Surface wave delay line structures having reduced temperature coefficient of delay time

Claim 2

In combination: a surface wave vibratory transmission medium having at least one substantially smooth surface and different tempeRature coefficients of velocity for different directions of propagation of surface waves therein comprising a rotated Y-cut crystal, said propagation of surface waves being substantially along the X axis of said crystal, and the rotation angle of said crystal being between 39- 1/2 * and 46- 1/2 * first means for coupling electrical signals to a first region of said surface directly as surface waves for propagating waves in said medium substantially adjacent said surface of said medium; and second means coupled to a second region of said surface for extracting signals from said surface waves, the amount of coupling between said first and second means being different for different frequencies.

Claim 3

The combination in accordance with claim 1 wherein said first and second means comprise interdigital structures.

Claim 4

The combination in accordance with claim 2 wherein said medium comprises quartz.

Claim 5

The combination in accordance with claim 3 wherein: said first means comprise a plurality of interdigital fingers in which the spacing between adjacent fingers varies as a predetermined function of distance along said X axis.

Claim 6

In combination: a surface wave vibratory transmission medium having at least one substantially smooth surface and different temperature coefficients of velocity for different directions of propagation of surface waves therein comprising a rotated Y-cut crystal, said propagation of surface waves being substantially along the X axis of said crystal, and the rotation angle of said crystal being between 39- 1/2 * and 46- 1/2 *; first means for coupling electrical signals to a first region of said surface directly as surface waves for propagating waves in said medium substantially adjacent said surface of said medium in a direction having a temperature coefficient of velocity which is less than 25 parts per million per degree centigrade over the operating temperature range of said medium; second means coupled to a second region of said surface for extracting signals from said surface waves and; means for feeding back at least a portion of the signals extracted by said second means to said first means.

Claim 7

In combination: a surface wave vibratory transmission medium having at least one substantially smooth surface and different temperature coefficients of velocity for different directions of propagation of surface waves therein comprising a rotated Y-cut crystal, said propagation of surface waves being substantially along the X axis of said crystal, and the rotation angle of said crystal being between 39- 1/2 * and 46- 1/2 *; first means for coupling electrical signals to a first region of said surface directly as surface waves for propagating waves in said medium substantially adjacent said surface of said medium in a direction having a temperature coefficient of velocity which is less than 25 parts per million per degree centigrade over the operating temperature range of said medium; second means coupled to a second region of said surface for extracting signals from said surface waves and; means for feeding back at least a portion of the signals extracted by said second means to said first means.

Claim 8

The combination in accordance with claim 5 wherein said first and second means comprise input and output coupling structures having interdigital fingers wherein the spacing between said interdigital fingers is varied.

Claim 9

The combination in accordance with claim 5 wherein said first and second means comprise interdigital structures.

Claim 10

The combination in accordance with claim 7 wherein said interdigital structures are positioned adjacent said medium and is piezoelectrically coupled to said surface waves.

Claim 11

The combination in accordance with claim 8 wherein said medium comprises quartz.

Claim 12

In combination: a surface wave vibratory transmission medium; means for propagating surface waves in said medium in a direction having a temperature coefficient of velocity which is less than 25 parts per million per degree centigrade over the operating temperature range of said medium; said propagating means comprising an interdigital structure positioned adjacent said medium and piezoelectrically coupled to surface waves in said medium; said medium comprising quartz; said propagation of surface waves being substantially along the X axis of a rotated Y-cut crystal; said propagating means comprising a signal input structure and a signal output structure; and means for recirculating the signal between said output structure and said input structure through a shift register.

Claim 13

In combination: a surface wave vibratory transmission medium; means for propagating surface waves in said medium in a direction having a temperature coefficient of velocity which is less than 25 parts per million per degree centigrade over the operating temperature range of said medium; said propagating means comprising an interdigital structure positioned adjacent said medium and piezoelectrically coupled to surface waves in said medium; said medium comprising quartz; said propagation of surface waves being substantially along the X axis of a rotated Y-cut crystal; said propagating means comprising a signal input structure and a signal output structure; and means for recirculating the signal between said output structure and said input structure through a shift register.

