An apparatus includes a signal generator. The signal generator includes a voltage controlled oscillator (VCO) coupled to provide an output signal having a frequency. The signal generator further includes an asymmetric divider coupled to receive the output signal of the VCO and to provide an output signal. The output signal of the asymmetric divider has a frequency that is half the frequency of the output signal of the VCO. The asymmetric divider presents a balanced load to the VCO.

Apparatus and methods for interfacing with a micro-electromechanical system (MEMS) sensor are provided. In an example, an apparatus can interface circuit including an integrator circuit, a sample switch circuit, a saturation detector and a controller. The saturation detector can be configured to receive a signal indicative of an integration of charge of the sensor, to compare the signal indicative of the integration of charge to an integrator saturation threshold and to modulate a divide parameter using the comparison of the signal indicative of the integration of charge and the integrator saturation threshold. The controller can be configured to receive a clock signal and to control the sample switch circuit based on a phase of the clock signal and the divide parameter.

A circuit includes a counter circuit, a logic circuit, and a clock divider. The counter circuit includes a clock divider counter to be loaded with most significant bits of a divider value, and decremented at a same edge of each pulse of a clock signal. The logic circuit compares a value contained in the divider counter to a reference value and generates an end count signal as a function of the value contained in the divider counter matching the reference value, and transitions a toggle signal at a same edge of each pulse of the end count signal. The clock divider counter is reloaded with the most significant bits of the divider value as a function of the end count signal. The clock divider generates a divided version of the clock signal as a function of the toggle signal.

A circuit includes a counter circuit, a logic circuit, and a clock divider. The counter circuit includes a clock divider counter to be loaded with most significant bits of a divider value, and decremented at a same edge of each pulse of a clock signal. The logic circuit compares a value contained in the divider counter to a reference value and generates an end count signal as a function of the value contained in the divider counter matching the reference value, and transitions a toggle signal at a same edge of each pulse of the end count signal. The clock divider counter is reloaded with the most significant bits of the divider value as a function of the end count signal. The clock divider generates a divided version of the clock signal as a function of the toggle signal.

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.

A time-to-digital converter (TDC) circuitry is disclosed for converting a phase difference between an input reference signal (109) and an input clock signal (110) to a digitally represented output signal (139). The TDC circuitry comprises a plurality of constituent TDC:s (101, 102, 103), a reference signal provider (120), and a digital signal combiner (130). Each constituent TDC is configured to convert a phase difference between a constituent reference signal (181, 182, 183) and a constituent clock signal (110) to a digitally represented constituent output signal (131, 132, 133). The reference signal provider (120) is configured to provide the respective constituent reference signals (181, 182, 183) to each of the constituent TDC:s (101, 102, 103). In at least a parallel operation mode of the TDC circuitry, each respective constituent reference signal comprises a respectively delayed version of the input reference signal (109) with different respective delays for at least two of the respective constituent reference signals. The digital signal combiner (130) is configured to provide the digitally represented output signal (139) based on the digitally represented constituent output signals (131, 132, 133) of the constituent TDC:s. A corresponding method and devices comprising the TDC circuitry are also disclosed.

A time-to-digital converter (TDC) circuitry is disclosed for converting a phase difference between an input reference signal (109) and an input clock signal (110) to a digitally represented output signal (139). The TDC circuitry comprises a plurality of constituent TDC:s (101, 102, 103), a reference signal provider (120), and a digital signal combiner (130). Each constituent TDC is configured to convert a phase difference between a constituent reference signal (181, 182, 183) and a constituent clock signal (110) to a digitally represented constituent output signal (131, 132, 133). The reference signal provider (120) is configured to provide the respective constituent reference signals (181, 182, 183) to each of the constituent TDC:s (101, 102, 103). In at least a parallel operation mode of the TDC circuitry, each respective constituent reference signal comprises a respectively delayed version of the input reference signal (109) with different respective delays for at least two of the respective constituent reference signals. The digital signal combiner (130) is configured to provide the digitally represented output signal (139) based on the digitally represented constituent output signals (131, 132, 133) of the constituent TDC:s. A corresponding method and devices comprising the TDC circuitry are also disclosed.

Methods and apparatus for generating phase-shifted clock signals from a reference clock, connecting the phase-shifted clock signals to a counter module so that the phase-shifted clock signals change values in counters in the counter module, and combining the values in the counters to generate an output signal corresponding to an amount of time. One or more events can be detected at a time corresponding to the output signal. In embodiments, pulses can be transmitted and received at a measure time to evaluate connected devices.

Methods and apparatus for generating phase-shifted clock signals from a reference clock, connecting the phase-shifted clock signals to a counter module so that the phase-shifted clock signals change values in counters in the counter module, and combining the values in the counters to generate an output signal corresponding to an amount of time. One or more events can be detected at a time corresponding to the output signal. In embodiments, pulses can be transmitted and received at a measure time to evaluate connected devices.

An automatic frequency calibration and lock detection circuit includes a frequency error generator circuit, an automatic frequency calibration signal generator circuit, and a lock flag generator circuit. The frequency error generator circuit generates a frequency error signal based on a reference frequency signal and an output frequency signal. The frequency error signal represents a difference between a frequency of the output frequency signal and a target frequency. The automatic frequency calibration signal generator circuit generates an automatic frequency calibration output signal and an automatic frequency calibration done signal based on the frequency error signal and a first clock signal. The lock flag generator circuit generates a lock done signal based on the frequency error signal, the automatic frequency calibration done signal and a second clock signal. The frequency error generator circuit is shared by the automatic frequency calibration signal generator circuit and the lock flag generator circuit.