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

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 μm SiGe BiCMOS process, the synthesizer occupies a chip area of 4.8 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.