Performance indicator circuitry is provided for characterizing performance of a phase locked loop (PLL) in a phase path of a polar modulator or polar transmitter that is used to generate a phase modulated RF signal. The PLL includes an oscillator, a high pass path, and a low pass path. The low pass path includes a loop filter. The performance indicator circuitry includes first input circuitry and parameter calculation circuitry. The first input circuitry is configured to input a loop filter signal from the loop filter. The parameter calculation circuitry is configured to compute a value for a performance indicator based on the loop filter signal and control or characterize an aspect of operation of the PLL based on the value.

Embodiments of oscillator circuits for wireless transmission of data are disclosed herein. In one example, an oscillator circuit includes an active network and a passive differential network coupled to the active network is disclosed. The active network is configured to generate an active signal for sustaining oscillation of the oscillator circuit. The passive network includes a first subnetwork, a second subnetwork, a first inductor and a second inductor. The first subnetwork is configured to adjust a central value of a resonant frequency of the oscillation. The passive network further includes a second subnetwork configured to further adjust the resonant frequency of the oscillation.

A sensor interface circuit includes: an RF switch having a control node; a bias circuit electrically connected to the control node and applying, to the control node, a voltage at a first level or a second level corresponding to a linear region of a reflection characteristic; a first variable oscillation circuit electrically connectable to a first sensor; a second variable oscillation circuit electrically connectable to a second sensor; and a difference circuit electrically connected between the first variable oscillation circuit and the bias circuit, and between the second variable oscillation circuit and the bias circuit.

A double frequency-shift keying modulating device includes a modulation module. The modulation module receives an oscillating signal and a digital signal, and generates a modulation output signal that has a first frequency. The first frequency is associated with a frequency of the oscillating signal and varies periodically at a second frequency. The second frequency is associated with the digital signal and the frequency of the oscillating signal.

A double frequency-shift keying modulating device includes a modulation module. The modulation module receives an oscillating signal and a digital signal, and generates a modulation output signal that has a first frequency. The first frequency is associated with a frequency of the oscillating signal and varies periodically at a second frequency. The second frequency is associated with the digital signal and the frequency of the oscillating signal.