Claim 14

In combination: a surface wave vibratory transmission medium; means for propagating surface waves in said medium in a direction having a temperature coefficient of velocity which is less than 25 parts per million per degree centigrade over the operating temperature range of said medium; said propagating means comprising an interDigital structure positioned adjacent said medium and piezoelectrically coupled to surface waves in said medium; said medium comprising quartz; said propagation of surface waves being substantially along the X axis of a rotated Y-cut crystal; said propagating means comprising a signal input structure and a signal output structure; and means in said medium for directly coupling said surface waves from one path in said medium to an adjacent path in said medium.

Claim 15

In combination: a surface wave vibratory transmission medium; means for propagating surface waves in said medium in a direction having a temperature coefficient of velocity which is less than 25 parts per million per degree centigrade over the operating temperature range of said medium; said propagating means comprising an interDigital structure positioned adjacent said medium and piezoelectrically coupled to surface waves in said medium; said medium comprising quartz; said propagation of surface waves being substantially along the X axis of a rotated Y-cut crystal; said propagating means comprising a signal input structure and a signal output structure; and means in said medium for directly coupling said surface waves from one path in said medium to an adjacent path in said medium.

Claim 16

In combination: a surface wave vibratory transmission medium; means for propagating surface waves in said medium in a direction having a temperature coefficient of velocity which is less than 25 parts per million per degree centigrade over the operating temperature range of said medium; said propagating means comprising an interdigital structure positioned adjacent said medium and piezoelectrically coupled to surface waves in said medium; said medium comprising quartz; said propagation of surface waves being substantially along the X axis of a rotated Y-cut crystal; said propagating means comprising a signal input structure and a signal output structure; and said input and output coupling structures comprising a series to parallel shift register.

Claim 17

In combination: a surface wave vibratory transmission medium; means for propagating surface waves in said medium in a direction having a temperature coefficient of velocity which is less than 25 parts per million per degree centigrade over the operating temperature range of said medium; said propagating means comprising an interdigital structure positioned adjacent said medium and piezoelectrically coupled to surface waves in said medium; said medium comprising quartz; said propagation of surface waves being substantially along the X axis of a rotated Y-cut crystal; said propagating means comprising a signal input structure and a signal output structure; and said input and output coupling structures comprising a series to parallel shift register.

Claim 18

In combination: a surface wave vibratory transmission medium; means for propagating surface waves in said medium in a direction having a temperature coefficient of velocity which is less than 25 parts per million per degree centigrade over the operating temperature range of said medium; said propagating means comprising an interdigital structure positioned adjacent said medium and piezoelectrically coupled to surface waves in said medium; said medium comprising quartz; said propagation of surface waves being substantially along the X axis of a rotated Y-cut crystal; said propagating means comprising a signal input structure and a signal output structure; and said coupling structures comprising a digital phase modulator or detector.

Claim 19

In combination: a surface wave vibratory transmission medium; means for propagating surface waves in said medium in a direction having a temperature coefficient of velocity which is less than 25 parts per million per degree centigrade over the operating temperature range of said medium; said propagating means comprising an interdigital structure positioned adjacent said medium and piezoelectrically coupled to surface waves in said medium; said medium comprising quartz; said propagation of surface waves being substantially along the X axis of a rotated Y-cut crystal; said propagating means comprising a signal input structure and a signal output structure; and said coupling structures comprising a digital phase modulator or detector.

Claim 20

The combination in accordance with claim 13 wherein said medium comprises lithium tantalate.

Claim 21

The combination in accordance with claim 14 wherein said medium constitutes an X-cut crystal.

Claim 22

The combination in accordance with claim 15 wherein the direction of propagation of signal waves is substantially along a rotated Y axis.

Claim 23

The combination in accordance with claim 16 wherein the rotation of said Y axis is in the range of -60 to -90*.