Research On Key Chip Of Microwave Transmitter Front-end

As the third generation microwave circuit, a monolithic microwave integrated circuit uses a series of semiconductor technique to fabricate active and passive components which are connected to form functional circuit on the semiconductor substrate. In this way, the size of circuit can be controled in chip level, the volume and weight of circuits are greatly reduced, and the parasitic factors are small, so it is widely used in military and civil field.Based on the process of 0.15μm GaAs pHEMT to design a Ku band medium-power amplifier and a 3~9 GHz double balanced mixer, the main research content is as follows:(1)A 12~17GHz broadband medium-power amplifier is designed, the amplifier chip has two stages, two stages are biased at the same voltage, and the amplifier works at class-A operation. The chip size is 1.5mm×0.6mm. The simulation results show the amplifier has 18 dB typical small signal gain with typical output power is more than21 dBm over 12~17GHz, typical input and output return loss are better than 12 dB and PAE is better than 23%.(2)A 3~9GHz broadband double-balanced mixer is designed, the mixer employs spiral balun for equal division and reversed-phase of signal which are loading on the diodes. The total sizes of the balun is reduced greatly by lump capacitance, the chip size is 1.4mm×1.1mm. The test results show the maximum conversion loss is 8.6dB over the working frequency ranges of 3~9GHz and output IF bandwidth ranges of DC~3GHz.The isolation of RF to IF is more than 15 dB, the typical isolation of LO to IF and LO to RF are more than 25 dB and 35 dB, respectively. The maximum conversion loss of upconverter is 8.5dB.