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Specific integrated circuit IC for power addressing and amplification

In order to drive the different piezoelectric actuators mounted on MiCRoN robots, a 20V trapezoidal (for EPFL actuators) or saw-tooth signal (for DMS actuators) must be generated and applied between the actuator terminals if a deformation of this materials and therefore movement is desired. For this reason, a full-custom mixed-signal IC called PAA (Power Addressing and Amplification IC) has been designed using a 0.7¿Ym BCD (Bipolar, CMOS, DMOS) I2T technology from AMIS semiconductor that allows the inclusion on the same substrate of analogue high voltage transistors and digital CMOS gates.

PAA IC contains 5 high voltage operational amplifiers (HVOA), which are internally set up in an inverting close loop configuration. The gain in each HVOA is fixed with a voltage divider based on integrated resistors. HVOAs have a power down system that it is enabled when the piezoelectric actuator controlled by the selected amplifier does not need to be driven. This fact allows the reduction of the global power consumption of PAA IC. The operation of PAA IC it is the following: a digital control unit decodes the control signals [cs1,cs0,b1,b0] that come from a main digital control unit IC (called MXS) based on a truth table that defines the different actuation modes that a MiCRoN robot can handle depending on the depending on the tool used by the robot.

Since more than five piezoactuators have to be driven, two PAA ICs must be included on the electronics on board (Chip 0 and Chip 1) hence the digital control unit generates 10 internal signals [C9..C0] that enable (active high) or disable the 10 drivers included in Chip 0 and Chip1. An ID signal (Identification Chip) included in PAA IC allows selecting the internal enable/disable signals that will be applied to the five HVOA in each PAA IC. If ID=0, then the enable/disable driver signals are [C4..C0] whereas if ID=1 the enable/disable driver signals are [C9..C5]. This fact, allow us to implement a different control for the 5 HVOAs of Chip 0 or Chip 1 only setting up a different value for ID without any modification of the PAA IC design.

When any driver on Chip 0 or Chip 1 is enabled (due to [cs1,cs0,b1,b0] from MXS) the digital control unit generates a RQ signal (Request signal) which means that the robot wants to make any operation with one of its tools. The RQ signals enables the awaking unit (but only in the PAA Chip where a HVOA has been enabled following the actuation mode truth table) that generates also an AWK signal (Awake signal) that goes to the start up unit. This unit starts a low slew-rate bias of the activated drivers in order to avoid great peak currents at the beginning that could damage the HVOAs. Once the selected amplifier/s are properly biased and ready to start their activity, the start up unit sends and ACK signal (Acknowledge signal) to MXS IC indicating that MXS IC can send low voltage (1V up to 2.4V) trapezoidal or saw-tooth signals that will be amplified (up to 20V) and applied to the selected piezoelectric actuators. The maximum working frequency of the amplified signals has been fixed to 1kHz for DMS material and 3kHz for EPFL.

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Reported by

Instrumentation and Communications Systems SIC Lab
1,University of Barcelona Electronics Department 1, Marti i Franques
08028 Barcelona
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