Phase shift circuit and phase correcting method
View Patent ↗A phase shift circuit includes a 45° phase corrector that performs vector synthesis of signals supposed to have a 45° phase difference, out of a plurality of sets of orthogonal phase signals having an about 45° phase difference and an equal amplitude, the orthogonal phase signals in each set having undergone 90° phase correction, and outputs signals resulting from the vector synthesis, whereby a phase error between the orthogonal phase signals in the different sets is eliminated by the vector synthesis to make it possible to correct their phase difference to accurately 45°.
1. A phase shift circuit comprising a 45° phase corrector that is supplied with a plurality of sets of orthogonal phase signals in which each set consists of respective first and second orthogonal phase signals, each having undergone a 90° phase correction and which have an about 45° phase difference and an equal amplitude, relative to respective first and second orthogonal phase signals of a different set of the plurality of sets of orthogonal phase signals, and that performs vector synthesis of signals supposed to have a 45° phase difference, out of the supplied sets of orthogonal phase signals, to output signals resulting from the vector synthesis.
2. The phase shift circuit according to claim 1 , wherein said 45° phase corrector performs amplitude correction to correct an amplitude error of the signals resulting from the vector synthesis.
3. The phase shift circuit according to claim 1 , further comprising respective 90° phase correctors that perform the 90° phase correction of the respective sets of orthogonal phase signals, each set consisting of first and second orthogonal phase signals, to supply the resultant signals to said 45° phase corrector.
4. The phase shift circuit according to claim 3 , further comprising a phase shifter that phase-shifts an input signal by an integral multiple of 45° and supplies output signals generated by the phase shifter to said 90° phase correctors.
5. The phase shift circuit according to claim 4 , wherein said phase shifter supplies said 90° phase corrector with at least 4-phase signals having successive, relative phase differences of about 0°, about 450°, about 90°, and about 135°.
6. The phase shift circuit according to claim 5 , wherein said phase shifter supplies said 90° phase corrector with 8-phase signals including reverse-phase signals of the respective 4-phase signals.
7. The phase shift circuit according to claim 3 , further comprising:
a 45° phase shifter that phase-shifts a differential input signal by 45°; and
a 90° phase shifter that phase-shifts an output signal of said 45° phase shifter by 90° and supplies said 90° phase corrector with signals generated by the phase shifter.
8. The phase shift circuit according to claim 3 , further comprising:
a 45° phase shifter that phase-shifts an input signal to generate first and second sets of output signals having an about 45° phase difference;
a first 90° phase shifter that phase-shifts the first output signal to generate a third and a fourth output signal having an about 90° phase difference; and
a second 90° phase shifter that phase-shifts the second output signal to generate a fifth and a sixth output signal having an about 90° phase difference,
wherein the third, fourth, fifth, and sixth output signals are supplied to said 90° phase corrector.
9. The phase shift circuit according to claim 3 , wherein said 45° phase corrector has a plurality of adders each adding signals supposed to have a 45° phase difference, out of the orthogonal phase signals having undergone the 90° phase correction.
10. The phase shift circuit according to claim 9 , wherein said 45° phase corrector further has a limiter amplifier performing amplitude limiting of output signals of the adders.
11. The phase shift circuit according to claim 9 , wherein said 90° phase corrector comprises:
an adder performing addition and subtraction of the two signals constituting each set of the orthogonal phase signals; and
a limiter amplifier performing amplitude limiting of an output signal of the adder.
12. The phase shift circuit according to claim 4 , wherein said phase shifter has a plurality of circuits each constituted of a resistor and a capacitor connected in series, and the plural circuits are connected in parallel to a signal line through which the input signal is supplied.
13. A phase shift circuit comprising a plurality of first adders each of which receives two signals supposed to have a 45° phase difference, out of a plurality of sets of orthogonal phase signals having an about 45° phase difference and an equal amplitude, relative to respective first and second orthogonal phase signals of a different set of the plurality of sets of orthogonal phase signals, the orthogonal phase signals in each set having undergone a 90° phase correction, and adds the two signals to output an addition result.
14. The phase shift circuit according to claim 13 , further comprising a first limiter amplifier that is constituted of multi-stage amplifiers connected to one another and receiving the outputs of said first adders.
15. The phase shift circuit according to claim 14 , further comprising:
a second adder that receives two signals constituting orthogonal phase signals and outputs a sum signal of the two signals;
a third adder that receives the two signals constituting the orthogonal phase signals and outputs a difference signal of the two signals; and
a second limiter amplifier that is constituted of multi-stage amplifiers connected to one another and receives the outputs of said second and third adders to supply output signals to said first adders.
16. A phase correcting method, comprising:
a 45° correction step of performing vector synthesis of signals supposed to have a 45° phase difference, out of a plurality of sets of supplied orthogonal phase signals having an about 45° phase difference and an equal amplitude, relative to respective first and second orthogonal phase signals of a different set of the plurality of sets of orthogonal phase signals, the orthogonal phase signals in each set having undergone 90° phase correction, to generate signals having a 45° phase difference.
17. The phase correcting method according to claim 16 , further comprising an amplitude correction step of performing amplitude correction of the signals generated in said 45° correction step.
18. The phase correcting method according to claim 16 , further comprising a 90° correction step of generating the orthogonal phase signals with a 90° phase difference used in said 45° correction step by using two signals constituting orthogonal phase signals.