Quadrature signal generator having digitally-controlled phase and amplitude correction

Claim 2

A quadrature signal generator, comprising: a frequency synthesizer for receiving an input signal and generating an output signal having a predetermined frequency, the output signal having amplitude error components; a splitter for receiving the output signal and generating an in-phase (I) signal and a quadrature phase (Q) signal at the predetermined frequency, the in-phase and quadrature phase signals having a substantially 90° phase difference; a table look-up memory for receiving the input signal as an address input and in response thereto generating a digital correction word; digital-to-analog conversion means for receiving the digital correction word and in response thereto generating a predetermined phase correction signal; means for receiving the phase correction signal and the in-phase signal and in response thereto generating a phase error correction signal; means for adding the phase error correction signal to the quadrature phase signal to correct the phase error; and amplitude correction means for receiving the in-phase and phase error corrected quadrature-phase signals for correction of the amplitude error components.

Claim 3

The quadrature signal generator as described in claim 1 wherein said amplitude correction means comprises: addressable memory means for receiving the input signal as an address input and in response thereto generating a predetermined amplitude correction word; and means responsive to said predetermined amplitude correction word for attenuating the in-phase and quadrature-phase signals to correct the amplitude error components.

Claim 4

A quadrature signal generator, comprising: a frequency synthesizer for receiving an input signal and generating an output signal having a predetermined frequency, the output signal having amplitude error components; a splitter for receiving the output signal and generating an in-phase (I) signal and a quadrature-phase (Q) signal at the predetermined frequency, the in-phase and quadrature-phase signals having a substantially 90° phase difference; phase-locked loop means for receiving the in-phase signal and generating a control signal; a table look-up memory for receiving the control signal as an address input and in response thereto generating a digital correction word; digital-to-analog conversion means for receiving the digital correction word and in response thereto generating a predetermined phase correction signal; means for receiving the phase correction signal and the in-phase signal and in response thereto generating a phase error correction signal; means for adding the phase error correction signal to the quadrature-phase signal to correct the phase error; and amplitude correction means receiving the in-phase and phase error corrected quadrature-phase signals for correction of amplitude error components.

Claim 5

A quadrature signal generator, comprising: a frequency synthesizer for receiving an input signal and generating an output signal having a predetermined frequency, the output signal having amplitude error components; a splitter for receiving the output signal and generating an in-phase (I) signal and a quadrature-phase (Q) signal at the predetermined frequency, the in-phase and quadrature-phase signals having a substantially 90° phase difference; phase-locked loop means for receiving the in-phase signal and generating a control signal; a table look-up memory for receiving the control signal as an address input and in response thereto generating a digital correction word; digital-to-analog conversion means for receiving the digital correction word and in response thereto generating a predetermined phase correction signal; means for receiving the phase correction signal and the in-phase signal and in response thereto generating a phase error correction signal; means for adding the phase error correction signal to the quadrature-phase signal to correct the phase error; and amplitude correction means receiving the in-phase and phase error corrected quadrature-phase signals for correction of amplitude error components.

Claim 6

The quadrature signal generator as described in claim 3 wherein said phase-locked loop means comprises: a voltage-controlled oscillator for generating an oscillator signal; a phase comparator for comparing the oscillator signal and the in-phase signal and in response thereto generating a comparator output signal; and means for integrating the phase comparator output signal to generate an analog version of the control signal, said control signal being applied to the voltage-controlled oscillator.

Claim 7

The quadrature signal generator as described in claim 4 wherein the phase-locked loop means further includes an analog-digital convertor for converting the analog version of the control signal to digital form.

Claim 8

A quadrature signal generator, comprising: a frequency synthesizer for receiving an input signal and generating an output signal having a predetermined frequency, the output signal having amplitude error components; a splitter for receiving the output signal and generating an in-phase (I) signal and a quadrature-phase (Q) signal at the predetermined frequency, the in-phase and quadrature-phase signals having a substantially 90° phase difference; means responsive to the in-phase signal and the quadrature-phase signal and including a table look-up memory for receiving the input signal as an address input for correcting any phase error between the in-phase signal and the quadrature-phase signal; a second table look-up memory for receiving the input signal as an address input and in response thereto generating a predetermined amplitude correction word; and means responsive to the predetermined amplitude correction word for attenuating the in-phase and phase error corrected quadrature-phase signals for correcting the amplitude error components.

Claim 9

A quadrature signal generator, comprising: a frequency synthesizer for receiving an input signal and generating an output signal having a predetermined frequency, the output signal having amplitude error components; a splitter for receiving the output signal and generating an in-phase (I) signal and a quadrature-phase (Q) signal at the predetermined frequency, the in-phase and quadrature-phase signals having a substantially 90° phase difference; means responsive to the in-phase signal and the quadrature-phase signal and including a table look-up memory for receiving the input signal as an address input for correcting any phase error between the in-phase signal and the quadrature-phase signal; a second table look-up memory for receiving the input signal as an address input and in response thereto generating a predetermined amplitude correction word; and means responsive to the predetermined amplitude correction word for attenuating the in-phase and phase error corrected quadrature-phase signals for correcting the amplitude error components.

