Bio-medical implantable devices have appeared for more than fifty years. With more understandings of neuroscience, some diseases caused by neural abnormal discharge or disable may be cured or improved by neural stimulation techniques. Most of the wireless implantable devices transmit power and data into the no-battery implantable device by magnetic coupling. This paper presents an efficient power and data transmission, including LDO power regulator and ASK demodulator for biomedical implantable devices. The modulation index and rate are relative to power transmission efficiency. Results show that with a 2 MHz carrier, the proposed ASK demodulator structure has a maximum modulation index up to 2.86% and a 50% maximum modulation rate. The modulation index is also tunable for different applications. The power regulator provides a stable 1.8 V for the ASK demodulation. This design uses TSMC 0.18 um 1P6M CMOS technology.