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研制了用于直播卫星接收机的12GHz波段GaAs双栅MESFET单片混频器。为了缩小芯片面积,把一个缓冲放大器直接与混频器的中频端口连接,而不采用中频匹配电路。混频器和缓冲放大器分开制造在两个芯片上,以便单独测量。混频器芯片尺寸为0.96×1.26mm~2,缓冲放大器芯片尺寸为0.96×0.60mm~2。混频器的双栅FET,以及缓冲放大器的单栅FET的电极间距很小。栅长和栅宽各1μm和320μm。在11.7～12.2GHz,带有缓冲放大器的混频器提供转换增益为2.9±0.4dB,单边带噪声系数12.3±0.3dB。本振(LO)频率为10.8GHz。低噪声变频器由单片前置放大器、镜象抑制滤波器,以及单片中频放大器与混频器连接构成。在同一频段,变频器提供转换增益为46.8±1.5dB,单边带噪声系数为2.8±0.2dB。
Developed 12GHz band GaAs dual-gate MESFET monolithic mixer for direct broadcast satellite receiver. In order to reduce the chip area, a buffer amplifier connected directly to the mixer IF port, without the use of IF matching circuit. The mixer and buffer amplifier are fabricated separately on two chips for individual measurement. The mixer chip size is 0.96 × 1.26mm ~ 2, the buffer amplifier chip size is 0.96 × 0.60mm ~ 2. The double gate FET of the mixer, and the single gate FET of the buffer amplifier have very small electrode spacings. The gate length and gate width are 1 μm and 320 μm respectively. At 11.7 to 12.2 GHz, a mixer with a buffer amplifier provides a conversion gain of 2.9 ± 0.4 dB and a single-sideband noise figure of 12.3 ± 0.3 dB. The LO frequency is 10.8GHz. Low-noise frequency converter consists of a single preamplifier, image rejection filter, and a single IF amplifier and mixer connected to form. In the same frequency band, the inverter provides a conversion gain of 46.8 ± 1.5dB and a single-sideband noise figure of 2.8 ± 0.2dB.