High Spectral Purity Sinusoidal Voltage Signal Source for Neuromodulation in the Frequency Range from 1 Hz to 500 Khz

The sinusoidal voltage signal source for operation in the frequency range from 1 Hz to 500 kHz is designed. The proposed system consists of an AD9833 integrated waveform generator and a two-stage amplifier based on low-offset voltage operational amplifiers in feedback topologies. It is designed for driving the transconductance amplifier required to generate the sinusoidal current signal for specially designed coils for neuromodulation by generating the sinusoidal magnetic field. The topology of the signal source is explained theoretically and tested in the Keysight Advanced Design System simulation software. A printed circuit board is designed for the signal source. The characterization of the designed electronic circuit is performed. The sinusoidal voltage source presented has a negligible direct current (DC) offset and achieves high spectral purity over the entire frequency range of interest, which is particularly important for the application. The user controls the frequency of the output voltage signal via the Serial Peripheral Interface (SPI), while the amplitude is set manually via the analog potentiometer resistor, as desired for the application. The maximum amplitude of the output signal achieved over the frequency range of interest from 1 Hz to 500 kHz exceeds 200 mV peak-to-peak as required for the application.