Microminiature, monolithic, variable electrical signal processor and apparatus including same

• US 5,526,172 A
• Filed: 07/27/1993
• Issued: 06/11/1996
• Est. Priority Date: 07/27/1993
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Kanack, Brad
• Primary Examiner(s): Epps, Georgia Y.
• Assistant Examiner(s): Robbins, Thomas
• Application Number:
  US08/097,824
• Time in Patent Office: 1,050 Days
• Field of Search: 359/290, 359/291, 359/297, 359/315, 359/846, 359/849, 330/7
• US Class Current: 359/291
• CPC Class Codes: H01G 5/16 using variation of distance between electrodes
• CPC Class Codes: H01G 5/18 due to change in inclination, e.g. by flexing, by spiral wrapping
• CPC Class Codes: H01H 1/20 Bridging contacts for circuit breakers H01H73/045
• CPC Class Codes: H01H 2001/0042 Bistable switches, i.e. having two stable positions requiring only actuating energy for switching between them, e.g. with snap membrane or by permanent magnet
• CPC Class Codes: H01H 2001/0084 with perpendicular movement of the movable contact relative to the substrate
• CPC Class Codes: H01H 2059/0018 Special provisions for avoiding charge trapping, e.g. insulation layer between actuating electrodes being permanently polarised by charge trapping so that actuating or release voltage is altered
• CPC Class Codes: H01H 2059/0036 Movable armature with higher resonant frequency for faster switching
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: H01H 67/22 Switches without multi-position wipers
• CPC Class Codes: H01P 1/127 Strip line switches
• CPC Class Codes: H01P 1/184 Strip line phase-shifters H01P1/181, H01P1/185, H01P1/19 take precedence
• CPC Class Codes: H01P 5/04 with variable factor of coupling
• CPC Class Codes: H01P 9/00 Delay lines of the waveguide type

Abstract

A microminiature, variable electrical device, such as a capacitor (40a), comprises an elemental DMD SLM (40'"'"'), which includes a substrate (43) and a member (145) spaced therefrom and mounted for movement by appropriate facilities (42, 44). A control signal (102) is applied to the movable member (145) to produce an electric field between it and either the substrate (43) or an associated control electrode (46a). The field moves the member (145) toward or away from either the substrate (43) or an associated output electrode (46b) to selectively adjust the spacing therebetween. The field is produced by addressing circuitry (45) associated with the substrate (43). The movable member (145) and either the substrate (43) or the output electrode (46b) function as capacitor plates, and the spacing determines the capacitance thereof. The capacitor (40a) may be placed in series (FIG. 4) or in parallel (FIG. 3) with an input signal (114) applied to the movable member (145). The movable member (145), substrate (43), control electrode (46a), output electrode (46b), addressing circuitry (45), and other elements of the capacitor (40a) comprise a monolithic structure resulting from the use of MOS, CMOS or similar fabrication techniques. Multiple capacitors may be included in transmission lines (FIG. 20), antennae (FIG. 22), couplers (FIG. 21), waveguides FIG. 25) and other apparatus for digital or analog tuning or capacitance adjustment thereof by selective operation of the addressing circuitry (45).

Claims

1. A microminiature, monolithic signal processor, comprising:

(a) a variable electrical capacitor, comprising;

(i) a substrate,

(ii) an electrically conductive member monolithically formed with and spaced from the substrate, the respective plates of the capacitor being the member and the substrate,

(iii) means for mounting the member for deflection of a portion thereof toward and away from the substrate and for storing energy when the portion of the member deflects out of a normal position, the stored energy tending to return the deflected portion of the member to the normal position,

(iv) a control electrode monolithically formed with the substrate and the member, the electrode being spaced from the member along the direction of deflection of the portion of the member out of the normal position, the control electrode and the member being capable of having impressed therebetween a control signal sufficient to produce a field therebetween to deflect the portion of the member out of its normal position so as to vary the capacitance of the capacitor, and

(b) signal means applying a time-varying electrical input signal to the signal processor which said input signal is modulated as a function of the capacitance of said variable capacitor.

2. A signal processor as in claim 1, wherein.:

the mounting means comprises a compliant facility centrally supporting the member.

3. A signal processor as in claim 2, wherein:

the compliant facility is a membrane.

4. A signal processor as in claim 3, wherein:

the membrane is an elastomer.

5. A signal processor as in claim 3, wherein:

the membrane is a conductive metal.

6. A signal processor as in claim 1, wherein:

the mounting means comprises a compliant facility integrally formed with the member and the input-signal-applying means.

7. A signal processor as in claim 6, wherein:

deflection of the portion of the member comprises rotation of the member about an axis which is asymmetric relative to the member.

