RF Phase Shifter
Embodiments of a Radio Frequency (RF) phase shifter are disclosed. In one embodiment, an RF phase shifter comprises a first transformer comprising a primary winding coupled to a first RF port of the RF phase shifter and a secondary winding that is magnetically coupled to the primary winding. The RF phase shifter further comprises at least one capacitor circuit having a first terminal coupled to the secondary winding of the first transformer and a second terminal coupled to a primary winding of a second transformer. The RF phase shifter and combiner further comprises the second transformer, where the primary winding of the secondary transformer is coupled to the second terminal of the at least one capacitor circuit, and a secondary winding of the second transformer is coupled to a second RF port of the RF phase shifter.
1 . A Radio Frequency, RF, phase shifter comprising:
a first transformer comprising:
a primary winding coupled to a first RF port of the RF phase shifter; and
a secondary winding that is magnetically coupled to the primary winding;
at least one capacitor circuit having:
a first terminal coupled to the secondary winding of the first transformer; and
a second terminal coupled to a primary winding of a second transformer;
the second transformer comprising:
the primary winding coupled to the second terminal of the at least one capacitor circuit; and
a secondary winding coupled to a second RF port of the RF phase shifter;
wherein the secondary winding of the first transformer comprises multiple taps; and
the RF phase shifter further comprises switching circuitry that selectively couples at least one of the multiple taps to ground to thereby configure the secondary winding of the first transformer to have one of a plurality of inductance values.
2 . The RF phase shifter of claim 1 wherein at least one parameter of the RF phase shifter is configurable, the at least one parameter comprising:
a) the inductance of the secondary winding of the first transformer;
b) the capacitance of the at least one capacitor circuit;
c) the inductance of the primary winding of the second transformer; or
d) a combination of any two or more of (a)-(c).
3 . The RF phase shifter of claim 1 wherein:
the primary winding of the second transformer comprises multiple taps; and
the RF phase shifter further comprises switching circuitry that selectively couples at least one of the multiple taps of the primary winding of the second transformer to ground to thereby configure the primary winding of the second transformer to have one of a plurality of inductance values.
4 . The RF phase shifter of claim 1 wherein a capacitance of the at least one capacitor circuit is configurable.
5 . The RF phase shifter of claim 1 wherein the first RF port of the RF phase shifter is a differential first RF port.
6 . The RF phase shifter of claim 5 wherein one tap of the primary winding of the first transformer is coupled to a positive port of the differential first RF port and another tap of the primary winding of the first transformer is coupled to a negative port of the differential first RF port.
7 . The RF phase shifter of claim 1 wherein the first RF port of the RF phase shifter is a single-ended first RF port.
8 . The RF phase shifter of claim 7 wherein one tap of the primary winding of the first transformer is coupled to the single-ended first RF port.
9 . The RF phase shifter of claim 5 wherein:
a tap of the secondary winding of the first transformer serves as a single-ended port of the first transformer; and
the at least one capacitor circuit comprises a capacitor circuit having a first terminal that is coupled to the single-ended port of the first transformer and a second terminal coupled to a tap of the primary winding of the second transformer that serves as a single-ended port of the second transformer.
10 . The RF phase shifter of claim 5 wherein:
two taps of the secondary winding of the first transformer serve as a differential port of the first transformer; and
the at least one capacitor circuit comprises:
a first capacitor circuit having a first terminal that is coupled to a positive port of the differential port of the first transformer and a second terminal coupled to a tap of the primary winding of the second transformer that serves as a positive port of a differential port of the second transformer; and
a second capacitor circuit having a first terminal that is coupled to a quadrature-phase port of the differential port of the first transformer and a second terminal coupled to a tap of the primary winding of the second transformer that serves as a quadrature-phase port of the differential port of the second transformer.
11 . The RF phase shifter of claim 5 wherein the second RF port of the RF phase shifter is a single-ended second RF port.
12 . The RF phase shifter of claim 5 wherein the second RF port of the RF phase shifter is a differential second RF port.
