Method and apparatus for filtering signals in a subsystem including a power amplifier utilizing a bank of vibrating micromechanical apparatus

• US 6,593,831 B2
• Filed: 04/20/2001
• Issued: 07/15/2003
• Est. Priority Date: 01/14/1999
• Status: Expired due to Term

• Current Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Inventors: Nguyen, Clark T. -C.
• Primary Examiner(s): Summons, Barbara
• Application Number:
  US09/839,101
• Publication Number:
  US 20020041220A1
• Time in Patent Office: 816 Days
• Field of Search: 333/133, 333/186-192, 333/197, 333/198
• US Class Current: 333/133
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: H03H 2009/02511 Vertical, i.e. perpendicular to the substrate plane
• CPC Class Codes: H03H 2009/02519 Torsional
• CPC Class Codes: H03H 2009/02527 Combined
• CPC Class Codes: H03H 3/0078 involving adjustment of the transducing gap
• CPC Class Codes: H03H 9/02409 by application of a DC-bias voltage H03H9/02417 takes precedence
• CPC Class Codes: H03H 9/24 Constructional features of resonators of material which is not piezoelectric, electrostrictive, or magnetostrictive
• CPC Class Codes: H03H 9/2452 Free-free beam resonators
• CPC Class Codes: H03H 9/462 Microelectro-mechanical filters
• CPC Class Codes: H03H 9/465 in combination with other electronic elements
• CPC Class Codes: H03H 9/505 for microelectro-mechanical filters

Abstract

Several MEMS-based methods and architectures which utilize vibrating micromechanical resonators in circuits to implement filtering, mixing, frequency reference and amplifying functions are provided. Apparatus is provided for selecting at least one desired passband or channel in an RF transmitter subsystem utilizing a bank of vibrating micromechanical devices. One of the primary benefits of the use of such architectures is a savings in power consumption by trading power for high selectivity (i.e., high Q). Consequently, the present invention relies on the use of a large number of micromechanical links in SSI networks to implement signal processing functions with basically zero DC power consumption.

Claims

1. A method for filtering signals to obtain at least one desired passband of frequencies in a subsystem including a power amplifier to allow the power amplifier to operate with less power consumption, the method comprising:

providing a bank of micromechanical apparatus wherein each apparatus has at least one passband of frequencies and each of the apparatus is switchable and tunable;

controllably switching the bank of micromechanical apparatus to select the at least one desired passband and to substantially attenuate power outside the at least one desired passband; and

vibrating the micromechanical apparatus corresponding to the at least one desired passband.

2. The method as claimed in claim 1 wherein the subsystem is an RF transmitter subsystem and wherein the at least one desired passband is at least one desired channel.

3. The method as claimed in claim 1 wherein the apparatus are filters.

4. The method as claimed in claim 3 wherein each of the filters has a Q greater than 10.

5. The method as claimed in claim 4 wherein each of the filters has a Q greater than 1000.

6. The method as claimed in claim 5 wherein each of the filters has a Q greater than 5000.

7. The method as claimed in claim 3 wherein the bank of filters number over 10.

8. The method as claimed in claim 7 wherein the bank of filters number over 100.

9. The method as claimed in claim 8 wherein the number of filters number over 1000.

10. The method as claimed in claim 1 wherein the power amplifier is a non-linear or low power amplifier.

11. The method as claimed in claim 1 wherein the bank of micromechanical apparatus is a bank of micromechanical signal processors.

12. The method as claimed in claim 1 wherein the bank of micromechanical apparatus is a bank of micromechanical circuits.

13. An apparatus for processing signals in a transmit path, the apparatus comprising:

an amplifier that generates an amplified signal in the transmit path;

a bank of micromechanical bandpass filters coupled to the amplifier to receive the amplified signal; and

a controller for selecting at least one desired filter of the bank of filters;

wherein each of the filters includes an anchor and a vibrating filter structure anchored to a substrate via the anchor wherein the vibrating filter structure includes a vibrating beam.

14. An apparatus for processing signals in a transmit path, the apparatus comprising:

an amplifier that generates an amplified signal in the transmit path;

a bank of micromechanical bandpass filters coupled to the amplifier to receive the amplified signal; and

a controller for selecting at least one desired filter of the bank of filters;

wherein each of the filters includes an anchor and a vibrating filter structure anchored to a substrate via the anchor wherein each of the filters is switchable via application of a bias voltage to each filter.

15. In a subsystem including a power amplifier, a signal filtering apparatus for filtering signals to obtain at least one desired passband of frequencies while allowing the power amplifier to operate with less power consumption, the apparatus comprising:

a parallel bank of micromechanical filters wherein each of the filters has a passband and is capable of handling amplified signals and each of the filters is switchable and tunable; and

a controller for selecting at least one desired filter of the bank of filters to thereby provide the at least one desired passband of frequencies.

16. The apparatus as claimed in claim 15 wherein the subsystem is an RF transmitter subsystem and wherein the at least one desired passband is at least one desired channel.

17. The apparatus as claimed in claim 15 wherein each of the filters has an input connected to a common input and each of the filters has an output connected to a common output.

18. The apparatus as claimed in claim 15 wherein the controller includes a decoder for controlling application of an appropriate bias voltage to the at least one desired filter.

19. The apparatus as claimed in claim 15 wherein the apparatus is a high-Q, high-power filter.

20. A method for filtering signals to obtain at least one desired passband of frequencies in a subsystem including a power amplifier to allow the power amplifier to operate with less power consumption, the method comprising:

providing a bank of micromechanical filters wherein each filter has at least one passband of frequencies;

controllably switching the bank of micromechanical filters to select the at least one desired passband and to substantially attenuate power outside the at least one desired passband;

vibrating the micromechanical filter corresponding to the at least one desired passband; and

wherein each of the filters has a Q greater than 5000.

21. In a subsystem including a power amplifier, a signal filtering apparatus for filtering signals to obtain at least one desired passband of frequencies while allowing the power amplifier to operate with less power consumption, the apparatus comprising:

a parallel bank of micromechanical filters wherein each of the filters has a passband and is capable of handling amplified signals;

a controller for selecting at least one desired filter of the bank of filters to thereby provide the at least one desired passband of frequencies; and

wherein each of the filters has a Q greater than 5000.

22. In a subsystem including a power amplifier, a signal filtering apparatus for filtering signals to obtain at least one desired passband of frequencies while allowing the power amplifier to operate with less power consumption, the apparatus comprising:

a parallel bank of micromechanical filters wherein each of the filters has a passband and is capable of handling amplified signals;

a controller for selecting at least one desired filter of the bank of filters to thereby provide the at least one desired passband of frequencies; and

wherein the controller includes a decoder for controlling application of an appropriate bias voltage to the at least one desired filter.