EP0265218A2
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EP
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Vector modulators and calibration thereof
Assignee: HP Inc
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Filing: 1987-10-20
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Granted: —
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Expires: 2007-10-20
Abstract
Abstract Calibration of a vector modulator is done using a scalar detector (220) to measure the amplitude of the RF output signal, phase shifters (221, 223) to adjust the relative phases of the I and Q components of the RF carrier, and variable attentuators (225, 227) in the I and Q modulation signal input lines to adjust the relative amplitude of the modulation signals. DC signal sources provide reference signals for the I and Q modulation inputs, carrier leak compensation signals, and calibration signals for balancing the amplitude of the I and Q modulation signals. An iterative four step calibration process is followed until no change in the results is observed. The quadrature phase error is minimized by adjusting the phase shifters (221, 223). The carrier leakage is minimized by adjusting the carrier leak compensation sources (229, 231) to minimize RF output with the modulation inputs grounded (247, 247). The amplitudes of the I and Q modulation signals are balanced by adjusting the attenuators (225, 227) until the output amplitudes are equal. Finally, the quadrature calibration signal sources (235, 237) are adjusted until the output amplitudes they produce are balanced.
Inventors
- 👤 Allen P. Edwards
- 👤 David R. Gildea
- 👤 Chung Yiu Lau
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 19:49
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/32; H04L27/34; H04L27/36; H04L27/362; H04L27/364; G; G01; G01R; G01R35/00; G01R35/005; H04L27/0014; H04L2027/0016; H04L2027/0018
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
106 words
A method of calibrating a vector modulator having a input power divider (13), in-phase (I) (15) and quadrature (Q) (17) mixers, I and Q modulation signals, and an output power combiner (19), characterised by injecting quadrature calibration signals and measuring with a detector (220) the amplitude of an RF output signal in carrying out the following steps: (a) minimizing the quadrature phase error; (b) minimizing the carrier leakage; (c) balancing the amplitudes of the I and Q modulated signals; (d) balancing the amplitudes of the quadrature calibration signals (Qc+, Qc-; Ic+ and Ic-) and (e) repeating steps (a) through (d) until no further changes are observed.
Claim 2
Independent Claim
106 words
A method of calibrating a vector modulator having a input power divider (13), in-phase (I) (15) and quadrature (Q) (17) mixers, I and Q modulation signals, and an output power combiner (19), characterised by injecting quadrature calibration signals and measuring with a detector (220) the amplitude of an RF output signal in carrying out the following steps: (a) minimizing the quadrature phase error; (b) minimizing the carrier leakage; (c) balancing the amplitudes of the I and Q modulated signals; (d) balancing the amplitudes of the quadrature calibration signals (Qc+, Qc-; Ic+ and Ic-) and (e) repeating steps (a) through (d) until no further changes are observed.
Claim 3
Dependent Claim
117 words
The calibration method of claim 1 wherein: step (a) is performed by sequentially connecting combinations of positive DC reference signals (Qc+, Ic+), and negative DC reference signals (Qc-, Ic-) to the I and Q mixers (215, 217) in place of the modulation signals, measuring the RF output amplitude for each of the four combinations of reference signals, and adjusting phase shifters (221, 223) located between the power divider (213) and the mixers (215, 217) so that the sum of the RF output amplitudes produced by the positive DC reference signals (Qc+, Ic+) and the negative DC reference signals (Qc-, Ic-) combinations is equal to the sum of the RF output amplitudes produced by the reference signal combinations.
Claim 4
Dependent Claim
53 words
The calibration method of claim 1, wherein step (b) is performed by connecting carrier leak compensation sources (229, 231) to the I and Q mixers (215, 217) with the modulation inputs grounded (245, 247), measuring the RF output amplitude and adjusting the carrier leak compensation sources (229, 231) to minimize RF output amplitude.
Claim 5
Dependent Claim
52 words
The calibration method of claim 1, wherein step (c) is performed by alternately grounding (245, 247) the I and Q modulation inputs while measuring the RF output amplitude, and adjusting attenuators (225, 227) connected between the modulation signal inputs and the mixers (215, 217) until the RF output amplitudes produced are equal.
Claim 6
Dependent Claim
117 words
The calibration method of claim 1, wherein step (d) is performed by alternately applying the Qc+ and Qc- signals to the Q mixer (217) with the I modulation signal connected to the I mixer (215), measuring the RF output amplitude and adjusting the amplitude of one of the Qc+ or Qc- signals until the output amplitudes they produce are equal, then alternately applying the Ic+ and Ic- signals to the I mixer (215) with the quadrature modulation signal connected to the Q mixer (217), measuring the RF output amplitude and adjusting the amplitudes of the Ic+ or Ic-signals until the output amplitudes they produce are equal to the output amplitude produced by the Qc+ and Qc- signals.
Claim 7
Dependent Claim
122 words
The calibration method of claim 3 wherein the RF output amplitude is minimized in step (b) by: measuring the RF output while varying the amplitude of the carrier leak compensation signal; selecting a first carrier leak compensation interpolation amplitude near one side of the RF output minimum, in a region where the RF response has measurable slope, producing a first RF output amplitude; selecting a second carrier leak compensation interpolation amplitude near the other side of the RF output minimum, in a region where the RF response has measurable slope, producing an RF output amplitude equal to the first RF output amplitude; and setting the amplitude of the carrier leak compensation signal at the average of the first and second interpolation amplitudes.
Claim 8
Dependent Claim
136 words
A vector modulator wherein an input RF source (11) is connected to an input power divider (13) providing two outputs, each of which is independently connected to a mixer (215, 217), one of the mixers is connected to an in-phase (I) signl path and the other mixer is connected to a quadrature (Q) signal path, and the outputs from the mixers are connected to a power combiner (219) producing an output RF signal, characterised by an adjustable phase shifter (221, 223) connected between the power divider (213) and the mixers (215, 217); sources of quadrature calibration signals (235, 237) and of carrier leak compensation signals (229, 231) connected to the mixers (215, 217); variable attenuators (225, 227) between modulation inputs to the mixers; and a signal detector (220) connected to the output of the combiner (219).
Claim 9
Dependent Claim
136 words
A vector modulator wherein an input RF source (11) is connected to an input power divider (13) providing two outputs, each of which is independently connected to a mixer (215, 217), one of the mixers is connected to an in-phase (I) signl path and the other mixer is connected to a quadrature (Q) signal path, and the outputs from the mixers are connected to a power combiner (219) producing an output RF signal, characterised by an adjustable phase shifter (221, 223) connected between the power divider (213) and the mixers (215, 217); sources of quadrature calibration signals (235, 237) and of carrier leak compensation signals (229, 231) connected to the mixers (215, 217); variable attenuators (225, 227) between modulation inputs to the mixers; and a signal detector (220) connected to the output of the combiner (219).
References Cited (Backward Citations)
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