Digital-to-analog converters may be used for a wide variety of applications, including wireless transmitters. Conventional wireless transmitters may first pass a digital signal through a digital-to-analog converter to convert the digital signal to an analog signal, and then pass the analog signal through filters, mixers, and amplification stages to generate a transmission signal at a desired radio frequency (RF). Recently, direct digital-to-RF converters have simplified wireless transmitters by combining digital-to-analog conversion with RF upconversion. Such direct digital-to-RF converters have significant advantages, e.g., fewer components, improved accuracy, smaller footprint, etc. When used in high power applications, however, direct digital-to-RF converters may have a high current consumption. Because current draw from the power supply converts to supply power voltage based on the corresponding resistance, and because the direct digital-to-RF converter transforms variations in the power supply to noise, the high current consumption and the corresponding resistance limits the maximum output power available with a direct digital-to-RF converter. Further, when the direct digital-to-RF converter has an IQ modulation structure, the In-phase (I) and Quadrature (Q) branches act as loads for each other, which limits the maximum signal level achievable by the direct digital-to-RF converter. For example, the I and Q branches deliver an out-of-phase signal, which reduces the maximum output power relative to in phase operation. Thus, there remains a need for improved direct digital-to-RF converters for high power and/or IQ applications.
USPTO Backgrounds
USPTO Backgrounds