The loss of physiological functions can be restored partially or completely using functional electrical
stimulation and this mechanism has been used in a number of biomedical devices such as the mo-
tor nerves stimulator , pacemaker, urinary implant , and cochlear implant . The advance in
microelectronic technologies is allowing the researchers to engineer highly miniaturized implantable
integrated microsystems . Some of these implantable advanced prosthetic devices use intracorti-
cal functional electrical microstimulation for recovering diseases such as Parkinson and epilepsy .
Another serious dysfunction, called blindness, may be caused by some diseases that affect the ocu-
lar structures, such as glaucoma, age related macular degeneration, and retinitis pigmentisa, rendering
eyes insensitive to light. The visual function can be restored partially using device-based prosthetic
approach. Until now, most of the visual electrical microstimulation devices use an array of metallic mi-
croelectrodes for generating phosphenes in the form of perception of points of light in the visual field.
Figure 1: The global architecture of the proposed microstimulator dedicated for visual intracortical microstimula-
tion. The stimulation module is compatible for driving 16 microelectrodes. The electrode matrix is not part of the
proposed system. 1.2 and 3.3 Volts supplies are for the low voltage analog and digital components to be used in
both IBM CMOS 0.13μm and DALSA 0.8μm 5V/20V CMOS/DMOS technologies. ± 10/13.2 Volts supplies are
for the high voltage sections designed in DALSA 0.8μm 5V/20V CMOS/DMOS technology.
The locations for effective restoration of sight are the retina, the optic tract, the optic nerve, the optic
radiation, the dorsal lateral geniculate nucleus (LGN) of the thalamus, and the primary visual cortex
. Among these locations, retina and primary visual cortex are the most used ones. Retinal implants
 are used to treat only those diseases where the optic nerve and the central visual pathways remain
undamaged. The second approach, intracortical implants, encompasses a large number of diseases to
treat and this advantage has made this approach very attractive in visual prostheses. A large number
of electrodes can be implanted in the primary visual cortex due to its large physical extent, which is
expected to allow the restoration of a very high resolution visual function. Researchers have paid atten-
tion to this area since the work of Brindley . They have studied the visiotopic mapping between the
stimulation sites and the phosphene positions in the visual field , the stimulation parameters  and
chronic implantation of microelectrode arrays in the V1 area .
The general architecture for a visual prosthetic device involves processing the real world images by
an image sensor and transmitting the data using radio frequency (RF) inductive link to the implantable
device. Power is usually supplied by...