8. A signal processor as in claim 6, wherein:

deflection of the portion of the member comprises rotation of the member about an axis which is symmetric relative to the member.

9. A signal processor as in claim 6, wherein:

deflection of the portion of the member comprises rotation of the member about an axis, and

the field is bounded by the control electrode and the portion of the member, the portion being spaced from the axis.

10. A signal processor as in claim 9, wherein:

the axis is symmetric relative to the member.

11. A signal processor as in claim 9, wherein:

the axis is asymmetric relative to the member.

12. A signal processor as in claim 6, wherein:

the compliant facility includes a torsion spring.

13. A signal processor as in claim 6, wherein:

the compliant facility is a cantilever spring.

14. A signal processor as in claim 6, wherein:

the compliant facility comprises a membrane.

15. A signal processor as in claim 14, wherein:

a portion of the membrane comprises a part of the member.

16. A signal processor as in claim 15, wherein:

the member moves in a piston-like fashion as the portion thereof is deflected toward and away from the substrate.

17. A signal processor as in claim 16, wherein:

the member and the membrane are integral, the membrane having high compliance and the member having low compliance.

18. A signal processor as in claim 17, wherein:

the member is smaller than and is generally centrally located with respect to the membrane.

19. A signal processor as in claim 6, wherein:

the compliant facility comprises a flexure system made up of a plurality of cantilever-torsion springs.

20. A signal processor as in claim 19, wherein:

the member moves in a piston-like fashion as the portion thereof is deflected toward and away from the substrate.

21. A signal processor as in claim 6, wherein:

the complaint facility comprises

means for permitting the member to move in piston-like fashion as the portion thereof is deflected toward and away from the substrate.

22. A signal processor as in claim 6, wherein:

the mounting means further comprises;

an insulative spacer on the substrate and monolithically formed with the substrate, the member and the control electrode, the spacer supporting the compliant facility.

23. A signal processor as in claim 22, wherein:

the insulative spacer defines a portion of a boundary of a well into and out of which the portion of the member moves as it deflects toward and away from the substrate.

24. A signal processor as in claim 23, wherein:

the spacer is a photoresist.

25. A signal processor as in claim 6, wherein:

the mounting means further comprises

an electrically conductive post on the substrate and monolithically formed with the substrate, the member and the control electrode, the post supporting the compliant facility.

26. A signal processor as in claim 25, wherein:

the post defines a portion of a boundary of a well into and out of which the portion of the member moves as it deflects toward and away from the substrate.

27. A signal processor as in claim 26, wherein:

the member and the compliant facility are electrically conductive, the post being electrically continuous with the member via the compliant facility, and

the post is electrically insulated from the substrate.

28. A signal processor as in claim 1, wherein:

the control electrode comprises a region of the substrate.

29. A signal processor as in claim 28, which further comprises:

means for applying the control signal between the substrate region and the member, and

the signal means includes

a conductive input path and a conductive output path both electrically continuous with the member so that the input signal passes through the portion of the member.

30. A signal processor as in claim 29, wherein:

the signal means comprises

the substrate region, and

one of the conductive paths electrically continuous with the member.

31. A signal processor as in claim 30, wherein:

the substrate region is grounded.

32. A signal processor as in claim 31, wherein:

the input signal is time-varying, and

the frequency of the control signal is substantially less than that of the input signal.

33. A signal processor as in claim 32, wherein:

the control signal is substantially non-time-varying.

34. A signal processor as in claim 33, wherein:

the frequency of the input signal is sufficiently high with respect to the resonant frequency of the member so that the portion of the member cannot deflect in response thereto.

35. A variable capacitor which includes the signal processor of claim 32, wherein:

the frequency of the input signal is sufficiently high with respect to the resonant frequency of the member so that the portion of the member cannot deflect in response thereto, and

the frequency of the control signal is sufficiently low with respect to the resonant frequency of the member so that the portion of the member deflects substantially in synchronism therewith.

36. A signal processor as in claim 30, wherein:

the input signal and the control signal are superimposed.

37. A signal processor as in claim 1, which further comprises:

an electrically insulative dielectric layer on the substrate for supporting the control electrode on, and insulating it from, the substrate.

38. A signal processor as in claim 37, which further comprises:

means for applying the control signal between the control electrode and the member, and

the signal means includes

a conductive input path electrically continuous with the member and a conductive output path spaced from the member along the direction of deflection of the portion of the member, the output path being supported on and insulated from the substrate so that the input signal is applied by the portion of the member, acting as one plate of the capacitor, to the output path acting as the other plate of the capacitor.

