In this work, a single-band power amplifier (PA) with a fixed-frequency/band output matching network and multiband PA with a switch-tuned output matching network is designed, using IHP (Innovations for High Performance), 0.25 lm-SiGe HBT process. The behavior of the amplifiers has been optimized for 2.4 GHz (WLAN), 3.6 GHz (UWBWiMAX), and 5.4 GHz (WLAN) frequency bands for a higher 1-dB compression point and efficiency. Multiband characteristics of the amplifier were obtained by using a MOS-based switching network. Two MOS switches were used for tuning the band of the output matching network. Postlayout simulations of the multiband-PA provided the following performance parameters: 1-dB compression point of 25.2 dBm, gain value of 36 dB, efficiency value of 12.8% operation and maximum output power of 26.8 dBm for the 2.4 GHz WLAN band, 1-dB compression point of 25.5 dBm, gain value of 32 dB, efficiency value of 13.3% and maximum output power of 26.6 dBm for the 3.6 GHz UWB-WiMAX band and 1-dB compression point of 24.8 dBm, gain value of 23 dB, efficiency value of 12.5% and maximum output power of 26.3 dBm for the 5.4 GHz WLAN band. For the fixed-band, at 3.6 GHz, the postlayout simulations resulted the following parameters: 1-dB compression point of 25.5 dBm, gain value of 32 dB, efficiency value of 18% and maximum output power value of 26.8 dBm. Measurement results of the single-band PA provided the following performance parameters: 1-dB compression point of 20.5 dBm, gain value of 23 dB and efficiency value of 7% operation for the 2.4 GHz band; 1-dB compression point of 25.5 dBm, gain value of 31.5 dB and efficiency value of 17.5% for the 3.6 GHz band; 1-dB compression point of 22.4 dBm, gain value of 24.4 dB and efficiency value of 9.5% for the 5.4 GHz band. Measurement results show that using multistage topologies and implementing each parasitic as part of the matching network component has provided a wider-band operation with higher output power levels, above 25 dBm, with SiGe:C process. These results proved that the PA, with switching/tunable output matching network, provides compatible performance parameters, when compared with the fixed-band PA. The ability of being capable of operation in different frequency bands with compatible performance parameters, when compared with fixed-band PA, multiband PA can be realized with additional less parasitics, area, and cost advantages.