The aim of this research is the development of low-cost and small size Single Package Radio System (SPR). Advances in integration technology and device performance paved the way for higher level of System integration On Chip (SOC) or In Package (SIP). Complete front end radio for cellular systems includes several blocks, RFIC transceiver, Power Amplifier (PA), and Front End Module (FEM) blocks in addition to control circuitry and matching components. In present state of the art systems, Si CMOS, Si or SiGe BiCMOS, GaAs HBT, and GaAs PHEMT are used for IC implementation, while ceramic, LTCC and laminate substrates are employed for passive components and circuits plus packaging, in addition to Surface Acoustic Wave (SAW) technology necessary for filtering. So hybrid solution that blends SOC and SIP might be the only viable approach, at the present time, to achieve the desired level of integration for complete front end radio in a Single Package Radio (SPR). This SPR solution is capable of mixing and matching the different technologies based on lowest cost, smallest size, and lowest power consumption assuming the system specification is satisfied by default.
A novel inductor resonators filter structure is designed. The design can achieve compact filter design even on low cost relatively low dielectric constant material. The design is based on the self-resonance frequency of the spiral inductors and electromagnetic coupling effects between resonators. The center frequency and bandwidth of the arbitrary shape spiral inductor resonator filters can be optimized using proper multilayer configurations and effective electromagnetic coupling. The compactness of newly developed bandpass filter makes the design of bandpass filters attractive for further development and applications in System-In-a-Package.
The new multilayer embedded Front End Module (FEM) for GSM/DCS dualband in laminate substrate was recently demonstrated in our group. The newly developed diplexer with embedded spiral inductor consists of two embedded inductors and five SMT capacitors. The insertion losses are about 0.243 dB for GSM band and 0.382 dB for DCS band. The rejection signals of the other channels signal are greater than 17 dB for both bands. All of these technologies should be integrated on chip carrier, laminate or LTCC substrate. Laminate substrate not only provides the lowest possible cost solution, but also presents a natural migration for the system implementation from laminate based Printed Circuit Board (PCB) to laminate package substrate.
The superdiplexer we design allow to remove three discrete components from the radio module (2 filters and one diplexer) while integrate all these functions in the printed circuit board.