13 . The RF phase shifter of claim 1 wherein:
the RF phase shifter is an RF phase shifter and combiner/splitter;
the first RF port is a first split RF port;
the second RF port is a combined RF port;
the second terminal of the at least one capacitor circuit is coupled to a first separate portion of the primary windings of the second transformer; and
the RF phase shifter and combiner/splitter further comprises:
a third transformer comprising:
a primary winding coupled to a second split RF port of the RF phase shifter and combiner/splitter; and
a secondary winding that is magnetically coupled to the primary winding; and
at least one second capacitor circuit having:
a first terminal coupled to the secondary winding of the third transformer; and
a second terminal coupled to a second separate portion of the primary windings of the second transformer.
14 . The RF phase shifter of claim 1 , wherein a phase shift at the second RF port of the RF phase shifter relative to the first RF port of the RF phase shifter is a function of an inductance of the secondary winding of the first transformer, a capacitance of the at least one capacitor circuit, and an inductance of the primary winding of the second transformer.
15 . The RF phase shifter of claim 1 , wherein the phase shift at the second RF port of the RF phase shifter relative to the first RF port of the RF phase shifter is tunable by tuning the inductance of the primary winding of the second transformer.
16 . A phased-array transceiver system comprising:
a plurality of antennas and a plurality of transmit or receive branches; and
a Radio Frequency, RF, phase shifter comprising:
a first transformer comprising:
a primary winding coupled to a first RF port of the RF phase shifter; and
a secondary winding that is magnetically coupled to the primary winding;
at least one capacitor circuit having:
a first terminal coupled to the secondary winding of the first transformer; and
a second terminal coupled to a primary winding of a second transformer; and
the second transformer comprising:
the primary winding coupled to the second terminal of the at least one capacitor circuit; and
a secondary winding coupled to a second RF port of the RF phase shifter;
wherein the secondary winding of the first transformer comprises multiple taps; and
the RF phase shifter further comprises switching circuitry that selectively couples at least one of the multiple taps to ground to thereby configure the secondary winding of the first transformer to have one of a plurality of inductance values.
17 . A wireless communication device comprising a phased-array transceiver system, the phase array transceiver system comprising:
a plurality of antennas and a plurality of transmit or receive branches; and
a Radio Frequency, RF, phase shifter comprising:
a first transformer comprising:
a primary winding coupled to a first RF port of the RF phase shifter; and
a secondary winding that is magnetically coupled to the primary winding;
at least one capacitor circuit having:
a first terminal coupled to the secondary winding of the first transformer; and
a second terminal coupled to a primary winding of a second transformer; and
the second transformer comprising:
the primary winding coupled to the second terminal of the at least one capacitor circuit; and
a secondary winding coupled to a second RF port of the RF phase shifter;
wherein the secondary winding of the first transformer comprises multiple taps; and
the RF phase shifter further comprises switching circuitry that selectively couples at least one of the multiple taps to ground to thereby configure the secondary winding of the first transformer to have one of a plurality of inductance values.
18 . A base station for a radio access network comprising a phased-array transceiver system, the phase array transceiver system comprising:
a plurality of antennas and a plurality of transmit or receive branches; and
a Radio Frequency, RF, phase shifter comprising:
a first transformer comprising:
a primary winding coupled to a first RF port of the RF phase shifter; and
a secondary winding that is magnetically coupled to the primary winding;
at least one capacitor circuit having:
a first terminal coupled to the secondary winding of the first transformer; and
a second terminal coupled to a primary winding of a second transformer; and
the second transformer comprising:
the primary winding coupled to the second terminal of the at least one capacitor circuit; and
a secondary winding coupled to a second RF port of the RF phase shifter; and
wherein the secondary winding of the first transformer comprises multiple taps; and
the RF phase shifter further comprises switching circuitry that selectively couples at least one of the multiple taps to ground to thereby configure the secondary winding of the first transformer to have one of a plurality of inductance values.