The analog interface circuits in this reference design are often used between current-source based digital-to analog converters (DAC) and quadrature modulators. While the DAC348x is used as an example of a TI high-speed DAC, the circuits can be applied to other current-source based converters with slight modifications. The DAC348x and TRF3705 analog interface are populated by default on the TSW308xEVMs. Both the DAC348x and TRF3705 are designed with the same DC bias and AC swing specification to provide a seamless interface. Other circuit topologies are described to account for other DC bias and AC swing specifications. By accounting the correct DC bias and proper AC swing, system designers can apply these circuits based on their application needs in order to achieve optimal performance.
- A breakdown of the interface on the TSW308x is explained to show the direct connection between the DAC3484 and TRF3705
- General Design equations of current source DACs with IQ modulators are provided and explained
- TINA spice models are provided for different interface networks for DC, AC, and filtered interfaces to meet customer needs