39. A signal processor as in claim 38, wherein:

the signal means comprises

the control electrode, and

the conductive input path.

40. A signal processor as in claim 39, wherein:

the input signal is time-varying, and

the frequency of the control signal is substantially less than that of the input signal.

41. A signal processor as in claim 40, wherein:

the control signal is substantially non-time-varying.

42. A signal processor as in claim 41, wherein:

the frequency of the input signal is sufficiently high with respect to the resonant frequency of the member so that the portion of the member cannot deflect in response thereto.

43. A variable capacitor which includes the signal processor of claim 40, wherein:

the frequency of the input signal is sufficiently high with respect to the resonant frequency of the member so that the portion of the member cannot deflect in response thereto, and

the frequency of the control signal is sufficiently low with respect to the resonant frequency of the member so that the portion of the member deflects substantially in synchronism therewith.

44. A signal processor as in claim 38, wherein:

the input signal and the control signal are superimposed.

45. A signal processor as in claim 37, wherein:

the substrate is a semiconductor, and the dielectric layer is made of a material selected from the group consisting of an insulative oxide, an insulative nitride and a polymer.

46. A signal processor as in claim 45, wherein:

the semiconductor is silicon or gallium-arsenide, the insulative oxide is a silicon oxide, the insulative nitride is a silicon nitride, and the polymer is an epoxy or an acrylate.

47. A signal processor as in claim 45, wherein:

the output path is supported on and insulated from the substrate by the dielectric layer.

48. A signal processor as in claim 1, wherein:

the substrate comprises a material selected from the group consisting of semiconductors, ceramics, aluminas, diamond and quartz.

49. A signal processor as in claim 1, which further comprises:

means for preventing the member from touching the control electrode when the portion of the member moves toward the substrate.

50. A signal processor as in claim 1, wherein:

the member is generally planar, and

the mounting means mounts the member for generally coplanar, translational movement of substantially the entire member.

51. A signal processor as in claim 50, which further comprises:

a membrane, one portion of which comprises a part of the mounting means and another portion of which comprises a part of the member.

52. A signal processor as in claim 50, wherein:

the member is a substantially rigid plane, and

the mounting means is a flexure system made up of a plurality of cantilever-torsion springs.

53. A signal processor as in claim 1, wherein:

the member is generally planar, and

the mounting means mounts the member for generally rotational movement about an axis remote from the centroid of the member.

54. A signal processor as in claim 53, wherein:

the mounting means is a torsion spring.

55. A signal processor as in claim 53, wherein:

the mounting means is a cantilever spring.

56. An electrical circuit which includes the signal processor of claim 1 and wherein:

the signal means comprises

means for grounding the substrate, and

means for connecting the member to a node of the circuit so that the voltage to ground on the node is applied to the member,

whereby the signal processor is in shunt with the node.

57. An electrical circuit which includes the signal processor of claim 1 and wherein:

the signal means comprises

means for connecting the member to a first node of the circuit so that current into the first node is applied to the member, and

means for connecting the substrate to a second node so that current out of the second node flows from the substrate,

whereby the signal processor is in series with the nodes.

58. An electrical circuit which includes the signal processor of claim 1 and which further comprises:

means for applying to the control electrode a control signal independent of the signal processor-affected input signal.

59. An electrical circuit which includes the signal processor of claim 1 and which further comprises:

means for applying to the control electrode a control signal derived from the signal processor-affected input signal.

60. A signal processor as in claim. 1, wherein:

selected characteristics of the compliant facility are alterable so that the movement of the portion of the member and, hence, the capacitance of the signal processor, both of which are effected by the application of a selected control signal to the control electrode, are adjustable.

61. A signal processor as in claim 60, wherein:

characteristic-alteration of the compliant facility is achievable by selective removal of a portion of the compliant facility.

62. A signal processor as in claim 61, wherein:

selective material removal is achievable by selective application of concentrated radiant energy to the compliant facility.

63. A signal processor as in claim 1, wherein:

the control electrode is a section of the substrate.

64. A signal processor as in claim 1, wherein:

the control electrode is a conductive region formed on the substrate.

65. A signal processor as in claim 64, wherein:

the conductive region is insulated from the substrate.

66. A transmission line which includes one or more signal processors according to claim 1 for varying the impedance thereof.

67. A transmission line as in claim 66 of the variable impedance, microstrip type.

68. An impedance matching network which includes one or more signal processors according to claim 1 for varying the impedance thereof.

70. An antenna which includes one or more signal processors according to claim 1 for varying the impedance and the frequency characteristics thereof.

71. An antenna as in claim 70, wherein:

the member is an element of the radiating or receiving surface of the antenna.

