A system includes a local oscillator (LO) signal generation circuit, a receiver (RX) circuit, and a calibration circuit. The LO signal generation circuit generates an LO signal according to a reference clock, and includes an active oscillator that generates the reference clock. The active oscillator includes at least one active component. The RX circuit generates a processed RX signal by processing an RX input signal according to the LO signal. The calibration circuit checks a signal characteristic of the processed RX signal by detecting if a calibration tone exists within a receiver bandwidth, set a frequency calibration control output in response to the calibration tone being not found in the receiver bandwidth, and output the frequency calibration control output to the LO signal generation circuit. The LO signal generation circuit adjusts an LO frequency of the LO signal in response to the frequency calibration control output.

A system includes a local oscillator (LO) signal generation circuit, a receiver (RX) circuit, and a calibration circuit. The LO signal generation circuit generates an LO signal according to a reference clock, and includes an active oscillator that generates the reference clock. The active oscillator includes at least one active component. The RX circuit generates a processed RX signal by processing an RX input signal according to the LO signal. The calibration circuit checks a signal characteristic of the processed RX signal by detecting if a calibration tone exists within a receiver bandwidth, set a frequency calibration control output in response to the calibration tone being not found in the receiver bandwidth, and output the frequency calibration control output to the LO signal generation circuit. The LO signal generation circuit adjusts an LO frequency of the LO signal in response to the frequency calibration control output.

An oscillator comprising a first oscillator circuit having a first inductive portion, a plurality of shared switches for selectively connecting a shared oscillator tuning circuit and a second oscillator circuit having a second inductive portion, the plurality of shared switches and the shared oscillator tuning circuit. In some embodiments, when the first oscillator circuit is active, the second oscillator circuit is inactive to allow the sharing of the shared oscillator tuning circuit.

An oscillator comprising a first oscillator circuit having a first inductive portion, a plurality of shared switches for selectively connecting a shared oscillator tuning circuit and a second oscillator circuit having a second inductive portion, the plurality of shared switches and the shared oscillator tuning circuit. In some embodiments, when the first oscillator circuit is active, the second oscillator circuit is inactive to allow the sharing of the shared oscillator tuning circuit.

A pet monitoring device (101) for monitoring a sub-dermal RFID microchip (103), the pet monitoring device comprising: a wearable item (1) bearing 1 to 5 turns of electrical conductor (7) wound circumferentially to form a wearable item resonator; and an RFID reader (9) attachable and detachable to said wearable item, wherein said RFID reader comprises: a driving circuit (1100) comprising a primary inductance (Lp) inductively coupled to said wearable item when said RFID reader is attached to said wearable item; a secondary inductance (Ls) and resonance capacitor (Cs) conductively coupled to said wearable item when said RFID reader is attached to said wearable item, wherein the secondary inductance and resonance capacitor form the wearable item resonator with said electrical conductor, wherein the wearable item resonator comprises a circuit (1004) to automatically adjust said resonance capacitor to compensate for a size of said wearable item when fitted to said pet; wherein the driving circuit is operable to drive the wearable item resonator.

A pet monitoring device (101) for monitoring a sub-dermal RFID microchip (103), the pet monitoring device comprising: a wearable item (1) bearing 1 to 5 turns of electrical conductor (7) wound circumferentially to form a wearable item resonator; and an RFID reader (9) attachable and detachable to said wearable item, wherein said RFID reader comprises: a driving circuit (1100) comprising a primary inductance (Lp) inductively coupled to said wearable item when said RFID reader is attached to said wearable item; a secondary inductance (Ls) and resonance capacitor (Cs) conductively coupled to said wearable item when said RFID reader is attached to said wearable item, wherein the secondary inductance and resonance capacitor form the wearable item resonator with said electrical conductor, wherein the wearable item resonator comprises a circuit (1004) to automatically adjust said resonance capacitor to compensate for a size of said wearable item when fitted to said pet; wherein the driving circuit is operable to drive the wearable item resonator.

An RFID reader, tuning method and computer readable medium. A carrier signal is transmitted. A plurality of feedback signals produced in the RFID reader are measured when transmitting the carrier signal with a variable matching network set at a plurality of impedance values that are different from one another. It is determined which impedance value of the plurality of impedance values produced a feedback signal having a highest level of the plurality of feedback signals. The variable matching network is set to the determined impedance value.

An RFID reader, tuning method and computer readable medium. A carrier signal is transmitted. A plurality of feedback signals produced in the RFID reader are measured when transmitting the carrier signal with a variable matching network set at a plurality of impedance values that are different from one another. It is determined which impedance value of the plurality of impedance values produced a feedback signal having a highest level of the plurality of feedback signals. The variable matching network is set to the determined impedance value.

A wireless system includes a local oscillator (LO) signal generation circuit, a receiver (RX) circuit, and a calibration circuit. The LO signal generation circuit generates an LO signal according to a reference clock. The LO signal generation circuit includes an active oscillator. The active oscillator generates the reference clock, wherein the active oscillator includes at least one active component, and does not include an electromechanical resonator. The RX circuit generates a down-converted RX signal by performing down-conversion upon an RX input signal according to the LO signal. The calibration circuit generates a frequency calibration control output according to a signal characteristic of the down-converted RX signal, and outputs the frequency calibration control output to the LO signal generation circuit. The LO signal generation circuit adjusts an LO frequency of the LO signal in response to the frequency calibration control output.

A wireless system includes a local oscillator (LO) signal generation circuit, a receiver (RX) circuit, and a calibration circuit. The LO signal generation circuit generates an LO signal according to a reference clock. The LO signal generation circuit includes an active oscillator. The active oscillator generates the reference clock, wherein the active oscillator includes at least one active component, and does not include an electromechanical resonator. The RX circuit generates a down-converted RX signal by performing down-conversion upon an RX input signal according to the LO signal. The calibration circuit generates a frequency calibration control output according to a signal characteristic of the down-converted RX signal, and outputs the frequency calibration control output to the LO signal generation circuit. The LO signal generation circuit adjusts an LO frequency of the LO signal in response to the frequency calibration control output.