Design of a Ka-band upconverter for satellite communication

This paper presents an upconverter which can be used in a Ka-band satellite transmitter. It can be a part of satellite interactive terminal for digital video broadcasting - return channel via satellite (DVB-RCS) or can be used in a point-to-point backhaul microwave link for mobile telephony. Using complex signals, polyphase filters are analysed so that they can be used as quadrature generators and as complex filters. The upconverter translates a wideband IF signal between 0.95-1.45 GHz to a 29.5-30.0 GHz RF signal using a 14.275 GHz LO along with a frequency doubler. The upconverter makes use of a double-quadrature topology to do single side-band conversion and hence large image rejection can be achieved. By doing so, the expensive off-chip filter can be left out. The upconverter is designed in a 0.25 μm BiCMOS technology and achieves a power conversion gain of 6.8 dB, IIP3 of 17.85 dBm and image rejection of 60 dB over the RF image bandwidth. The performance has been verified using SpectreRF simulations. Mismatch is kept within limits and is supported by Monte-Carlo simulation.