Self-configurable decade box: Design and measurements

This paper describes and validates an electronic circuit designed to automize a simple PLL (Phases Locked Loop) architecture circuit. In the developed application, the automatic feature means that the system is reading the output, interpreting the result and applying a certain value of delaying or forwarding element, in our case a low-pass / high- pass filter. In order to compensate different signal delays, multiple values of capacitors and resistors will be implemented into two separate “automated decade boxes”. The application will be controlled by an intelligent circuit, in our case being represented by a micro controller system. The reaction of the system is permanently analyzed by the monitoring sub-system. The main function of the application is to detect the delay between the input signal and the reference signal and to compensate it with right value of the all-pass filter. [2], [5] The theoretical part is presenting the state of the art and the design of the main circuit based on the theoretical formulas and calculation. The architecture of a PLL circuit is presented and analyzed. The abstraction level is covering all levels, starting from system overview, block diagrams, sub- systems and then to component level. The simulation part is presenting different environments like LTSpice, KiCad & LabView to get a first estimation over the outputs. To measure the real values, a test board was developed to prove the functionality of the circuit. Measurements have been performed using different laboratory setups which are presented in a more detailed manner in the article. The results were centralized in a database which was used to determine the best configuration of the filtering (PLL architecture) circuit to synchronize the two analog signals. Besides the identified application in the area of electronic system testing, new potential uses cases have been identified in the area of telecom and mobile networks, simple IC synchronizing applications or dynamic filtering.