Various methods provide for trimming the gain in a dual-port phase-locked loop (PLL) of a radio transceiver. Use is made of the radio's demodulator to perform modulation accuracy measurements, thereby reducing the cost and complexity of external test equipment.

A time to digital converter may include a synchronization block configured to output a voltage pulse with duration based on a time difference between a reference oscillating signal and an input oscillating signal; a charge pump arranged to receive the voltage pulse and to convert the voltage pulse into a current pulse; an integrator comprising an integrator capacitor, the integrator being configured to receive the current pulse and integrate the current pulse as a charge on the integrator capacitor, resulting in an integrator output voltage; and a successive approximation register configured to determine the integrator output voltage with respect to a reference voltage by adjusting the charge on the integrator capacitor so as to reduce the integrator output voltage to within a least significant bit (D0) of a reference voltage by successive approximation, and configured to output the determined integrator output voltage as a digital signal.

An apparatus is described that, according to an exemplary embodiment, has an RF oscillator for generating an RF oscillator signal at a first frequency and a frequency divider having a division ratio that is fixed during operation. The frequency divider is supplied with the RF oscillator signal and is configured to provide an oscillator signal at a second frequency. The apparatus further has a monitor circuit, to which the oscillator signal at the second frequency is supplied and which is configured to measure the second frequency and to provide at least one digital value that is dependent on the second frequency of the oscillator signal. The at least one digital value is provided on a test contact.

Interfaces between clock domains of an integrated circuit (IC) depend on synchronization of phase-locked loops (PLLs) that generate clocks in the different domains and on how each PLL responds to jitter in a shared reference clock. The well-controlled same bandwidth (and loop dynamic) for those PLLs renders the same and, therefore, ignorable reference jitter contribution. As a key component that determines a digital PLL bandwidth, digitally controlled oscillator (DCO) may have its gain vary with process, temperature, and supply IR drop from chip to chip or even module to module. A calibration circuit provides a gain correction factor to achieve a nominal gain in DCO as well as a desired/target PLL loop bandwidth. In some examples, the calibration circuit in each PLL determines a gain correction factor that causes the PLLs to have a common jitter response and stores the gain correction factors in the calibration circuits.

This disclosure relates to an apparatus, system, and method for generating uplink transmissions using a polar architecture including a phase locked loop with potential for two point injection. According to some embodiments, frequency resources allocated for a transmission may be determined. A cartesian baseband signal may be generated for the uplink transmission. The cartesian baseband signal may be converted to a polar baseband signal, including a baseband phase signal and an amplitude signal. Modulation parameters, potentially including whether to use one point injection or two point injection with a phase locked loop, may be determined. The baseband phase signal may be upconverted to an RF phase signal according to the determined modulation parameters. The RF phase signal may be amplified according to the amplitude signal to produce an RF signal. The RF signal may be transmitted.

Various methods provide for trimming the gain in a dual-port phase-locked loop (PLL) of a radio transceiver. Use is made of the radio's demodulator to perform modulation accuracy measurements, thereby reducing the cost and complexity of external test equipment.

A chirp-generator comprising a phase-detector for providing a phase-difference-signal representative of a phase difference between a clock-input-signal and a feedback-signal. A VCO-circuit is configured to provide a chirp-generator-output-signal based on the phase-difference-signal. The VCO-circuit comprises a switched-varactor-bank, which includes a plurality of varactors, and a varactor-switch associated with each of the plurality of varactors. The varactor-switch is configured to selectively control whether or not the associated varactor contributes to the capacitance of the VCO-circuit, based on the state of a varactor-control-signal. The chirp-generator also includes a feedback-component configured to: receive the chirp-generator-output-signal; and apply a variable-multiplication-factor to the chirp-generator-output-signal in order to provide the feedback signal for the phase-detector. A controller provides a sequence of different variable-multiplication-factors to the feedback-component; and provides varactor-control-signals to the plurality of varactors such that the varactors are sequentially controlled such that they contribute to the capacitance of the VCO-circuit.

A circuit includes an RF oscillator coupled in a phase-locked loop. The phase-locked loop is configured to receive a digital input signal, which is a sequence of digital words, and to generate a feedback signal for the RF oscillator based on the digital input signal. The circuit further includes a digital-to-analog conversion unit that includes a pre-processing stage configured to pre-process the sequence of digital words and a digital-to-analog-converter configured to convert the pre-processed sequence of digital words into the analog output signal. The circuit includes circuitry configured to combine the analog output signal and the feedback signal to generate a control signal for the RF oscillator. The pre-processing stage includes a word-length adaption unit configured to reduce the word-lengths of the digital words and a sigma-delta modulator coupled to the word-length adaption unit downstream thereof and configured to modulate the sequence of digital words having reduced word-lengths.

The method for calibrating the frequency synthesizer using two-point FSK modulation consists, in a first phase, in supplying an excitation signal generated by a calibration unit to a sigma-delta modulator by deactivating a digital-to-analog converter and transmitting the output signal from a loop filter of the synthesizer to the calibration unit, which digitally converts the incoming signal and offsets the phase shift between the excitation signal and the loop filter output signal in the calibration unit. In a second phase, the excitation signal is supplied to the sigma-delta modulator and to the activated digital-to-analog converter, and the digital-to-analog converter gain is calibrated by checking, in the calibration unit, the polarity of the loop filter output signal with respect to the excitation signal, and using a dichotomy algorithm.

A digitally controlled oscillator (DCO) modulation apparatus and method provides a wideband phase-modulated signal output. An exemplary modulator circuit uses an oscillator in a phase-locked loop. The circuit receives a wrapped-phase input signal, unwraps the wrapped-phase input signal to generate an unwrapped-phase signal, and differentiates the unwrapped-phase signal. The wrapped-phase input signal and the differentiated unwrapped-phase signal are both injected into a feedback loop of the modulator circuit. The feedback loop may include a multi-modulus frequency divider with a frequency divisor that is temporarily incremented or decremented to cancel out abrupt phase jumps associated with the wrapped-phase to unwrapped-phase conversion.