A 0.18 µm CMOS Binary Frequency Shift Keying Modulator with a novel frequency synthesizer structure is proposed in this paper. Based on an analog adder technique being the backbone of the synthesizer, this prototype demonstrates a compact modulator with low complexity, which achieves 1 Mbps at 400 MHz while dissipating 3.1 mW at 1.5 V supply. The proposed design is ideal for biomedical sensor network systems including distributed wearable body area network.