• AMS
• design
• analog
• H-BRIDGE

Abstract
The great development of the automotive industry that has experi-
enced in recent years has developed electronics applications inside a car
that currently are many and extremely diversied, many however, now
so deeply rooted, that the passengers who daily they benet never no-
tice their benets. This thesis was developed within Austriamicrosystems
design centre of Navacchio in Pisa, automotive section, using CMOS 0.35
m high-voltage technology. The growth of the market and the demands of
the same, in fact, lead to the conception and implementation of more ad-
vanced technologies, which combine robustness and reliability with sizes
as low as possible. Within the automotive sector, the work of this thesis is
the full-custom design of analog cells for diagnostics of an H-BRIDGE. In
fact, the number of electric motors inside a common car is considerable, it
may even reach eighty if it's considered vehicles of higher categories. This
wide use leads to the necessity of suitable control circuits, which present
good characteristics of reliability. The classic mechanism of driving a mo-
tor based on the use of a bridge switches, which until some years ago was
implemented exclusively through discrete components, now the modern
technologies allow to integrate it together with the control logic, at least
for currents not too high. A complete circuit for the control of the motors
is instead constituted by a complex system, which has its most important
part in a controller, typically a digital microcontroller since some years.
Several control, monitoring and safety devices operate around it. First
of all they are appropriate drivers, which will have to drive the gate of
the MOSFET of the bridge. There are also circuits of protection against
over-voltage and reverse power, voltage regulators, charge pumps, tem-
perature sensors, often circuits for the PWM control. It is almost always
present a device for limiting the current in the motor, as well as a circuit
for its detection, since knowing the current measurement is essential in
the control of a motor, since it is directly proportional to the torque. The
thesis is divided into the following four chapters:
 The rst chapter represents a kind of introduction to what is the
world of automotive electronics, showing the environment in which the
circuits designed are used, focusing primarily on the largest technological
development of recent years.
 The second chapter introduces the H-Bridge circuit, analyzing it in
all its parts and highlighting the key aspects for the design.
 In the third chapter is presented the problem of the current meas-
urement in the bridge focusing the attention to a possible design solution
based on customer specications.
 The fourth chapter present a complete full custom design of a vds
monitor cell, starting analyzing the customer specications, describing
the functionality of the schematic, then showing simulation and results
compared with the customer specication and nally realizing the layout
of the entire cell.