||The ever-increasing demand for global mobility and multimedia services drives wireless communication systems towards a multi-mode, multi-band and multi-standard trend. Such demand calls for innovative integrated designs that can work across multiple standards with maximum hardware sharing and minimum power consumption to enable low cost and long talk time. In this thesis, novel reconfigurable Voltage-controlled Oscillator (VCO) and Quadrature Voltage-controlled Oscillator (Q-VCO) topologies and divide-by-3 Injection-locked Frequency Divider (ILFD) topology are presented. The VCO and Q-VCO realize stable dual-band operation by introducing a notch-peak cancellation concept in transformer-based LC tanks. The ILFD realizes the division ratio of 3 and quadrature outputs with low power consumption through transformer feedback. Three different prototypes are demonstrated in CMOS processes with 1V voltage supply. The first design, a VCO implemented in a 0.13-μm CMOS process, achieves dual-band operation from 5.19GHz to 6.67GHz and from 15.99GHz to 19.06GHz and measures phase noise better than -132.2dBc/Hz and -125.5dBc/Hz at 10MHz offset, while drawing only 1.5mA and 6mA, respectively. The VCO only occupies an active chip area of 0.16mm2. The second design, a Q-VCO fabricated in a 0.18-μm CMOS process, measures a dual-band operation from 3.27GHz to 5.02GHz and from 9.48GHz to 11.36GHz. At 4.2GHz and 10GHz, the Q-VCO measures phase noise at 1MHz offset of -116.3dBc/Hz and -112dBc/Hz, and sideband rejection ratios (SBR) of 49dB and 47dB while drawing 6mA and 10mA, respectively. The Q-VCO occupies an active area of 0.88 mm2. The third design, a transformer-feedback divide-by-3 ILFD fabricated in a 0.13-μm CMOS process, measures an input frequency range from 22.7GHz to 25.1GHz with 2nd and 3rd harmonic tones of -45 dBc and -40 dBc, respectively. With quadrature outputs, the divider achieves a sideband rejection ratio of 40 dB while consuming only 1.7mW and occupying an active area of 0.23mm2.