Oscillator having a plurality of switchable MEMS vibrators

• US 8,669,824 B2
• Filed: 03/16/2012
• Issued: 03/11/2014
• Est. Priority Date: 03/17/2011
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Yajima, Aritsugu
• Primary Examiner(s): Gannon, Levi
• Application Number:
  US13/422,323
• Publication Number:
  US 20120235760A1
• Time in Patent Office: 725 Days
• Field of Search: 310/342, 327/298, 331/46, 331/49, 331/56, 331/116.FE, 331/116.M, 331/116.R, 331/154, 331/158, 331/162, 331/179, 333/189, 333197-199
• US Class Current: 331/162
• CPC Class Codes: H03B 2200/0012 Pierce oscillator
• CPC Class Codes: H03B 2200/0052 including measures to switch the feedback circuit
• CPC Class Codes: H03B 5/30 with frequency-determining element being electromechanical resonator

Abstract

An oscillation circuit includes a plurality of MEMS vibrators each having a first terminal and a second terminal, and having respective resonant frequencies different from each other, an amplifier circuit (an inverting amplifier circuit) having an input terminal and an output terminal, and a connection circuit adapted to connect the first terminal of one of the MEMS vibrators and the input terminal to each other, and the second terminal of the MEMS vibrator and the output terminal to each other to thereby connect the one of the MEMS vibrators and the amplifier circuit (the inverting amplifier circuit) to each other.

Claims

1. An oscillation circuit comprising:

a plurality of MEMS vibrators each having a first terminal and a second terminal, and having respective resonant frequencies different from each other;

an amplifier circuit having an input terminal and an output terminal; and

a connection circuit adapted to connect the first terminal of one of the MEMS vibrators and the input terminal to each other, and the second terminal of the one of the MEMS vibrator and the output terminal to each other to thereby connect the one of the MEMS vibrators and the amplifier circuit to each other, wherein

the connection circuit connects the first terminal and the second terminal of the MEMS vibrator, which fails to be connected to the amplifier circuit, to a first reference potential.

2. The oscillation circuit according to claim 1, wherein

the connection circuit includes at least one of

a first switch adapted to switch a connection state between the first terminal of each of the MEMS vibrators and the input terminal, and

a second switch adapted to switch a connection state between the second terminal of each of the MEMS vibrators and the output terminal.

3. The oscillation circuit according to claim 2, wherein

the connection circuit includes

the first switch, and

the second switch.

4. The oscillation circuit according to claim 1, wherein

the connection circuit includes

a third switch adapted to switch a connection state between the first terminal of the MEMS vibrator, which fails to be connected to the amplifier circuit, and the first reference potential, and

a fourth switch adapted to switch a connection state between the second terminal of the MEMS vibrator, which fails to be connected to the amplifier circuit, and the first reference potential.

5. The oscillation circuit according to claim 1, further comprising:

a first capacitor connected between the input terminal and a second reference potential; and

a second capacitor connected between the output terminal and the second reference potential.

6. An oscillation circuit comprising:

a plurality of MEMS structures each having a first terminal and a second terminal, and having respective resonant frequencies in a resonant state different from each other; and

an amplifier circuit having an input terminal and an output terminal,

wherein the first terminal of one of the MEMS structures and the input terminal are connected to each other,

the second terminal of the one of the MEMS structures and the output terminal are connected to each other,

the first terminal of the other of the MEMS structures and the input terminal fail to be connected to each other,

the second terminal of the other of the MEMS structures and the output terminal fail to be connected to each other, and

the first terminal of the other of the MEMS structures and the second terminal of the other of the MEMS structures are connected to a first reference potential.

7. The oscillation circuit according to claim 6, further comprising:

a first capacitor connected between the input terminal and a second reference potential; and

a second capacitor connected between the output terminal and the second reference potential.

8. The oscillation circuit according to claim 6, wherein

the input terminal is a terminal having a function of inputting a signal to the amplifier circuit, and

the output terminal is a terminal having a function of outputting a signal amplified by the amplifier circuit.

9. The oscillation circuit according to claim 6, wherein

the first terminal is a terminal having a function of outputting a signal generated due to a resonance of the MEMS structure, and

the second terminal is a terminal having a function of feeding back the signal amplified by the amplifier circuit to the MEMS structure.