Patent ID: 7653118

Claim:
A communications system, comprising: a surface acoustic wave (SAW) expander based transmitter, wherein the transmitter comprises: a baseband controller for coding an input signal and providing an output signal to a switching network; a reference oscillator for providing a plurality of reference signal pulses to the switching network; first and second chirp expanders coupled to the switching network to receive input pulses for forming first and second chirped signals; and a combiner circuit for combining the first and second chirped signals into a transmit signal; wherein at least one of the chirp expanders includes: an input interdigital transducer (IDT) having a plurality of input symbol segments to enable phase coding of the input signal, wherein the input IDT comprises fingers having top and bottom ends, wherein the fingers are slanted with the top ends directed to a common focal point, the top ends have a constant minimum width, and the bottom ends have a constant maximum width; and wherein individual input symbol segments comprise a first group of said fingers extending from an upper bus bar towards a lower bus bar, and a second group of said fingers extending from the lower bus bar towards the upper bus bar, fingers in the first group of fingers interdigitated with fingers in the second group of fingers, fingers in the first group of fingers having top ends connected to said upper bus bar, and fingers in the second group of fingers having bottom ends connected to said lower bus bar.