Breast cancer is the second causes of death among women in Malaysia. The patient can be cured if the breast cancer can be detected and treated at the early stage. Breast imaging system is one of the most popular method to detect tumor in the human body. The current diagnostic techniques have limitations, and one of the major challenges is in achieving low group delay over wide bandwidth in power amplifier. High group delay power amplifier can lead to distorted and inaccurate imaging result, making it difficult for medical professional to make reliable diagnoses. Therefore, low group delay power amplifier over wideband is designed. The CMOS power amplifier design consists of three cascaded amplifier stages with resistive shunt feedback and inductive source degeneration techniques. The second stage is a simple common-source topology to reduce the input broadband matching constraints. The third stage is source degeneration inductor and the output matching involved single capacitor to improve the wideband matching. The CMOS PA BIS design was implemented by using Silterra 0.18µm CMOS technology with the chip size of 1mm2. A low group delay variation of 24.75 ps with frequency of 3.1-7.0 GHz power amplifier for breast imaging system is achieved. With these characteristics especially in achieving low group delay is very suitable for breast imaging system with more accurate and reliable imaging and small chip size allowing medical professionals to detect tumors at earlier stages. Thus, it will increase the chances of successful treatment outcomes and improved patient survival rates.