Gain adjustment
The amplifier can be adjusted by a software tool from the manufacturer which allows to select and change the gain of each channel separately. It is important to identify the amplitude generated by the DDS. In order to be able to give a reliable statement about the phase shift, it is necessary to work with an amplitude of approximately 0.5 V, since the components on our PCB operate with this voltage. Since the signal is doubled once for a reference measurement and once for our sensing chip, the amplitude decreases due to this operation and has to be amplified to approx. 0.5 V again.
To control the amplifier, it first needs to be powered by a 5 V supply voltage. We recommend exchanging the already soldered plugs for the supply voltage with pin headers, otherwise there is the risk of a short circuit. Moreover, the pin headers offer a direct connection to the GPIO of the Arduino, which delivers the supply
voltage for the amplifier. Next the included USB cable can be connected to the computer.
After installing the software we first checked if the amplifier really increases the signal or whether there are difficulties with the configuration. In our case there was an incorrect configuration in the "Low Level View" menu. Two states required to be switched on 0, afterwards the amplifier could be controlled. The proper settings can also be found in the data sheet.
In order to achieve an amplitude of at least 0.5 V, we have to adjust the gain to 13 which results in an amplification by the factor 10
13. The settings are saved in the device's buffer memory, meaning that this step only requires a single adjustment. The images below illustrate the effect of the amplifier on the amplitudes.