Direct quadrature modulation, as shown in Figure 4, is a common form of direct conversion used in the transmit path.
The previously shown example of a generic direct quadrature modulation transmit architecture can be used for any type of modulation.
The model RF9958 IC offers quadrature modulation
, transmit AGC amplification and upconversion in a single QSOP-28 plastic package, The models RF9957 and RF2667 ICs feature receive AGC amplification and quadrature demodulation in a single QSOP-24 plastic package.
This contributes to superior signal-to-noise ratio when transmitting a digitally encoded signal using quadrature modulation
techniques such as IBOC DAB.
5 utilizes the existing I/Q modem from the PRISM II chip set, the HFA3783, which features all the necessary blocks for quadrature modulations
and demodulation of "I" and "Q" baseband signals.