Method and apparatus for controlling a harmonic rejection mixer
View Patent ↗In one embodiment, the present invention includes a method for receiving a radio frequency (RF) signal and mixing the RF signal with a master clock to obtain a mixed signal, cyclically rotating the mixed signal to each of N gain stages for at least one cycle of the master clock, and summing the outputs of the N gain stages to provide an output signal.
1. An apparatus comprising:
a master radio frequency (RF) device to receive an incoming RF signal and provide an RF output, the master RF device modifying the incoming RF signal;
a master local oscillator (LO) device coupled to an output of the master RF device, the master LO device to receive the RF output and mix the RF output with a master clock signal to obtain a mixed signal;
a rotating switch device coupled to the master LO device to cyclically switch the mixed signal to one of a plurality of output ports of the rotating switch device;
circuitry coupled to each of the plurality of output ports for performing gaining, filtering and weighting of the mixed signal and providing a plurality of outputs; and
a summer coupled to the plurality of outputs of the circuitry to generate a summer output.
2. The apparatus of claim 1 , wherein the master LO device comprises a plurality of metal oxide semiconductor field effect transistors (MOSFETs) each having a first terminal to receive the RF output from the master RF device, a gate terminal to receive the master clock signal, and a second terminal to output the mixed signal.
3. The apparatus of claim 2 , wherein the rotating switch device comprises a plurality of rotating switches each comprising a transistor to receive the mixed signal from the second terminal of the corresponding MOSFET and to output the mixed signal when the transistor is enabled by a control signal, wherein a value of the control signal is changed when a value of the master clock signal is at a low state.
4. The apparatus of claim 1 , wherein the incoming RF signal is from an antenna source.
5. The apparatus of claim 1 , wherein the incoming RF signal is from cable distribution.
6. The apparatus of claim 1 , further comprising:
a low-pass filter coupled to the summer output for filtering the summer output and providing a filter output; and
an analog-to-digital converter coupled to the filter output to digitize the filter output and provide a tuner output signal.
7. The apparatus of claim 6 , further comprising:
a demodulator having an input coupled to the tuner output signal to further process the tuner output signal.
8. The apparatus of claim 7 , further comprising:
a display coupled to the demodulator, the display forming a television.
9. A method comprising:
receiving an incoming RF signal, modifying the incoming RF signal, and providing an RF output;
mixing the RF output with a master clock signal to obtain a mixed signal;
using a rotating switch device to cyclically switch the mixed signal to one of a plurality of output ports;
performing gaining, filtering and weighting of the mixed signal at each of a plurality of output ports of the rotating switch device and providing a plurality of outputs; and
summing the plurality of outputs to generate a summer output.
10. The method of claim 9 , further comprising:
low pass filtering the summer output to provide a filtered output; and
converting the filtered output from an analog form to a digital form to provide a tuned output signal.
11. The method of claim 10 , further comprising:
demodulating the tuned output signal to provide a further processed tuned output signal.
12. The method of claim 11 , further comprising:
displaying the further processed tuned output signal as a television signal.