A low noise and low power dissipation downconverter MMIC for DBS applications

In this work, using 0.2 /spl mu/m GaAs modulation doped FET (MODFET) technology, a high performance DBS downconverter MMIC was developed for direct broadcasting satellite (DBS) applications. Without an LNA, the downconverter MMIC showed a very low noise of 4.8 dB, which is 5 dB lower than conventional circuits. A low LO power of -10 dBm was required for normal DBS operation of the downconverter MMIC, which reduced the power consumption to 175 mW via removal of the LO amplifier on the MMIC. The LO leakage power at IF output was suppressed to a level lower than -30 dBm, which removes a bulky LO rejection filter from the board. The fabricated chip, which includes a mixer, IF amplifiers, and LO rejection filter, exhibits a small size of 0.84/spl times/0.9 mm/sup 2/.