A TX VCO for WCDMA/EDGE in 90 nm RF CMOS

In English A VCO is implemented in an RF 90 nm CMOS process and covers the frequency range 2.55-4.08 GHz. Drawing 19 mA from 1.2 V, the phase noise at 20 MHz frequency offset from a 3.7 GHz carrier is -156 dBc/Hz, meeting the phase noise requirement for GSM/EDGE and SAW-less WCDMA transmitter after frequency division by 2 or by 4. A second version of the VCO covers an additional 4.90-5.75 GHz range, at the expense of a higher phase noise in the added band. In this way, all currently operational WCDMA/EDGE bands can be synthesized by a single VCO working at the double or quadruple of the desired band. A technique for shortening the transient response of the VCO during frequency tuning is also presented.