A filter and an operating method thereof are provided. The filter includes a logic circuit, a power circuit and a filter circuit. The logic circuit provides a switching control signal. The power circuit is coupled to the logic circuit. The filter circuit is coupled to the power circuit and the logic circuit. The filter circuit includes an amplifier, a first capacitor and a first transistor. An output end of the amplifier is coupled to the logic circuit, and provides an output signal. The first capacitor is coupled between an input end and output end of the amplifier. The first transistor is connected in parallel with the first capacitor. A control end of the first transistor is coupled to the power circuit. The logic circuit provides a switching control signal to the power circuit according to the output signal. The power circuit supplies a control voltage to the first transistor according to the switching control signal. Therefore, the filter of the present invention and its method of operation can provide an accurate filtered signal output function.

A filter and an operating method thereof are provided. The filter includes a logic circuit, a power circuit and a filter circuit. The logic circuit provides a switching control signal. The power circuit is coupled to the logic circuit. The filter circuit is coupled to the power circuit and the logic circuit. The filter circuit includes an amplifier, a first capacitor and a first transistor. An output end of the amplifier is coupled to the logic circuit, and provides an output signal. The first capacitor is coupled between an input end and output end of the amplifier. The first transistor is connected in parallel with the first capacitor. A control end of the first transistor is coupled to the power circuit. The logic circuit provides a switching control signal to the power circuit according to the output signal. The power circuit supplies a control voltage to the first transistor according to the switching control signal. Therefore, the filter of the present invention and its method of operation can provide an accurate filtered signal output function.

A near field radio-frequency identification (RFID) probe includes a probe tip comprising a resonant coil configured to communicate with an RFID compatible device at a predetermined resonant frequency. The near field RFID probe further includes a plurality of switch capacitor networks each comprising a capacitor and an RF switch, wherein switching the plurality of switch capacitor networks changes the capacitance of the resonant coil, thereby changing the resonant frequency of the resonant coil. The near field RFID probe further includes a probe control module configured to adjust the resonant frequency of the resonant coil to maintain the predetermined resonant frequency by switching the switch capacitor networks responsive to detecting that the resonant frequency of the resonant coil has deviated from the predetermined resonant frequency.

A switched-capacitor converter includes a rectifier at the output, a plurality of legs coupled between the input and the rectifier, and a controller. Each leg of the switched-capacitor converter includes a capacitor, and a switch device is connected to each leg. A first group of the legs is coupled to a first branch of the rectifier, and a second group of the legs is coupled to a second branch of the rectifier. The controller alternates switching of the first and second groups of legs after startup, to transfer energy from the input to the output during a first part of each switching cycle via the first group of legs and to ground during a second part of each switching cycle via the second group of legs. The controller or a current limited source provides for pre-charging of at least one of the capacitors during startup.

A microelectromechanical resonant circulator device is providing, having a substrate, and at least three electrical ports supported on the substrate. At least three electromechanical resonator elements are connected with associated switch elements and an associated port. The switch elements are operative to provide commutation over time of the electromechanical resonator elements.

A frequency synthesizer, comprises a phase frequency detector to receive a frequency signal and a reference clock, and to output a phase difference according to a phase difference and a frequency difference between the frequency signal and the reference clock; a charge pump to generate a current according to the phase difference; a loop filter to generate a first voltage signal based on the current; a N-path filter each comprising a switch, a path filter and to generate N paths of filtered voltages based on the first voltage; a voltage control oscillator to generate a second voltage signal based on a sum of the N paths of filtered voltages; a frequency divider to generate the frequency signal based on the second voltage signal and a variable frequency dividing ratio; and a Sigma-Delta Modulator to generate the variable frequency dividing ratio based on a digital representation of a frequency fractional value and the reference clock.

A low noise amplifier is provided. The low noise amplifier includes an input port, an output port, an inverter, a plurality of switched-capacitor units and a feedback inductor. The inverter is electrically connected between the input port and the output port. Each of the plural switched-capacitor units is electrically connected with the inverter in parallel and includes a switch and a capacitor connected in series. The feedback inductor is electrically connected with the inverter in parallel.

A tunable filter is described where the frequency response as well as bandwidth and transmission loss characteristics can be dynamically altered, providing improved performance for transceiver front-end tuning applications. The rate of roll-off of the frequency response can be adjusted to improve performance when used in duplexer applications. The tunable filter topology is applicable for both transmit and receive circuits. A method is described where the filter characteristics are adjusted to account for and compensate for the frequency response of the antenna used in a communication system.

A stacked switched resistance device has been developed. The stacked switched resistance device includes a plurality of segments connected in series. Each segment includes a resistor including an inherent parasitic capacitance, and a switch connected in series with the resistor, the switch being configured to connect and disconnect the resistor from the plurality of segments in response to a predetermined clock signal. An effective resistance of the stacked switched resistance device exceeds another effective resistance of at least one resistor with an equivalent inherent resistance that is connected in series to a single switch configured to connect and disconnect the at least one resistor in response to the predetermined clock signal.

A near field radio-frequency identification (RFID) probe includes a probe tip comprising a resonant coil configured to communicate with an RFID compatible device at a predetermined resonant frequency. The near field RFID probe further includes a plurality of switch capacitor networks each comprising a capacitor and an RF switch, wherein switching the plurality of switch capacitor networks changes the capacitance of the resonant coil, thereby changing the resonant frequency of the resonant coil. The near field RFID probe further includes a probe control module configured to adjust the resonant frequency of the resonant coil to maintain the predetermined resonant frequency by switching the switch capacitor networks responsive to detecting that the resonant frequency of the resonant coil has deviated from the predetermined resonant frequency.