Phased array antenna systems are disclosed. An antenna system as disclosed herein can include a plurality of antenna or radiating elements formed on a common plane comprising a first surface of a circuit board. Each antenna element has one or more feeds. Integrated circuits are placed on a second surface of the circuit board. Each integrated circuit is associated with one or more of the antenna elements. Signal lines connecting an integrated circuit to a feed of an antenna element can be shielded using interlayer ground planes and interlayer conductive plugs. In addition, back surfaces of the integrated circuits can be connected to a common heatsink using a thermally conductive medium.