A broadband upconverter unit for a cable-modem double-conversion receiver

A broadband upconverter unit for double-conversion receivers used in cable modems is presented in this paper. The unit includes a variable-gain low-noise amplifier, a double-balanced mixer, a three-stage VCO bank for LO generation and a divide-by-two circuit for driving an external PLL. The unit upconverts a 6- or 8-MHz channel from 47-862 MHz input band to around 1575 MHz intermediate frequency. In experimental testing the unit measures over 20 dB gain with 8-dB noise figure and 15-dB gain tuning. The unit is implemented in a 0.9-/spl mu/m SiGe bipolar process.