Phase adjustment technique

• US 20010006543A1
• Filed: 12/22/2000
• Published: 07/05/2001
• Est. Priority Date: 12/24/1999
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Koizumi, Shinji, Asakawa, Masakazu
• Granted Patent: US 6,433,604 B2
• Time in Patent Office: Days
• US Class Current: 375/371
• CPC Class Codes: H04L 27/364 Arrangements for overcoming imperfections in the modulator, e.g. quadrature error or unbalanced I and Q levels

Abstract

An adjustment technique allowing easy adjustment of a phase shifter is disclosed. A programmable logic device (PLD) is connected to the phase shifter so as to correct a standard vector depending on correction data written thereto. When supplying a standard input signal to the phase shifter, the phase and amplitude of the output signal is measured. A standard vector for a sequentially selected one of a plurality of phase points is generated and outputted to the phase shifter. Correction data for a selected phase point is calculated based on the measured phase and amplitude. A VHDL source program is generated from the corrected data for all the phase points to write the correction data into the PLD.

Claims

1. An endless phase shifter comprising

a phase shifter for shifting a phase of an output signal depending on a phase control signal;

and

a programmable logic device (PLD) connected to the phase shifter, for correcting a standard vector depending on correction data to output a corrected vector as the phase control signal to the phase shifter, wherein the correction data is written into the PLD through a download connector connected to a computer.

2. A system for adjusting a phase shifter, comprising:

a programmable logic device (PLD) connected to the phase shifter, for correcting a standard veactor depending on correction data written thereto;

an analyzer for supplying a standard input signal to the phase shifter and analyzing an output signal of the phase shifter to measure phase and amplitude of the output signal; and

a processor for generating a standard vector for a sequentially selected one of a plurality of phase points to output it to the phase shifter, calculating correction data for a selected phase point based on the measured phase and amplitude obtained by the analyzer, and generating a writer for writing correction data for all the phase points into the programmable logic device.

3. The system according to

claim 2

, wherein the processor writes predetermined data in the PLD to set the PLD for a through state where the standard vector passes through the PLD to the phase shifter.

4. The system according to

claim 3

, wherein the standard vector is transferred from the processor to the PLD through a download connector.

5. The system according to

claim 2

, wherein the writer in a data writing program which is automatically generated depending on the correction data for all the phase points.

6. The system according to

claim 5

, wherein the data writing program is described in a hardware description language (HDL).

7. The system according to

claim 2

, wherein the processor calculates correction data for each of a plurality of previously selected phase points and then calculates correction data for all the phase points by estimating correction data for phase points positioned between adjacent ones of the selected phase points using interpolation.

8. A method for adjusting a phase shifter, comprising the steps of:

a) providing tho phase shifter with a standard vector for a sequentially selected one of a plurality of phase points;

b) analyzing an output signal of the phase shifter to measure phase and amplitude of the output signal with respect to an input standard signal;

c) calculating correction data for a selected phase point based on the measured phase and amplitude;

d) storing correction data for all the phase points; and

e) writing the correction data in a programmable logic device (PLD) so as to provide the phase shifter with a corrected vector for each of the phase points.

9. The method according to

claim 8

, wherein the step (c) comprises the steps of:

c.1) determining whether the measured phase and amplitude fall into a predetermined range;

c.2) when the measured phase and amplitude fall out of the predetermined range, generating an updated vector by changing the standard vector based on errors between the measured phase and amplitude and the predetermined range;

c.3) providing the phase shifter with the updated vector;

c.4) repeating the steps (b), (c.1), (c.2), and (c.3) until the measured phase and amplitude fall into the predetermined range;

c.5) when the measured phase and amplitude fall into the predetermined range, calculating correction data based on the updated vector and the standard vector.

10. The method according to

claim 9

, wherein the step (c) further comprises the step of:

c.6) calculating correction data for phase points positioned between adjacent ones of the selected phase points using interpolation.

11. The method according to

claim 8

, wherein the step (a) comprises the steps of:

e.1) automatically generating a data writing program depending on the correction data for all the phase points; and

e.2) writing the correction data in the programmable logic device (PLD) by executing the data writing program.

12. The method according to

claim 11

, wherein the data writing program is described in a hardware description language (HDL).

13. The method according to

claim 8

, wherein the PLD has been set to a through state where data passes through the PLD to the phase shifter before the step (a).

14. The method according to

claim 11

, wherein the step (c) comprises the steps of:

c.1) determining whether the measured phase and amplitude fall into a predetermined range;

c.2) when the measured phase and amplitude fall out of the predetermined range, generating an updated vector by changing the standard vector based on errors between the measured phase and amplitude and the predetermined range;

c.3) providing the phase shifter with the updated vector;

c.4) repeating the steps (b), (c.1), (c.2), and (c.3) until the measured phase and amplitude fall into the predetermined range;

c.5) when the measured phase and amplitude fall into the predetermined range, calculating correction data based on the updated vector and the standard vector.