TABLE OF CONTENTS SiP is no longer just a simple transistor package or PA module [1]. There is more functionality within the package. The SiP designer must account for system concerns that in prior designs were addressed by the OEM. The OEM dealt with these system issues on the motherboard level. The SiP designer must solve the OEM system problems in the smaller space of the package.
In addition to packaging coming full circle back to MLF/QFN, as discussed in Chapter 1, transceiver architectures have also come full circle. The superheterodyne technique replaced the direct conversion technique as wireless transceivers moved away from AM radio. This eased the filtering burden in the transceivers for FM wireless systems. The superheterodyne architectures were replaced by offset PLL architectures for GMSK modulation in GSM cellular phones. Superheterodyne transceiver architectures are quickly being replaced by direct conversion and near-direct conversion, low IF architectures for other digital modulation schemes. The direct conversion architecture allows the complete transceiver to be implemented in a single module because of the component count reduction [2]. However, direct conversion receivers enhance layout issues for small proximity packages.
Direct conversion is appealing because of its simplification of the receiver architecture [3]. However, it suffers from three major concerns: DC offsets, amplitude imbalance, and LO issues [4]. The LO can leak out the antenna port through mixer leakage and interconnect traces. This will interfere with any receivers in proximity, since the LO is at the same frequency as the transmit...
