We propose a low-power and compact 25-Gb/s differential CMOS modulator driver. To achieve low power consumption, we employ an output driver with a high-gain single-stage amplifier and a gainless pre-driver with an equalizer function. In the pre-driver, we use area-efficient 3D inductors for the inductor peaking technique to obtain the equalizer function with compactness. We also employ a cascode amplifier consisting of high-voltage and standard MOSFETs to output a large voltage swing in CMOS technology. The proposed driver was fabricated in 65-nm 1P9M standard CMOS. It exhibits a data rate of 25 Gb/s, a differential output swing of 3.3 Vpp with an input swing of 300 mVpp, and power consumption of 480 mW with 1.2-/3.3-V dual supplies. The active area is only 0.029 mm2, including all inductors. The results indicate that the best power efficiency, which is 26 % better than the state of the art, and good power consumption versus output swing FoM (mW/Vpp) are achieved.