# US 2013/0154754 A1 · Tuning of mems oscillator > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0154754 A1 - Document ID: US20130154754A1 - Status: Published application - Kind: A1 - Application number: 13/326,888 - Filed: 2011-12-15 - Published: 2013-06-20 - Earliest claimed: 2011-12-15 - Assignees: Avago Technologies Wireless IP (Singapore) Pte. Ltd. - Inventors: Michael FRANK - Web page: https://patentgrep.com/patent/US20130154754A1 ## CPC - H03B 5/364: {the amplifier comprising field effect transistors (H03B5/366 takes precedence)} - H03B 5/366: {and comprising means for varying the frequency by a variable voltage or current} - H03B 2200/0038: including a current mirror - H03B 2200/005: including measures to switch a capacitor - H03B: GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS (generators adapted for electrophonic musical instruments G10H; masers or lasers H01S; generation of oscillations in plasma H05H) ## Abstract A method is provided for tuning a microelectromechanical systems (MEMS) oscillator comprising an acoustic resonator and a tuning and amplification circuit arranged in a loop. The method comprises determining an initial oscillation frequency of the oscillator, modifying a capacitance of the tuning and amplification circuit according to the initial oscillation frequency, and adjusting a power level of the oscillator according to the modified capacitance. ## Claims ### Claim 1 A method of tuning a microelectromechanical systems (MEMS) oscillator comprising an acoustic resonator and a tuning and amplification circuit arranged in a loop, the method comprising: determining an oscillation frequency of the oscillator; modifying a capacitance of the tuning and amplification circuit according to the oscillation frequency; and adjusting a power level of the oscillator according to the modified capacitance. ### Claim 2 (depends on 1) The method of claim 1, wherein the tuning and amplification circuit comprises a field effect transistor (FET) biased to a linear region, and adjusting the power level of the oscillator comprises adjusting a gate to source voltage of the FET. ### Claim 3 (depends on 1) The method of claim 1, wherein the tuning and amplification circuit comprises a bipolar junction transistor (BJT) biased to a linear region, and adjusting the power level of the oscillator comprises adjusting a base current of the BJT. ### Claim 4 (depends on 1) The method of claim 1, further comprising: determining whether the oscillation frequency has reached a target frequency; and upon determining that the oscillation frequency has not reached the target frequency, iteratively repeating the modifying and adjusting. ### Claim 5 (depends on 1) The method of claim 1, wherein the acoustic resonator comprises a film bulk acoustic resonator (FBAR) and the tuning and amplification circuit comprises a transistor, at least one fixed capacitor, and at least one variable capacitor. ### Claim 6 (depends on 5) The method of claim 5, wherein the at least one variable capacitor comprises a switched capacitor, and modifying the capacitance of the tuning and amplification circuit comprises closing a switch of the switched capacitor. ### Claim 7 (depends on 1) The method of claim 1, wherein modifying the capacitance of the tuning and amplification circuit according to the initial oscillation frequency comprises: (a) incrementing the capacitance by a predetermined amount; (b) determining a difference between the oscillation frequency and a target frequency; and (c) upon determining that the difference is sufficiently large, repeating (a) and (b) until the difference is determined to be lower than a predetermined amount. ### Claim 8 (depends on 7) The method of claim 7, further comprising adjusting the power level of the oscillator by a predetermined amount each time the capacitance is incremented. ### Claim 9 A microelectromechanical systems (MEMS) oscillator, comprising; an acoustic resonator; a tuning and amplification circuit connected with the resonator in a loop and having an adjustable gain and capacitance, wherein the tuning and amplification circuit is configured to tune the oscillator to a target frequency by modifying the adjustable gain and capacitance; and an adjustable power source connected to the loop and configured to adjust an amount of power supplied to the loop according to the capacitance of the tuning and amplification circuit. ### Claim 10 (depends on 9) The MEMS oscillator of claim 9, wherein the adjustable power source is an adjustable current source. ### Claim 11 (depends on 9) The MEMS oscillator of claim 9, wherein the tuning and amplification circuit comprises: a transistor having a first terminal connected to one side of the loop, a second terminal connected to another side of the loop, and a third terminal connected to a reference voltage; and at least one variable capacitor connected to the first terminal or the second terminal. ### Claim 12 (depends on 11) The MEMS oscillator of claim 11, wherein the transistor is a field effect transistor (FET), the first terminal is a gate terminal, the second terminal is a drain terminal, and the third terminal is a source terminal, and wherein the adjustable power source adjusts the amount of power supplied to the loop to increase a gate to source voltage of the FET to compensate for an increased capacitance of the tuning and amplification circuit. ### Claim 13 (depends on 9) The MEMS oscillator of claim 9, wherein the tuning and amplification circuit comprises: a field effect transistor (FET) having a source connected to a reference voltage; a first fixed capacitor connected between a gate of the FET and the reference voltage; a first variable capacitor connected between the gate of the FET and the reference voltage; a second fixed capacitor connected between a drain of the FET and the reference voltage; a second variable connected between the drain of the FET and the reference voltage; and a resistor connected in parallel with the resonator. ### Claim 14 (depends on 13) The MEMS oscillator of claim 13, wherein the adjustable power source comprises a current source, and the MEMS oscillator further comprises a resistor located between the current source and the loop. ### Claim 15 (depends on 9) The MEMS oscillator of claim 9, wherein the tuning and amplification circuit comprises at least one switched capacitor configured to adjust the capacitance. ### Claim 16 (depends on 9) The MEMS oscillator of claim 9, wherein the resonator is a film bulk acoustic resonator (FBAR). ### Claim 17 (depends on 9) The MEMS oscillator of claim 9, wherein the tuning and amplification circuit comprises at least one varactor configured to adjust the capacitance. ### Claim 18 A method of tuning an oscillator comprising an acoustic resonator and a tuning and amplification circuit connected in a loop, wherein the tuning and amplification circuit comprises a transistor and a plurality of tuning capacitors, the method comprising: increasing a capacitance of the tuning capacitors in combination with a gate to source voltage of the transistor. ### Claim 19 (depends on 18) The method of claim 18, wherein increasing the gate to source voltage of the transistor comprises increasing a current applied to the loop. ### Claim 20 (depends on 18) The method of claim 18, wherein increasing the tuning capacitance comprises determining an initial oscillating frequency of the oscillator, and increasing the tuning capacitance in proportion to a difference between the initial oscillating frequency and a target oscillating frequency.