RF-DAC cell and method for providing an RF output signal

A radio frequency digital to analog converter (RF-DAC) cell,

• wherein the RF-DAC cell is configured to generate an RF output signal based on a baseband signal, a first signal and a second signal, and
• wherein the first signal has a first duty cycle and toggles between first predefined amplitude values and the second signal has a second duty cycle smaller than the first duty cycle and toggles between second, predefined amplitude values;
• and
• a power amplifier stage configured to amplify the RF output signal,
• wherein the power amplifier stage and the RF-DAC cell is integrated into a common circuit, and wherein an input of the power amplifier stage is connected to the output of the RF-DAC cell without a transformer provided therebetween.

An RF-DAC cell, comprising:

• a first output configured to output a first RF output signal;
• a second output configured to output a second RF output signal shifted by substantially half of a LO period with respect to the first RF output signal;
• a main cell including:
• a first current source and a second current source configured to be activated in response to a digital control signal derived from a digital baseband signal, and to provide, when activated, a first current;
• and
• a first switch and a second switch connected between the first current source and second current source, respectively, and ground, and configured to be activated in response to a first LO signal and a second LO signal being shifted by substantially half of a LO period of the first LO signal, respectively, and to cause, when activated, the first and second current sources to output the first current to the first and second outputs, respectively;
• and
• an auxiliary cell including:
• a third current source and a fourth current source configured to be activated by the digital control signal, and to provide, when activated, a second current;
• and
• a third switch and a fourth switch connected between the third current source and fourth current source, respectively, and ground, and configured to be activated by a third LO signal and a fourth LO signal being shifted by substantially half of a LO period of the third LO signal, the third and fourth LO signals having a duty cycle smaller than the first and second LO signals and to cause, when activated, the third and fourth current sources to output the second current to the first and second outputs, respectively,
• wherein the first and second outputs are configured to combine the first and second currents from the first current source and the third current source and from the second current source and the fourth current source, respectively, into the first RF output signal and into the second RF output signal.

A method for producing an RF output signal, the method comprising:

• generating an RF output signal based on a baseband signal, a first signal and a second signal,
• wherein the first signal has first duty cycle and toggles between first predefined amplitude values,
• wherein the second signal has a second duty cycle smaller than the first duty cycle and toggles between second predefined amplitude values, and
• wherein the second predefined amplitude values are less than or are greater than the first predefined amplitude values.