In current digital wireless systems, the traditional up-conversion chain (or significant portion thereof) is primarily analog and includes types such as super-heterodyne, low intermediate frequency (IF) and zero IF up-conversion technology. These technologies start with the conversion of inherently digital signals to analog signals through high performance digital-to-analog (D/A) converters, generally due to the higher frequencies involved. Once converted to the analog domain, various combinations of analog filters, amplifiers, mixers and modulators (and perhaps other analog elements) are cascaded to achieve the up-conversion from the output of the A/D converter(s) to the radio frequency (RF) band of interest (transmit RF signal).
Likewise, on the receiver side, the traditional down-conversion chain (or significant portion thereof) is primarily analog including such types as super-heterodyne, low IF and zero IF down-conversion technology. To achieve the down-conversion, various combinations of analog filters, amplifiers, mixers and demodulators (and perhaps other analog elements) are utilized to achieve the conversion from the RF band of interest (receive RF signal) to the input to A/D converter(s).
Component variation, tolerances, and aging all affect the design requirements, costs, and manufacturability of the analog up-conversion (transmitter) and down-conversion (receiver) chains. Accordingly, there is needed a digital transmitter and digital receiver that utilizes digital technology for the up-conversion and down-conversion chains.