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Lee S.-J.,Millimeter wave novation Technology Research Center | Baek Y.-H.,Millimeter wave novation Technology Research Center | Baek T.-J.,Millimeter wave novation Technology Research Center | Han M.,Millimeter wave novation Technology Research Center | And 4 more authors.
Microelectronics Journal | Year: 2010

In this paper, a 94 GHz microwave monolithic integrated circuit (MMIC) single balanced resistive mixer affording high LO-to-RF isolation was designed without an IF balun. The single balanced resistive mixer, which does not require an external IF balun, was designed using a 0.1 μm InGaAs/InAlAs/GaAs metamorphic high electron mobility transistor (HEMT). The designed MMIC single balanced resistive mixer was fabricated using the 0.1 μm MHEMT MMIC process. From the measurement, conversion loss of the single balanced resistive mixer was 14.7 dB at an LO power of 10 dBm. The P1 dB (1 dB compression point) values of the input and output were 10 dBm and -5.3 dBm, respectively. The LO-to-RF isolation of the single balanced resistive mixer was -35.2 dB at 94.03 GHz. The single balanced resistive mixer in this work provided high LO-to-RF isolation without an IF balun. © 2010 Elsevier Ltd. All rights reserved.


Moon S.-W.,Millimeter wave novation Technology Research Center | Oh J.-H.,Millimeter wave novation Technology Research Center | Jun B.-C.,Millimeter wave novation Technology Research Center | Kim S.-D.,Millimeter wave novation Technology Research Center
Current Applied Physics | Year: 2010

This paper presents a 94 GHz monolithic down-converter with low conversion loss and high local oscillator (LO)-to-RF isolation using the 0.1 μm T-gate metamorphic high electron-mobility transistor (MHEMT) technology. The down-converter consists of a one-stage amplifier and a single-balanced mixer based on the high-directivity tandem coupler structure using the air-bridge crossovers, thereby amplifying the RF signals and maximizing the LO-to-RF isolation by using an inherent S12 isolation characteristic of the amplifier and good phase balance of the tandem coupler. The fabricated one-stage amplifier using a 30 μm × 2 MHEMT shows a small signal gain of 7 dB at 94 GHz. The single-balanced mixer comprising two 20 μm × 2 MHEMT Schottky diodes and the tandem coupler with an additional λ/4-length line exhibits the conversion loss less than 7.8 dB and the LO-to-RF isolation higher than 30 dB in a RF frequency range of 91-96 GHz. Two circuits designed both for a 50 Ω impedance system are integrated into the down-converter of a 2.6 × 2.5 mm2 chip size, and it shows a low conversion loss of ∼1 dB at 94 GHz and excellent LO-to-RF isolation above 40 dB in a frequency range of 90-100 GHz. This is the best isolation among the W-band monolithic down-converters reported to date. © 2009 Elsevier B.V. All rights reserved.

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