Embodiments of the present disclosure include a microcontroller with a frequency test circuit, a device-under-test (DUT) input, and a calculation engine circuit. The calculation engine circuit is configured to compare a measured frequency from the frequency test circuit measured from the DUT input to a reference frequency stored in memory, and, based on the comparison, adjust frequency of the DUT generating the DUT input.

Devices and methods for tuning a tunable circuit based on a frequency of operation of the tunable circuit using a clockless frequency detector circuit are described. The clockless frequency detector uses a filter having a slope in its frequency response curve that includes a frequency range of operation of the tunable circuit. Frequency-based attenuation through the filter of an RF signal provided to the tunable circuit is used to provide an indication of the frequency of operation. The tunable circuit, including the clockless frequency detector, can be integrated within a same chip that is autonomously configurable based on the frequency of operation.

An electronic device may be provided with wireless circuitry and control circuitry. The wireless circuitry may include an antenna with an inverted-F antenna resonating element formed from portions of a peripheral conductive electronic device housing structure and may have an antenna ground that is separated from the antenna resonating element by a gap. The antenna may include a first adjustable component coupled between the antenna resonating element arm and the antenna ground on a first side of the antenna feed and a second adjustable component coupled between the antenna resonating element arm and the antenna ground on a second side of the antenna feed. Control circuitry in the electronic device may adjust the first and second adjustable components between a first tuning mode, a second tuning mode, and a third tuning mode.

An electronic device may be provided with wireless circuitry and control circuitry. The wireless circuitry may include an antenna with an inverted-F antenna resonating element formed from portions of a peripheral conductive electronic device housing structure and may have an antenna ground that is separated from the antenna resonating element by a gap. The antenna may include a first adjustable component coupled between the antenna resonating element arm and the antenna ground on a first side of the antenna feed and a second adjustable component coupled between the antenna resonating element arm and the antenna ground on a second side of the antenna feed. Control circuitry in the electronic device may adjust the first and second adjustable components between a first tuning mode, a second tuning mode, and a third tuning mode.

Devices and methods for tuning a tunable circuit based on a frequency of operation of the tunable circuit using a clockless frequency detector circuit are described. The clockless frequency detector uses a filter having a slope in its frequency response curve that includes a frequency range of operation of the tunable circuit. Frequency-based attenuation through the filter of an RF signal provided to the tunable circuit is used to provide an indication of the frequency of operation. The tunable circuit, including the clockless frequency detector, can be integrated within a same chip that is autonomously configurable based on the frequency of operation.

Embodiments of the present disclosure include a microcontroller with a frequency test circuit, a device-under-test (DUT) input, and a calculation engine circuit. The calculation engine circuit is configured to compare a measured frequency from the frequency test circuit measured from the DUT input to a reference frequency stored in memory, and, based on the comparison, adjust frequency of the DUT generating the DUT input.

An electronic atomization device includes: a heating element for atomizing an aerosol-forming material: an electromagnetic heating circuit with an inverse class-E characteristic; a power supply circuit connected to the electromagnetic heating circuit so as to supply power to the electromagnetic heating circuit; and a drive circuit connected to the electromagnetic heating circuit so as to generate a drive signal. The electromagnetic heating circuit controls, based on a change of the drive signal, the heating element to atomize the aerosol-forming material.

A wrist-worn electronic device comprises a housing, a first antenna, a second antenna, and an electrical switch. The housing includes a circumferential side wall, an electrically conductive bezel, a bezel retainer, a lower ring and an electrically conductive bottom plate. The first antenna is formed in part by a portion of the bezel and receives a first wireless signal having a first frequency in a global navigation satellite system (GNSS) band. The second antenna is formed in part by at least a portion of the bottom plate and transmits a second wireless signal to a non-terrestrial network (NTN), receives a third wireless signal from the NTN, or both. The electrical switch having a plurality of selectable positions each associated with a tuning network that causes the second antenna to transmit the second wireless signal at a second frequency and to receive the third wireless signal at a third frequency.