Main challenges are; Dynamic range, power consumption, reference clock generation and input data bandwidth. Associated challenges due to limited dynamic range are; SFDR, NPR and accumulated phase-noise due to noise floor. Power consumption is a result of the extensive input data rate which is the major draw-back of the current available RF DACs.
A direct sampling DAC could generate multiple frequency bands simultaneously if desired. The main benefit though is the flexibility (in what frequency bands to use and sub-channel bandwidth) and the high order of integration. If the overall dynamic range of the DAC is large enough, output power control per sub-channel is also achievable. The oversampling gain also works in favour for multi-Giga-sample DACs by increasing the effective-number-of-bits.
Targeted accumulated usable bandwidth with current technology is set to 500 MHz bandwidth, distributed at any desired frequency (within assigned band). This limitation comes from the available dynamic range together with regulatory requirements. Usage of up to Ka-band is targeted, enabled by a sample rate of 67 Gsps, low intrinsic jitter and high analogue bandwidth.
The system architecture is based on an evaluation platform from a vendor supplying these types of components. The transmitter line-up is analysed and characterized but not build. The system setup aims to enable verification of a multiple set of user cases proving, when verified, the usability of the RF DAC component with the limitations of the current available technology.
This study has three phases:
Presently the Requirements have been consolidated and possible technologies have been compared for technology selection on PM1 after Requirements Establishment phase, going a little ahead of schedule and including part of the next phase. The plan is to be able to procure the selected device (and board) and prepare for the Technology Demonstration.