Control & Interface for a High Frequency Arbitrary Waveform generator

Abstract

In the REstore Voiding Urinary rEtention (REValUE) project, a high frequency stimulator is designed that should be able to determine the optimal parameters to block the urethral sphincter. In this report the design of the control, interface, current source and electrode switching circuit of the device is explained – the other parts are explained in the reports of the waveform and safety subgroup [1, 2]. The 2,304 cm3 high frequency stimulator has an adjustable frequency (0-15 kHz with 1 kHz step-size), amplitude (0-10mAwith 0.1mAstepsize), pulse width (0-500 ¹s with 1 ¹s step-size) and interphase delay (0-1000 ¹s with 2 ¹s step-size). Two 4-electrode leads of can be connected in mono- and bipolar configuration. Integration of a Liquid-Crystal Display (LCD) screen with Inter-Integrated Circuit messaging bus (I2C) on the NXP LPC1343 shows the user the settings of the stimulation parameters. The current source is designed based on a cascode current mirror, implemented with PNP transistors, using active feedback to control the current. The topology is based on a discrete component implementation.