An analog frontend of an implantable baseband SOC (System-on-a-chip) chip design for the interface of neural micro-stimulation is present in this thesis. The mentioned neural interface including controllable stimulators, and telemetry for data and power transmission which is powered by transcutaneous magnetic coupling. An external transmitter coil is required to power and communicate with the implanted device. It can avoid the risk of causing infection and the problem of limited battery life. The first topic of this thesis proposes a single stage differential amplifier to be used as an Error Amplifier in an LDO (Low Dropout) regulator. It increases the bandwidth and decreases the chip¡¦s area at the same time. When a bandgap bias is integrated with our design in a feedback loop, a stable voltage source is constituted to become a power supply for the entire implanted chip. The second topic reveals a C-less (no capacitor) area-saving ASK (Amplitude Shift keying) demodulator. Since there is no capacitor used in the demodulator, it can substantially reduce the layout area of the SOC without any sacrifice of the performance of the SOC

This thesis proposes a multi-parameter implantable micro-stimulator system. By using wireless communication and the muli-parameter control, the infection caused by the wound could be avoided and various stimulation waveforms could be generated for different bio-medical applications. Besides, a graphic user interface (GUI) is implemented for the proposed micro-stimulator for the convenience of usage. Moreover, the in vitro experiments are carried out, where the neurons could be stimulated successfully. To reduce the system area caused by external capacitors required by traditional ASK demodulators, a C-less ASK demodulator is proposed in this thesis. A bias-based envelope detector and a Schmitt trigger are used for demodulation. Moreover, by enlarging the noise margin of the envelope detector, an all-MOS ASK demodulator is carried out such that no passive element is needed and the system area could be further reduced. Besides, two high sensitivity voltage-to-frequency (VFC) are proposed for the full duplex transmission. By using a voltage-to-current converter, a charge and discharge circuit, and an all-MOS voltage window comparator 1 (VWC1), a high sensitivity VFC1 is accomplished. Moreover, a linear VFC2 is also proposed by including a fast all-MOS voltage window comparator, VWC2. Finally, a wide range I/O buffer is proposed for the interface of the implantable micro-stimulator system. With the stacked PMOS and NMOS output stage and the dynamic gate bias generator, high voltage and low voltage signals (VDDH and VDDL) could be transmitted and received without any gate-oxide overstress and leakage currents.