Design of Frequency Discriminator for Ringer Using 0.18 μm CMOS Technology
Chan Hui Shan, Arjuna Marzuki · International Journal of Engineering and Technology · 2009
Ring frequency discriminator is an electronic system that can check the frequency of any incoming signal whether it is in the frequency band or not. It is also one of the features for CMOS Speech and Ringer integrated circuit (IC) that can perform all the necessary speech and line interface functions for telephone sets. The signal is considered as a valid signal if it has frequencies between 20 Hz and 60 Hz (20 Hz < ring frequencies < 60 Hz). For future work, it is also possible to design a ring melody generator. Once the valid ring signal is detected and is present for about 75 ms (depends on the designer) continuously, the melody generator will be activated, the ring signal will be monitored continuously and the melody generator will be immediately turn on or off according to the momentary presence of a valid or invalid ring signal respectively until next power on reset or off-hook. This work is implemented using Silterra 0.18 μm CMOS technology.