X Band Single Gate GaAs MESFET Active Mixer Fabrication and Measurement

• Main Authors: Wen-yang Chow, 周文揚
• Other Authors: Christina F. Jou
• Format: Others
• Language: en_US
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/65650542916197500604

碩士 === 國立交通大學 === 電信研究所 === 83 === In this thesis, a X-band GaAs MESFET single-gate active mixer was desined, fabricated, and measured. This mixer which the LO and RF signals applied to the gate, and with the IF filtered from the drain. The primarily advantage of single-gate active mixer are conversion gain and low noise figure , but difficult to achieve good LO-to-RF isolation. Because time- varying transconductance is the dominant contributor to frequency conversion, it is important that maximize the fundamental LO- frequency component of the transconductance waveform. Therefore, the gate port can not have IF-frequency and unwanted mixing frequency, the drain port also can not have LO-frequency and harmonics, and provide port-to-port isolation, these problem are need to overcome. We used CAD Libra program to simulation and optimization, a high rejection low-pass filter, choke for bias network, and input matching circuit are designed, fabricated. Finally, a LO frequency is 10 GHz, RF frequency is 12 GHz, and IF frequency is 2 GHz single-gate GaAs MESFET active mixer was designed, fabricated, and measured, we had 5 dB conversion gain.