Unidirectional sampling mixer
View Patent ↗A unidirectional sampling mixer utilizes a stepped phase modulation to shift the frequency of an RF input signal supplied to an RF input switch. An ordered set of phase shift values to be applied to the RF input signal and a set of times each element of which corresponds to a time at which a phase shift value is be applied to the RF signal are determined. For each phase shift value, a controller controls the RF input switch to select an input of a phase shifting device and controls an RF output switch to select an output of the phasing shifting device. The input and the output of the phase shifting device are selected to apply the phase shift value at its corresponding time to the RF input signal. A frequency shifted signal is supplied to an RF output port from an output of the RF output switch.
1. A method for shifting a frequency of a radio frequency (RF) signal in a selected direction, the method comprising:
supplying an RF input signal to a first RF input switch from an RF input port;
determining an ordered set of phase shift values to be applied to the RF input signal;
determining a set of times each element of which corresponds to a time at which a phase shift value is to be applied to the RF signal;
for each phase shift value within the ordered set of phase shift values:
controlling the first RF input switch to select an input of a first phase shifting device and controlling a second RF input switch to select an input of a second phase shifting device, wherein the input of the first phase shifting device and the input of the second phase shifting device are selected to apply the phase shift value at its corresponding time to the RF input signal; and
supplying the output of the first phase shifting device to the second phase shifting device via the second RF input switch; and
supplying to an RF output port a frequency shifted signal from an output of the second phase shifting device.
2. The method of claim 1 , wherein the frequency shifted signal is higher in frequency than the RF input signal.
3. The method of claim 1 , wherein the frequency shifted signal is lower in frequency than the RF input signal.
4. The method of claim 1 , wherein the RF input signal is a modulated signal.
5. The method of claim 1 , wherein the phase shifting device is selected from the group consisting of a 90 degree hybrid, a 180 degree balun and a spatially-modulated antenna structure.
6. An apparatus to shift a frequency of a radio frequency (RF) signal in a selected direction, the apparatus comprising:
a first RF input switch configured to receive an RF input signal from an RF input port;
a first phase shifting device, wherein an output of the first RF input switch is electrically connected to an input of the first phase shifting device;
a second RF input switch;
a second phase shifting device, wherein an input of the second RF input switch is electrically connected to an output of the first phase shifting device and wherein an output of the second RF input switch is electrically connected to an input of the second phase shifting device; and
a controller, wherein the controller is electrically connected to the first and second input switches and is configured to perform operations comprising:
receiving an ordered set of phase shift values to be applied to the RF input signal;
receiving a set of times each element of which corresponds to a time at which a phase shift value is to be applied to the RF signal;
for each phase shift value within the ordered set of phase shift values, controlling the first RF input switch to select an input of the first phase shifting device and controlling the second RF input switch to select an input of the second phasing shifting device, wherein the input of the first phase shifting device and the input of the second phase shifting device are selected to collectively apply the phase shift value at its corresponding time to the RF input signal;
directing the RF input signal to the first phase shifting device via the first input switch; and
directing the output of the first phase shifting device to the second phase shifting device via the second input switch,
wherein the second phase shifting device is configured for sending a frequency shifted signal to an RF output port.
7. The apparatus of claim 6 , wherein the frequency shifted signal is higher in frequency than the RF input signal.
8. The apparatus of claim 6 , wherein the frequency shifted signal is lower in frequency than the RF input signal.
9. The apparatus of claim 6 , wherein the RF input signal is a modulated signal.
10. The apparatus of claim 6 , wherein the phase shifting device is selected from the group consisting of a 90 degree hybrid, a 180 degree balun and a spatially-modulated antenna structure.