Low distortion and low noise oscillator-mixer IC for CATV converters

A low-distortion and low-noise oscillator-mixer IC sufficient for practical use in CATV (cable television) converters has been successfully developed. The IC consists of a double-balanced mixer (DBM), a voltage-controlled oscillator (VCO), and balance-unbalance converters (baluns). To obtain high IM/sub 2/ (second-order intermodulation distortion) and low noise figure, special care for designing the IC was taken to suppress the unbalance in the DBM and baluns and to obtain high g/sub m/ in constituent FETs. The converter using the presented IC has superior characteristics to those of conventional converters by 15-20 dB in IM/sub 2/, 2-3 dB in noise figure, and less than -20 dB in local isolation for the CATV band.<
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