This paper presents a current stimulator with adjustable input at 14bit resolution. The input control is sensitive for brain stimulation, and the number of stimuli per waveform and the duty cycle of the stimulus can be adjusted to produce various waveforms for proper situation. The current stimulator has 4 channels, each of two cannels in uni-directional mode and bi-directional mode. The converter is implemented in a TSMC 0.18um BCD process.