Claim 10

A digitally-controlled quadrature signal generator, comprising: a frequency synthesizer for receiving a digital input signal and in response thereto generating an output signal having a predetermined frequency, the output signal having amplitude error components; a splitter for receiving the output signal and in response thereto generating an in-phase (I) signal and a quadrature-phase (Q) signal at the predetermined frequency, the in-phase and quadrature-phase signals having a substantially 90° phase difference; a first table look-up memory for receiving the digital input signal as an address input and in response thereto generating a digital correction word; digital-to-analog conversion means for receiving the digital correction word and in response thereto generating a predetermined phase correction signal for correction of any phase error in the quadrature-phase signal; a mixer for receiving the phase correction signal and the in-phase signal and in response thereto generating a phase error correction signal; an adder for adding the phase error correction signal to the quadrature-phase signal to cancel said phase error by causing the phase difference between said in-phase and quadrature-phase signals to be equal to 90°; and amplitude correction means for receiving the in-phase and phase error corrected quadrature-phase signals for the correction of amplitude error components.

Claim 11

A digitally-controlled quadrature signal generator, comprising: a frequency synthesizer for receiving a digital input signal and in response thereto generating an output signal having a predetermined frequency, the output signal having amplitude error components; a splitter for receiving the output signal and in response thereto generating an in-phase (I) signal and a quadrature-phase (Q) signal at the predetermined frequency, the in-phase and quadrature-phase signals having a substantially 90° phase difference; a first table look-up memory for receiving the digital input signal as an address input and in response thereto generating a digital correction word; digital-to-analog conversion means for receiving the digital correction word and in response thereto generating a predetermined phase correction signal for correction of any phase error in the quadrature-phase signal; a mixer for receiving the phase correction signal and the in-phase signal and in response thereto generating a phase error correction signal; an adder for adding the phase error correction signal to the quadrature-phase signal to cancel said phase error by causing the phase difference between said in-phase and quadrature-phase signals to be equal to 90°; and amplitude correction means for receiving the in-phase and phase error corrected quadrature-phase signals for the correction of amplitude error components.

Claim 12

The digitally-controlled quadrature signal generator as described in claim 7 wherein said amplitude correction means comprises: a second table look-up memory for receiving the input signal as an address input and in response thereto generating a predetermined amplitude correction word; and means responsive to said predetermined amplitude correction word for attenuating the in-phase and quadrature-phase signals for correction of the amplitude error components.

Claim 13

The digitally-controlled quadrature signal generator as described in claim 7 further including a power divider connected between the splitter and the mixer.

Claim 14

The digitally-controlled quadrature signal generator as described in claim 8 wherein each of said table look-up memories is a read only memory having a plurality of predetermined correction words at addressable locations stored therein.

Claim 15

A digitally-controlled quadrature signal generator, comprising: a frequency synthesizer for receiving a digital input signal and in response thereto generating an output signal having a predetermined frequency, the output signal having amplitude error components; a splitter for receiving the output signal and in response thereto generating an in-phase (I) signal and a quadrature-phase (Q) signal, the in-phase and quadrature-phase signals having a substantially 90° phase difference; phase-locked loop means for receiving the in-phase signal and generating a control signal; a table look-up memory for receiving the control signal as an address input and in response thereto generating a digital correction word; digital-to-analog conversion means for receiving the digital correction word and in response thereto generating a predetermined phase correction signal for correction of any phase error in the quadrature- phase signal; a power divider for receiving the in-phase signal and generating a plurality of replicas thereof; a mixer for receiving the phase correction signal and a replica of the in-phase signal and in response thereto generating a phase error correction signal; an adder for adding the phase error correction signal to the quadrature-phase signal to correct the phase error; and amplitude correction means for receiving the in-phase and phase error corrected quadrature-phase signals to thereby cancel said amplitude error components.

Claim 16

A digitally-controlled quadrature signal generator, comprising: a frequency synthesizer for receiving a digital input signal and in response thereto generating an output signal having a predetermined frequency, the output signal having amplitude error components; a splitter for receiving the output signal and in response thereto generating an in-phase (I) signal and a quadrature-phase (Q) signal, the in-phase and quadrature-phase signals having a substantially 90° phase difference; phase-locked loop means for receiving the in-phase signal and generating a control signal; a table look-up memory for receiving the control signal as an address input and in response thereto generating a digital correction word; digital-to-analog conversion means for receiving the digital correction word and in response thereto generating a predetermined phase correction signal for correction of any phase error in the quadrature- phase signal; a power divider for receiving the in-phase signal and generating a plurality of replicas thereof; a mixer for receiving the phase correction signal and a replica of the in-phase signal and in response thereto generating a phase error correction signal; an adder for adding the phase error correction signal to the quadrature-phase signal to correct the phase error; and amplitude correction means for receiving the in-phase and phase error corrected quadrature-phase signals to thereby cancel said amplitude error components.