There is provided a semiconductor device including an oscillation circuit that includes a plurality of capacitors provided on a semiconductor substrate, a conversion circuit that converts an analog signal into a digital signal, and a switch circuit that switches the capacitors on the basis of the digital signal. Further, an oscillation frequency linearly varies with respect to a variation in the analog signal.

A circuit device includes an oscillation circuit and a processing circuit. The oscillation circuit includes a variable capacitance circuit configured by a capacitor array and oscillates at an oscillation frequency corresponding to the capacitance value of the variable capacitance circuit. First temperature data and second temperature data subsequent to the first temperature data are input to the processing circuit as temperature data. In the period between the start of the capacitance control based on the first temperature data and the start of the capacitance control based on the second temperature data, the processing circuit switches the first capacitance control data corresponding to the first temperature data and the second capacitance control data different from the first capacitance control data in a time-division manner to be output to the variable capacitance circuit.

A method includes transmitting, by a radio frequency identification (RFID) reader, a series of RF signals to a plurality of RF receiver circuits in a time sequence. The first RF signal commands the plurality of RF receiver circuits to remain silent when received signal strength of the first RF signal corresponds to a power level greater than a first power level. The method further includes receiving one or more sets of responses from one or more sets of RF receiver circuits of the plurality of RF receiver circuits in response to the series of RF signals. The method further includes determining an area of interest based on the one or more sets of responses, determining a set of power levels corresponding to the area of interest, and transmitting a second series of RF signals to the plurality of RF receiver circuits in a second time sequence.

Methods and apparatuses for use in tuning reactance are described. Open loop and closed loop control for tuning of reactances are also described. Tunable inductors and/or tunable capacitors may be used in filters, resonant circuits, matching networks, and phase shifters. Ability to control inductance and/or capacitance in a circuit leads to flexibility in operation of the circuit, since the circuit may be tuned to operate under a range of different operating 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 radio frequency identification (RFID) tag includes an antenna operable to receive a radio frequency (RF) signal having a carrier frequency. The RFID tag further includes a tank circuit coupled to the antenna. The RFID tag further includes a tuning circuit operable to determine a received power level of the RF signal at the carrier frequency, determine whether the received power level is lower than a power level threshold. When the received power level is lower than the power level threshold: tuning circuit increases the input impedance of the RFID tag, determines a most recent power level of the received RF signal, and compares the most recent power level with the received power level. When the most recent power level is greater than the received power level, the tuning circuit incrementally increases the input impedance until the received power level is substantially equal to the power level threshold.

A power detector for use in an RF receiver. The detector includes a power reference generator and a power quantizer. The power reference generator develops a power reference current, voltage, or signal as a function of a power transferred via a received RF signal. The power quantizer is responsive to the power reference current, voltage, or signal to develop a digital field power value indicative of the power reference current, voltage, or signal.

In a first clock frequency multiplier, multiple injection-locked oscillators (ILOs) having spectrally-staggered lock ranges are operated in parallel to effect a collective input frequency range substantially wider than that of a solitary ILO. After each input frequency change, the ILO output clocks may be evaluated according to one or more qualifying criteria to select one of the ILOs as the final clock source. In a second clock frequency multiplier, a flexible-injection-rate injection-locked oscillator locks to super-harmonic, sub-harmonic or at-frequency injection pulses, seamlessly transitioning between the different injection pulse rates to enable a broad input frequency range. The frequency multiplication factor effected by the first and/or second clock frequency multipliers in response to an input clock is determined on the fly and then compared with a programmed (desired) multiplication factor to select between different frequency-divided instances of the frequency-multiplied clock.

A method includes sending, by a reader, a radio frequency (RF) signal to a wireless sensor that includes an antenna having a tail section and a head section. The tail section is for placement in an RF limited area for sensing moisture in a first location of a vehicle under test and wherein the head section is for placement in a non-RF limited area. The method further includes receiving, by the reader, an RF response to the RF signal from the wireless sensor. The first RF response includes an indication of adjustment of one or more RF characteristics of the wireless sensor, which corresponds to a variance of the one or more RF characteristics from a desired value, which, in turn, corresponds to a level of moisture at the first location. The method further includes outputting, by the reader, a message regarding the level of moisture at the first location.

Signal generation devices including an auto-tuning electronic circuit module for generating tuned output signals are disclosed. The auto-tuning electronic circuit module may include a tunable resonant electronic circuit element for providing a tuned output signal, including a voltage divider element and a tuning array element and control element.