The goal of this thesis is to design and to implement a phase shifter and a power amplifier for phase-array system applications. The phase shifter is designed at K-band with continuously phase tuning and with low insertion-loss variation using standard 0.18-μm CMOS process. The power amplifier is implemented at V-band using 65-nm CMOS process with a pre-distortion linearizer. Recently, the demand for wireless communication is growing rapidly that motivates the operation frequency toward millimeter-wave frequency to provide wider bandwidth for Gigabit wireless applications. To enhance spectral efficiency, modern communication system tends to use complex modulation techniques like 64-QAM which requires a highly linear power amplifier in the transmitter. Power back-off techniques is often used to achieve the linearity requirements, but in expense of power-added efficiency (PAE). Therefore, a low-loss built-in linearizer is developed in the first part of this thesis. The first part of the thesis presents linearized power amplifier at V-band. Four 30 finger 2-μm devices are combined using current combining method in the output stage of the three-stage PA and then adding the pre-distortion linearizer to improve the linear output power of the power amplifier. The circuit is designed in 65-nm CMOS process with 10 dBm P1dB and with PAE 6.0% when linearizer is off. When linearizer is on, the P1dB is improved from 10 dBm to 11.8 dBm and the PAE is 8.8% with 3 dB gain degradation. Phase array system is a future trend for millimeter-wave frequency as the higher directivity and higher array gain can increase signal-to-noise ratio (SNR). Phase shifter and variable gain amplifier (VGA) are both the critical part of the system. However, to reduce the control complexity, phase and amplitude must be control independently. Therefore, a low insertion-loss variation phase shifter and a low phase variation VGA must be developed respectively. The second part of the thesis demonstrates a low insertion-loss variation phase shifter at 22 GHz with over 330∘continuously phase tuning range from 21-25 GHz in standard 0.18-μm CMOS technology. This phase shifter is composed of a 180∘continuously phase tuning range reflection-type phase shifter (RTPS) and a 180∘discrete switch-type phase shifter (STPS). The measured phase shift range is 336∘at 22 GHz with small loss variation of 1.3 dB at 22 GHz and the maximum insertion loss at 22 GHz is 16 dB.