Digital-to-time converter and methods for generating phase-modulated signals

A digital-to-time converter (DTC) arranged to generate a fine phase-modulated output signal based on a control word, the DTC comprising:

• a programmable divider to divide an oscillator signal to generate first and second divider signals;
• a resample circuitry comprising a rising-edge resampling logic to sample the first divider signal to provide a rising-edge correlated signal and comprising a falling-edge resampling logic to sample a divider unit output signal to provide a falling-edge correlated signal;
• a divider unit arranged to provide one of the second divider signal and a delayed version of the second divider signal as the divider unit output signal;
• a first selection unit to select between the rising-edge correlated signal and the falling-edge correlated signal based on first and second predetermined bits of the control word to generate a first edge signal;
• a second selection unit to select between the rising-edge correlated signal and the falling-edge correlated signal based on the second predetermined bits of the control word;
• a delay element to delay an output of the second selection unit by a quarter cycle to generate a second edge signal;
• and
• an interpolator to generate the fine phase-modulated output signal based on an edge interpolation between the first and second edge signals.

A method for generating a fine phase-modulated output signal based on a control word, the method comprising:

• performing a “divide by 2N+/−1 operation” an oscillator signal to generate first and second divider signals whose frequencies are 1/(2N+1) and 1/(2N−1) of a frequency of the oscillator signal, where N is a whole number;
• sampling the first divider signal to provide a rising-edge correlated signal;
• sampling a divider unit output signal to provide a falling-edge correlated signal;
• providing one of the second divider signal and a delayed version of the second divider signal as the divider unit output signal;
• selecting between the rising-edge correlated signal and the falling-edge correlated signal based on first and second predetermined bits of a control word to generate a first edge signal;
• selecting between the rising-edge correlated signal and the falling-edge correlated signal based on the second predetermined bits of the control word;
• delaying an output of the second selection unit by a quarter cycle to generate a second edge signal;
• and
• generating the fine phase-modulated output signal based on an edge interpolation between the first and second edge signals.

A digital transmitter comprising:

• a digital power amplifier (P/A) arranged to generate wireless signals based on an amplitude control signal and a phase-modulated signal;
• and
• a digital-to-time converter (DTC) arranged to generate the fine phase-modulated output signal based on a control word,
• wherein the DTC comprises:
• a multi-modulus divider (MMD) arranged to perform a “divide by 2N+/−1 operation” on an oscillator signal to generate divider signals whose frequencies are 1/(2N+1) and 1/(2N−1) of a frequency of the oscillator signal, where N is a whole number;
• logic circuitry arranged to sample the divider signals to provide rising and falling edge correlated signals, and select between the rising and falling edge correlated signals based on first and second predetermined bits of a control word to generate edge signals;
• and
• an edge interpolator arranged to generate the fine phase-modulated output signal based on an edge interpolation between the edge signals.