72. An antenna as in claim 71 of the patch type.

73. An antenna as in claim 71 of the spiral type.

74. An antenna as in claim 71 of the slot type.

75. A coupler which includes one or more of the signal processors according to claim 1 for varying the impedance thereof.

76. A coupler as in claim 75 of the symmetric type.

77. A coupler as in claim 75 of the asymmetric type.

78. A coupler as in claim 75 of the rat race type.

79. A waveguide having at least one surface which comprises one or more of the signal processors according to claim 1 for varying the impedance thereof.

80. A fin line including one or more of the signal processors according to claim 1 for varying the impedance thereof.

81. A signal processor as in claim 1, wherein:

the normal position of the member is away from the substrate and when the member is deflected it is closer to the substrate.

82. A signal processor as in claim 1, wherein:

the normal position of the member is toward the substrate and when the member is deflected it is farther from the substrate.

69. A filter network which includes one or more signal processors according to claim I for varying the impedance thereof.

83. A microminiature, monolithic signal processor, comprising:

(a) a variable capacitor, comprising;

(i) a substrate,

(ii) a member monolithically formed with and spaced from the substrate, a region of the substrate and a portion of the member acting as the respective plates of the capacitor,

(iii) means for mounting the member for deflection of the portion thereof toward and away from the substrate region and for storing energy when the portion of the member deflects out of a normal position, the stored energy tending to return the deflected portion of the member to the normal position,

(iv) means for selectively deflecting the portion of the member out of its normal position to vary the capacitance of the signal processor, and

(b) signal means applying a time-varying electrical input signal to the capacitor which said input signal is modulated as a function of the capacitance of said variable capacitor.

84. A signal processor as in claim 83, wherein:

the selective deflecting means includes

means for producing an electric field bounded in part by the portion of the member, the electric field deflecting the portion of the member relative to the substrate by an amount proportional to the magnitude thereof.

85. A signal processor as in claim 84, wherein:

the electric field is produced by a voltage having a frequency such that the portion of the member deflects substantially in synchronism therewith.

86. A signal processor as in claim 85, wherein:

the voltage is non-time-varying.

87. A signal processor as in claim 84, wherein:

the deflection field produced by the field-producing means is bounded in part by the region of substrate.

88. A signal processor as in claim 87, wherein:

the deflection field is produced by a voltage having a frequency such that the portion of the member deflects in synchronism therewith.

89. A signal processor as in claim 88, wherein:

the voltage is non-time-varying.

90. A signal processor as in claim 89, wherein:

the deflection voltage is applied between the substrate and the member.

91. A signal processor as in claim 90, wherein:

the input signal is a voltage having a frequency which is sufficiently high with respect to the resonant frequency of the member such that the portion of the member is incapable of deflecting in response thereto.

92. A signal processor as in claim 91, wherein:

the input voltage is superimposed on the deflection voltage.

93. A signal processor as in claim 92, wherein:

the field-producing means includes

a control electrode associated with the substrate region, which electrode in part bounds the electric field which deflects the portion of the member by an amount determined by the magnitude thereof.

94. A signal processor as in claim 93, wherein:

the electric field is produced by a voltage applied to the control electrode and having a frequency such that the portion of the member deflects substantially in synchronism therewith.

95. A signal processor as in claim 94, wherein:

the deflection voltage is non-time-varying.

96. A signal processor as in claim 95, wherein:

the deflection voltage is applied between the control electrode and the member and the input voltage is applied to the member.

97. A signal processor as in claim 96, wherein:

the control electrode and the mounting means are monolithically formed with the substrate and the member.

98. A signal processor as in claim 97, wherein:

the mounting means comprises

a deformable membrane on which the member resides, and

a support on the substrate to which the membrane is attached.

99. A signal processor as in claim 98, wherein:

the member comprises a first compliance, rigid element residing on the membrane, portions of the membrane surrounding the member having a second compliance higher than that of said first compliance.

100. A signal processor as in claim 99, wherein:

the member and the membrane are electrically conductive and integral and the member is thicker than the membrane.

101. A signal processor as in claim 100, wherein:

the support is a conductive post on and insulated from the substrate.

102. A signal processor as in claim 100, wherein:

the support is an insulative spacer on the substrate.

103. A signal processor of the type set forth in claim 83, wherein:

the selective deflecting means deflects the portion of the member with respect to time, the frequency of such deflection being independent of the frequency of the input signal.

104. A signal processor as in claim 103, wherein:

the frequency of the deflection is smaller than the frequency of the input signal.

105. A signal processor as in claim 103, wherein:

the deflecting means includes

electric field-producing means for producing an electric field which deflects the member out of the normal position.

