An on-chip balun comprising a primary side, a secondary side, and an integrated notch filter.

A non-volatile adjustable phase shifter is coupled to a transceiver in a wireless communication device. The non-volatile adjustable phase shifter includes a non-volatile radio frequency (RF) switch. In one implementation, the non-volatile RF switch is a phase-change material (PCM) RF switch. In one approach, the non-volatile adjustable phase shifter includes a selectable transmission delay arm and a selectable transmission reference arm. A phase shift caused by the non-volatile adjustable phase shifter is adjusted when the non-volatile RF switch engages with or disengages from the selectable transmission delay arm. In another approach, the non-volatile adjustable phase shifter includes a selectable impedance element. A phase shift caused by the non-volatile adjustable phase shifter is adjusted when the non-volatile RF switch engages with or disengages from the selectable impedance element. In either approach, the phase shift changes a phase of RF signals being transmitted from or received by the transceiver.

A battery emulator can include an active voltage controlled device (VCD), one or more selectable RC filter banks, and a controller coupled to the active VCD and the one or more selectable RC filter banks. The controller may be configured to sense a load on the battery emulator and control the active VCD so as to implement a low frequency battery transfer function derived from a battery model. The controller may be further configured to control the one or more selectable RC filter banks so as to implement a high frequency battery transfer function derived from the battery model. The controller may further include a gas gauge emulation module configured to interface with a gas gauge interface of a device under test. The controller may further include a communications module configured to interface with a test host.

Methods and system for using a multifunctional filter to minimize insertion loss in a multi-mode communications system are described. Specifically described is a multifunctional filter that is configurable to operate in a band-pass mode when a first type of signal is propagated through the multifunctional filter, and to operate in a low-pass mode when a second type of signal is propagated through the multifunctional filter. The multifunctional filter presents a lower insertion loss to the second type of signal when operating in the low-pass mode than in the band-pass mode.

An on-chip balun comprising a primary side, a secondary side, and an integrated notch filter.

An acoustic wave filter device includes a ground connection terminal connected to an external ground electrode, a serial arm resonator, a first parallel arm circuit connected to a first node of the serial arm resonator, the first node being positioned closer to an input/output terminal, and to the ground connection terminal, and a second parallel arm circuit connected to a second node of the serial arm resonator, the second node being positioned closer to an input/output terminal, and to the ground connection terminal. The first parallel arm circuit includes a parallel arm resonator having a resonant frequency higher than a center frequency of a filter pass band, and a frequency varying circuit connected to the parallel arm resonator and the ground connection terminal. The second parallel arm circuit includes a parallel arm resonator having a resonant frequency higher than the center frequency of the filter pass band.

A radio-frequency filter includes a first series-arm circuit and a second series-arm circuit that is on a circuit path closer to the output terminal than the first series-arm circuit. A first parallel-arm circuit is connected to a ground and a node on the path between the first series-arm circuit and the second series-arm circuit. The first series-arm circuit includes a first series-arm resonator, and a first switch element, the first switch element including first semiconductor elements arranged in series. The second series-arm circuit includes a second series-arm resonator, and a second switch element, the second switch element including at least one second semiconductor element. A first stack number being higher than a second stack number, the first stack number being a number of the first semiconductor elements and the second stack number being a number of the one or more second semiconductor elements.

A flexible multi-path RF adaptive tuning network switch architecture that counteracts impedance mismatch conditions arising from various combinations of coupled RF band filters, particularly in a Carrier Aggregation-based (CA) radio system. In one version, a digitally-controlled tunable matching network is coupled to a multi-path RF switch in order to provide adaptive impedance matching for various combinations of RF band filters. Optionally, some or all RF band filters include an associated digitally-controlled filter pre-match network to further improve impedance matching. In a second version, some or all RF band filters coupled to a multi-path RF switch include a digitally-controlled phase matching network to provide necessary per-band impedance matching. Optionally, a digitally-controlled tunable matching network may be included on the common port of the multi-path RF switch to provide additional impedance matching capability. In a third version, CA direct mapped adaptive tuning networks include filter tuning blocks for selected lower frequency bands.

A capacitance adjustment method for enabling or disabling a first set of capacitors to an n.sub.th set of capacitors of n sets of capacitors, includes generating a base count according to base capacitance, generating a first count to an n.sub.th count according to the first set of capacitors to the n.sub.th set of capacitors respectively, obtaining a first ratio to an n.sub.th ratio according to the base count and the first count to the n.sub.th count, indicating a target count, obtaining a target ratio according to the base count and the target count, and obtaining a first control signal to an n.sub.th control signal according to the target ratio and the first ratio to the n.sub.th ratio so as to enable or disable the first set of capacitors to the n.sub.th set of capacitors accordingly.

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.