A Compact Wideband Front-End Using a Single-Inductor Dual-Band VCO in 90 nm Digital CMOS

As CMOS scales down and grows more expensive, area-aware RF front-end design becomes appropriate. A wideband front-end is presented that uses an inductorless LNA and downconversion section up to 6 GHz. Frequency synthesis is realized using a single-inductor dual-band 3.5 and -10 GHz VCO. In-depth analysis describes the operation of the 4-port oscillator, and compares phase noise to that of a classical VCO. The front-end is realized in 90 nm digital CMOS. The LNA achieves a noise figure of 2.7 dB with an average IIP₃ of -2 dBm. The dual-band VCO achieves a phase noise of -122 dBc/Hz and -128 dBc/Hz at 3.9 GHz and 10 GHz, respectively, at 2.5 MHz offset. Both circuits are embedded in a wideband direct-conversion front-end consuming less than 60 mW from a 1.2 V supply.