An X-band transmission line based CMOS VCO with FM modulation

An X-band voltage-controlled oscillator (VCO) with frequency modulation (FM) capability is realized in a 0.18 mu m 1P6M CMOS technology. The characteristics of the VCO modulated by a 100KHz triangular waveform are presented and investigated. The passive components of the VCO are implemented by two-dimensional (2-D) complementary-conducting strip transmission lines (CCS TLs), varactors and metal-oxide-metal (MOM) capacitors for substrate coupling consideration. The measured VCO with free running phase noise of -83.2 dBc/Hz at 100KHz offset from the carrier. The compact VCO chip size is 330 x 450 mu m(2) excluding pads. Furthermore, the modulation bandwidth is up to 400MHz of the proposed VCO with direct FM modulation which could improve range resolution in a radar system.