Novel frequency discriminators determining simultaneous signals using multi-channel filters

Novel frequency discriminator for IFM receiver having the simultaneous signals determination capability is presented for the first time. The proposed discriminator is designed for 62.5MHz frequency resolution over a frequency range of 2GHz to 4GHz. The discriminator uses five 4-channel and three 5-channel filters for simultaneous signals detection. Tri-mode resonators with two transmission zeros on both sides of the pass-band are employed in implementation of three order band-pass filters. Each of filters with almost 2.5dB insertion loss has 250MHz bandwidth. A distributed coupling technique is utilized to locate the filters in multi-channel filters structure. This technique benefits some features such as reduced insertion loss, compact size and eliminating the matching networks needed in conventional structures.