A Ka-Band LTCC integrated 22dBm MMIC power amplifier module

Abstract

This thesis reports design and fabrication of a compact Ka-band LTCC(low temperature co-fired ceramic) power amplifier module integrating 0.25$\mum$ PHEMT MMIC power amplifier. The LTCC module was designed for surface mounting structure (SMT), and composed of five layers of LTCC circuit. Gold paste was printed on top layer in order to make gold wire bonding and the via holes on top layer were filled with Ag/Pd paste for preventing void space. Matching networks composed of microstrip open stubs are implemented on each layer of the 5-layer LTCC module to compensate parasitic inductances caused by bond wires and via transitions. RF input and output feed throughs were designed using transition from microstrip through embedded CPW to embedded microstrip. Embedded meshed grounds on layer 4 and layer 1 were used for thermal spreading and reduction of warpage. Angled double wire bonding was used for low loss connection at the microwave frequency. Total size of LTCC power amplifier module is as small as 5.5mm $\times8$ 5mm $\times8$ 0.7mm, that includes a height of bonding wire. The power amplifier module reveals 22 dBm output power and 8 dB power gain between 28 GHz and 31 GHz, and which is equivalent to 1 dB loss compared to the MMIC performance. 1dB loss includes outside loss of LTCC such as TEFLON board and conductive epoxy. Especially, the power amplifier module shows maximum output power up to 24 dBm and power gain up to 9 dB at 30GHz range. The value of 1dB includes loss originated from TEFLON evaluation board and conductive epoxy for LTCC block mounting.