Claims
- 1. A frequency synthesizer, for use with a means for generating two sequences of electrical pulses, one sequence having a delay with respect to the other, comprising:
- a surface acoustic wave device, adapted to receive one of the sequences of electrical pulses from the generating means, comprising:
- a substrate;
- a first set of interdigitated electrodes, disposed on the surface of the substrate, the electrodes receiving the electrical pulses and transducing them to acoustic waves, which traverse the surface of the substrate, the lengths of the electrodes being configured as a function of m, where m is defined by the relation m = R.sup.n mod P, where P is a prime number, R is a primitive root of P, and n = 1, 2, . . . , (P-1); and
- a second set of interdigitated electrodes, approximately P-1 in number, disposed on the surface of the substrate, the electrodes of the first and second sets being parallel, the second set of electrodes being so disposed as to receive the acoustic waves generated by the first set of electrodes, and transduce them back to electrical signals, which are conducted on a set of leads connected to the electrodes;
- the input and output electrodes being so disposed with respect to each other that the signal received from the top parts of the output electrodes has a phase shift 90.degree., at a frequency f.sub.0, with respect to the phase shift of the signal received from the bottom parts of the output electrodes;
- means adapted to receive pulses from the electrical pulse generating means, which selectively receives the electrical signals from the second set of electrodes, the receiving means having as an output a signal whose frequency is determined by the particular cyclic shift of the order in which the signals are received from the second set of electrodes.
- 2. The frequency synthesizer according to claim 1, wherein
- the first set of electrodes, which are input electrodes, comprise two sets of electrodes, an upper and lower set, each set consisting of pairs of electrodes, a pair of one set being parallel to a corresponding pair of the other set, the sum of the lengths squared of each two corresponding pairs of electrodes being a constant.
- 3. The frequency synthesizer according to claim 2, wherein:
- the upper set of input electrodes is so configured as to be offset by one-quarter wavelength from the lower set of input electrodes.
- 4. The frequency synthesizer according to claim 2, wherein:
- the output electrodes are configured so that the upper half of each output electrode is offset by one-quarter wavelength from its corresponding lower half.
- 5. The frequency synthesizer according to claim 2, wherein
- the upper set of input electrodes is configured so as to be offset from the bottom set of input electrodes; and wherein:
- the output electrodes are configured so that the upper half of each output electrode is offset from its corresponding bottom half;
- the total amount of offset for the input and output electrodes being one-quarter wavelength.
- 6. The frequency synthesizer according to claim 2, further comprising:
- the means for generating the two sequences of electrical pulses.
- 7. The frequency synthesizer according to claim 6 wherein:
- the means for generating two sequences of electrical pulses comprises:
- a first means, whose output is connected to the input electrodes, for producing a sequence of pulses at its output; and
- a second means, whose input is connected to the output of the pulse producing means, for delaying the pulses at its input, the output of the delaying means being connected to the input of the selective receiving means.
- 8. The frequency synthesizer according to claim 7, further comprising:
- means, the input of which is connected to the output of the first pulse-generating means, for transmitting the pulse to either of two alternate connections; and wherein
- the first pulse-generating means generates pulses alternately to the upper and lower sets of input electrodes with a time delay, .DELTA.t = 1/4f.sub.0, equivalent to an acoustic delay corresponding to a distance equal to one-quarter wavelength.
- 9. The frequency synthesizer according to claim 8, wherein the receiving means comprises:
- means, adapted to receive the signals from the second set of electrodes which has the same number of inputs as there are pairs of electrodes in the second set of electrodes, the inputs being connected to the electrode outputs;
- means controlling the cyclic shift of the sequence in which the output leads conduct signals; and
- means, adapted to receive input pulses from the pulse-delaying means, and having connections to the output switch, which controls the particular cyclic shift of the sequence by which current is conducted to the output of the selective receiving means.
- 10. The frequency synthesizer according to claim 9, wherein:
- the means adapted to receive input pulses further comprises a set of unilateral conducting devices, one in the output path of each of the pairs of output electrodes, which can be enabled to pass signals through the respective output paths.
STATEMENT OF GOVERNMENT INTEREST
The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
US Referenced Citations (3)
Non-Patent Literature Citations (1)
Entry |
Maines et al. "Surface-Acoustic Wave Devices for Signal Processing Applicons" in Proceedings of The IEEE, vol. 64, No. 5, May 1976, pp. 639-652. |