CDMA communication RF signal processing apparatus using SAW

A surface acoustic wave signal processing apparatus for processing first and second high-frequency signals which are a spread-spectrum signal having a frequency f.sub.RF and a non-modulation signal having a frequency f.sub.LO respectively so that each of said frequencies f.sub.RF and f.sub.LO are equal to a frequency f except the broadening of the spectral bandwidth due to modulation (that is, f.sub.RF .apprxeq.f.sub.LO .apprxeq.f), said apparatus comprising:

• a first surface acoustic wave delay element having N output terminals at which phase delays in outputs are .phi..sub.1 (1), .phi..sub.1 (2), . . . , .phi..sub.1 (N) respectively;
• a second surface acoustic wave delay element having N output terminals at which phase delays in outputs are .phi..sub.2 (1), .phi..sub.2 (2), . . . , .phi..sub.2 (N) respectively so that said phase delays in outputs at said output terminals of said second surface acoustic wave delay element are substantially equal to said phase delays in outputs at said output terminals of said first surface acoustic wave delay element respectively correspondingly (that is, .phi..sub.1 (1).apprxeq..phi..sub.2 (1), .phi..sub.1 (2).apprxeq..phi..sub.2 (2), . . . , .phi..sub.1 (N).apprxeq..phi..sub.2 (N));
• a third surface acoustic wave delay element having N output terminals at which phase delays in outputs for said frequency f are .phi..sub.3 (1), .phi..sub.3 (2), . . . , .phi..sub.3 (N) respectively with phase differences of about 90.degree. from those in said second delay element (that is, .phi..sub.2 (1).apprxeq..phi..sub.3 (1).+-.90.degree., .phi..sub.2 (2).apprxeq..phi..sub.3 (2).+-.90.degree., . . . , .phi..sub.2 (N).apprxeq..phi..sub.3 (N).+-.90.degree.);
• and independent N mixers in which the differences (.vertline..phi..sub.1 (1)-.phi..sub.1 (2).vertline., .vertline..phi..sub.1 (2)-.phi..sub.1 (3).vertline., . . . , .vertline..phi..sub.1 (N-1)-.phi..sub.1 (N).vertline., .vertline..phi..sub.2 (1)-.phi..sub.2 (2).vertline., .vertline..phi..sub.2 (2)-.phi..sub.2 (3).vertline., . . . , .vertline..phi..sub.2 (N-1)-.phi..sub.2 (N).vertline. and .vertline..phi..sub.3 (1)-.phi..sub.3 (2).vertline., .vertline..phi..sub.3 (2)-.phi..sub.3 (3).vertline., . . . , .vertline..phi..sub.3 (N-1)-.phi..sub.3 (N).vertline.) between phase delays in outputs at adjacent ones of said N output terminals in each of said delay elements are substantially equal to a value 2 .pi.f times as large as the length Tc of each chip constituting a unit spread code row (corresponding to a unit symbol) of a spread-spectrum signal or to an integer (K) multiple of said value 2 .pi.f times as large as the length Tc of each chip;
• said first and second high-frequency signals are inputted to said first and second delay elements, and first and second high-frequency output signals respectively obtained from corresponding terminals of said first and second delay elements are mixed by said independent N mixers so that N modulation signals (l(1), l(2), . . . , l(N)) which are equal to differential frequencies respectively, that is, which are of a base band, are taken out independently from said N mixers;
• and a third high-frequency signal which is the same signal as said second high-frequency signal is inputted to said third delay element, and first and third high-frequency output signals respectively obtained from corresponding terminals of said first and third delay elements are mixed by said independent N mixers so that N modulation signals (Q(1), Q(2), . . . , Q(N)) which are equal to differential frequencies respectively, that is, which are of a base band, are taken out independently from said N mixers.