Systems and methods to provide upconverting with notch filtering
A system includes: a baseband phase generator configured to receive differential in-phase (I) and quadrature (Q) signals and configured to output N phase-shifted baseband signals, wherein N is greater than 4, further wherein the baseband phase generator comprises a plurality of notch filters configured to receive the I and Q signals; and an upconverter configured to receive the phase-shifted baseband signals, to perform mixing on the phase-shifted baseband signals, and to output a differential upconverted signal.
1. A radio frequency (RF) transmit path comprising:
means for generating differential in-phase (I) and quadrature (Q) baseband signals;
means for generating N phase-shifted baseband signals from the I and Q baseband signals through use of a plurality of notch filters, wherein N is greater than 4; and
means for upconverting the phase shifted baseband signals to produce a plurality of RF signals.
2. The RF transmit path of claim 1 , further comprising:
means for summing a first set of the plurality of RF signals to generate a first output signal; and
means for summing a second set of the plurality of RF signals to generate a second output signal.
3. The RF transmit path of claim 2 , further comprising:
means for generating a single-ended RF signal from the first and second output signal.
4. The RF transmit path of claim 1 , wherein the means for generating differential I and Q baseband signals comprises:
a plurality of digital to analog converters (DACs) configured to receive I and Q digital signals and to output differential analog I and Q signals; and
a plurality of low-pass filters configured to receive the differential analog I and Q signals and to output the differential I and Q baseband signals
wherein a frequency notch of the notch filters corresponds to a frequency of alias of the DACs.
5. The RF transmit path of claim 1 , wherein the plurality of notch filters comprises a plurality of twin-T notch filters.
6. The RF transmit path of claim 1 , wherein the means for upconverting comprises N mixers, where each of the mixers is configured to receive a respective one of the phase shifted baseband signals and a local oscillator (LO) signal.