staggered and have clearance openings extending into the dicing kerf to reduce space and to insure connection after dicing.