An Integrated 0.6–4.6 GHz, 5–7 GHz, 10–14 GHz, and 20–28 GHz Frequency Synthesizer for Software-Defined Radio Applications

摘要

We present an integrated frequency synthesizer which is able to provide in-phase/quadrature phase signal over the frequency bands 0.6–4.6 GHz, 5–7 GHz, 10–14 GHz, and in-phase signal over 20–28 GHz for software-defined radio applications. An integrated voltage-controlled oscillator (VCO) with 34 tuning range and a set of high-speed dividers are used to accomplish all the frequencies. To achieve a wide tuning range while keeping a low gain and a low phase noise, the VCO employs digitally controlled sub-bands. The measured PLL phase noise is ${-}$ 108$~$dBc/Hz, ${-}$121 dBc/Hz, and ${-}$135 dBc/Hz at 1 MHz offset for 24 GHz, 4 GHz, and 700 MHz, respectively. Fabricated in a 0.25 $mu$m SiGe BiCMOS process, the synthesizer occupies a chip area of 4.8 ${hbox {mm}}^2$. The synthesizer was optimized for reconfigurable base station applications, but can also be used for cognitive radio, radar systems, satellite communication, and high-speed digital clock generation.