In this paper it is presented the design of the power supply system for an autonomous robot of few mm3 called I-SWARM
(Intelligent Small World Autonomous Robots for Micro-manipulation) which is based on the design of a low-dropout
regulator (LDO), and a bandgap reference circuit (BG), that has been designed for the LDO. The paper presents
the design, stability issues and full Montecarlo studies about the performances of the BG circuit and the LDO regulator,
for different temperature and supply conditions. The regulator has been developed to supply the required voltage for the
electronics involved in the robot to be tested in a near future. The regulator is based on a low-dropout linear regulator
(LDO). The architecture of the BG is based on a peaking current mirror circuit with MOSFET transistors, working in the
sub-threshold region. This architecture is very interesting because it presents a good trade-off between performances,
area and power dissipation. These circuits have been designed in a 0.13 &mgr;m technology from ST Microelectronics
through the CMP-TIMA service.
An efficient 2-stage charge pump based on two-phase voltage doublers is proposed in this paper. Pulse skipping frequency regulators have been used to obtain a high efficiency over a wide range of loads. Since this charge pump has been designed for battery-powered portable devices, a power-up control system that combines a linear and a switched charging sequence has been included in each stage in order to avoid great current spikes at the beginning of the start-up process that could damage or shorten the battery life.
The result is a power efficient 2-stage charge pump capable to generate a maximum regulated output voltage up to 10V from a 2.7V-3.3V battery source and deliver a maximum power of 100mW. If it is desired, the regulated output voltage can be downscaled to a required lower regulated voltage through a simple programming method using external resistors plus internal digital circuitry. This circuit has been designed using a 0.7μI2T technology from AMI semiconductor.