106. A signal processor as in claim 105, wherein:

the control electrode and the region are substantially coplanar.

107. A signal processor as in claim 103, wherein:

the field-producing means includes

a control electrode which in part bounds the electric field which deflects the portion of the member toward the region by an amount proportional to the magnitude thereof.

108. A signal processor as in claim 107, wherein:

the control electrode and the region are formed on the substrate.

109. A signal processor of the type set forth in claim 83, wherein:

the selective deflecting means deflects the portion of the member with respect to time, the frequency of such deflection being substantially the same as the frequency of the input signal.

110. A signal processor as in claim 109, wherein:

the selective deflecting means is the input signal-applying means.

111. A signal processor as in claim 110, wherein:

the deflection voltage is substantially non-time-varying.

112. A signal processor as in claim 111, wherein:

the segments are insulated from each other and from the substrate.

113. A signal processor as in claim 109, wherein:

the electric field is produced by a voltage applied to the control electrode and having a frequency such that the portion of the member deflects substantially in synchronism therewith.

114. A signal processor as in claim 113, wherein:

the control electrode and the region include

respective interdigitated segments all of which are generally aligned with the portion of the member as it deflects.

115. A microminiature, monolithic signal processor, comprising:

(a) a variable capacitor, comprising;

(i) a substrate,

(ii) a microminiature member monolithically formed with and spaced from the substrate,

(iii) an electrically conductive region spaced from a portion of the member, the region and the portion of the member acting as the respective plates of a parallel plate capacitor,

(iv) means for mounting the member for deflection of the portion thereof toward and away from the region and for storing energy when the portion of the member deflects out of a normal position toward the region, the stored energy tending to return the deflected portion of the member to the normal position,

(v) means for selectively deflecting the portion of the member out of its normal position toward the region to vary the capacitance of the capacitor, and

(b) signal means applying a time-varying electrical input signal to the capacitor which said input signal is modulated as a function of the capacitance of said variable capacitor.

116. A signal processor as in claim 115, wherein:

the deflection voltage is applied between the control electrode and the member and the input voltage is applied between the region and the member.

117. A microminiature, monolithic device, which comprises:

a substrate,

a movable member which in a first normal position affects an input signal in a first mode and which affects the input signal in a second mode when not in the first position,

means for mounting the member at a location spaced from the substrate for movement of the member toward and away from the substrate and for storing energy when the member moves out of the first position, the stored energy biasing the member toward the first position,

means applying a time-varying electrical said input signal to the device,

means for selectively applying a control signal to the member, and

means responsive to the control signal for selectively moving the member out of the normal position to selectively alter the mode in which the member affects the input signal.

118. A device as in claim 117, wherein:

the member is electrically conductive and the application of the control signal thereto produces an electrostatic field acting thereon which moves the member out of the first position relative to the substrate.

119. A variable electrical capacitor which includes a device as in claim 118, wherein:

the member is one plate of the variable electrical capacitor, movement of the member by the electrostatic field altering the capacitance of the capacitor, and

the input signal and the control signal are both applied to the member.

120. A variable electrical capacitor as in claim 119, wherein:

the path taken by the input signal is in parallel with the alterable capacitance of the capacitor.

121. A variable electrical capacitor as in claim 119, wherein:

the path taken by the input signal in series with the alterable capacitance of the capacitor.

122. A device as in claim 118, wherein:

the electrostatic field moves the member toward the substrate.

123. A variable capacitor which includes a device as in claim 118, wherein:

the member is one plate of the variable capacitor, movement of the member altering the capacitance of the capacitor.

124. A variable capacitor as in claim 123, wherein:

the capacitor is in parallel with the input signal.

125. A variable capacitor as in claim 123, wherein:

the capacitor is in series with the input signal.

126. A variable capacitor which includes a device as in claim 118 for use with a time-varying input signal, wherein:

the selective moving means moves the member with respect to time, the frequency of such movement being independent of the frequency of the input signal.

127. A variable capacitor as in claim 126, wherein:

the frequency of the movement is smaller than the frequency of the input signal.

128. A non-linear capacitor which includes a device as in claim 118 for use with a time-varying input signal, wherein:

the selective moving means moves the member with respect to time, the frequency of such movement being the same as the frequency of the input signal.

129. A non-linear capacitor as in claim 128, wherein:

the selective moving means is the input signal-applying means.

130. A waveguide which includes the device of claim 117, wherein:

the movable member forms a coplanar portion of the interior surface of the waveguide in the first position,

movement of the member out of the first position being away from the wall to effectively decrease the cross-section of the waveguide along a line generally parallel to the line of movement of the member.