Receiver design simplified by SAW coupled resonator filters

Abstract

An improvement in conventional superheterodyne receiver systems has been realized through a use of low-loss surface acoustic wave (SAW) filters. With SAW technology, single-conversion VHF-UHF receivers can now be easily implemented. The problem of image and spurious signal rejection when converting directly from VHF and UHF ranges to low intermediate frequencies, such as 455 kHz, is solved by the high-performance two-pole SAW coupled resonator filters with selective null placement. A two-channel guard receiver is presented that illustrates this technology. The guard receiver achieves a 10 dB S+N/N sensitivity of -110.5 dBm and an image frequency rejection of greater than 80 dB.<>