Embodiments of resonator circuits and modulating resonators and are described generally herein. One or more acoustic wave resonators may be coupled in series or parallel to generate tunable filters. One or more acoustic wave resonances may be modulated by one or more capacitors or tunable capacitors. One or more acoustic wave modules may also be switchable in a filter. Other embodiments may be described and claimed.

A method of constructing an RF filter comprises designing an RF filter that includes a plurality of resonant elements disposed, a plurality of non-resonant elements coupling the resonant elements together to form a stop band having a plurality of transmission zeroes corresponding to respective frequencies of the resonant elements, and a sub-band between the transmission zeroes. The non-resonant elements comprise a variable non-resonant element for selectively introducing a reflection zero within the stop band to create a pass band in the sub-band. The method further comprises changing the order in which the resonant elements are disposed along the signal transmission path to create a plurality of filter solutions, computing a performance parameter for each of the filter solutions, comparing the performance parameters to each other, selecting one of the filter solutions based on the comparison of the computed performance parameters, and constructing the RF filter using the selected filter solution.

An acoustic structure is provided. The acoustic structure includes an acoustic resonator structure configured to resonate in a series resonance frequency (e.g., passband frequency) to pass a signal, or cause a series capacitance to block the signal in a parallel resonance frequency (e.g., stopband frequency). The parallel resonance frequency may become higher than the series resonance frequency when the tunable capacitance is lesser than or equal to two times of the series capacitance (C.sub.Tune≤2C.sub.0), or lower than the series resonance frequency when the tunable capacitance is greater than two times of the series capacitance (C.sub.Tune>2C.sub.0). In this regard, the acoustic structure can be configured to include a tunable reactive circuit to generate the tunable capacitance (C.sub.Tune) to adjust the parallel resonance frequency. As such, it may be possible to flexibly configure the acoustic resonator structure to block the signal in desired stopband frequencies.

Embodiments of resonator circuits and modulating resonators and are described generally herein. One or more acoustic wave resonators may be coupled in series or parallel to generate tunable filters. One or more acoustic wave resonances may be modulated by one or more capacitors or tunable capacitors. One or more acoustic wave modules may also be switchable in a filter. Other embodiments may be described and claimed.

A method for producing an adjustable bulk acoustic wave resonator comprising a transducer stack (E1) and a tuning stack (E2). According to the invention, transducer stack (E1) includes two defined electrodes (4, 6) and piezoelectric material (2), and stack (E2) includes a layer of piezoelectric material (8) and two defined electrodes (10, 12). The method includes: a) production of the transducer stack; b) formation of an electrically insulating layer on an electrode (6) of the transducer stack; c) formation of a defined electrode (10) of the tuning stack on the electrically insulting layer such that it is aligned with the electrodes of the transducer stack; d) assembly, on the electrode (10), of a substrate of piezoelectric material; e) fracturing of the substrate of piezoelectric material; and f) formation of the other defined electrode (12) of the tuning stack, aligned with the defined electrode (10).

A coupled resonator filter device is disclosed. The coupled resonator filter device includes a substrate with one or more acoustic reflector layers disposed over the substrate, a first lower electrode disposed over the one or more acoustic reflector layers, a first piezoelectric layer disposed over the first lower electrode, and a first upper electrode disposed over the first piezoelectric layer. The coupled resonator filter device further includes one or more acoustic coupling layers disposed over the first upper electrode, a second lower electrode disposed over the one or more acoustic coupling layers, a second piezoelectric layer disposed over the second lower electrode, a second upper electrode disposed over the second piezoelectric layer, and a first tuning capacitor having a first upper plate coupled to the first upper electrode and a first lower plate coupled to the first lower electrode.

Embodiments of resonator circuits and modulating resonators and are described generally herein. One or more acoustic wave resonators may be coupled in series or parallel to generate tunable filters. One or more acoustic wave resonances may be modulated by one or more capacitors or tunable capacitors. One or more acoustic wave modules may also be switchable in a filter. Other embodiments may be described and claimed.

A filter circuit is provided which allows the pass band to be tuned to a desired communication signal while achieving increased attenuation in a given frequency band that lies outside the pass band. A filter circuit includes a fixed filter and a tunable filter. The fixed filter has a pass band wider than a frequency band corresponding to a predetermined communication signal and overlapping with the frequency band corresponding to the communication signal. The tunable filter has a stop band narrower than the pass band of the fixed filter and having tunable frequency. The fixed filter and the tunable filter are connected in series.

In accordance with an embodiment, an RF system includes a transmit path having a first tunable transmit band stop filter, and a power amplifier coupled to an output of the first tunable transmit band stop filter, where the first tunable transmit band stop filter is configured reject a receive frequency and pass a transmit frequency; a receive path comprising an LNA; and a duplex filter having a transmit path port coupled to an output of the power amplifier, a receive path port coupled to an input of the LNA, and an antenna port, where the duplex filter is configured to pass the transmit frequency and reject the receive frequency between the antenna port and the transmit path port, pass the receive frequency and reject the transmit frequency between the antenna port and the receive path port.

An acoustic wave filter includes a substrate, a first resonator disposed on the substrate, a second resonator disposed on the substrate to be spaced apart from the first resonator, a connector electrically connecting the first and second resonators, and a variable capacitor formed in the connector to tune a pass band frequency of the acoustic wave filter.