Method of self-calibration in a wireless transmitter

• US 20050159116A1
• Filed: 02/07/2005
• Published: 07/21/2005
• Est. Priority Date: 06/28/2002
• Status: Abandoned Application

• Current Assignee: Wei Xiong
• Original Assignee: Wei Xiong
• Inventors: Xiong, Wei
• Application Number:
  US11/052,991
• Publication Number:
  US 20050159116A1
• Time in Patent Office: Days
• US Class Current: 455/127.100
• CPC Class Codes: H04B 17/13 of power amplifiers, e.g. gain or non-linearity
• CPC Class Codes: H04W 52/36 with a discrete range or set of values, e.g. step size, ramping or offsets
• CPC Class Codes: H04W 52/50 at the moment of starting communication in a multiple access environment
• CPC Class Codes: H04W 52/52 using AGC [Automatic Gain Control] circuits or amplifiers

Abstract

A method of self-calibration of a wireless LAN communication device includes entering a self-calibration mode when the device is powered up or commanded by software. A packet stream is transmitted at an initial transmit power level. The packet stream may comprise standard data packets. The transmit power level may be monitored from data packet to data packet; and adjusted in steps by setting a transmit gain using a control voltage adjustment determined according to a transmit gain variation so as to make the step size as large as possible without exceeding a predetermined maximum step size. The transmit power level is, thus, adjusted so as not to exceed a predetermined maximum allowable level. The transmit power level is then adjusted to a desired level. Lower desired transmit power levels may be set by shifting bits in a digital-to-analog converter and setting the transmit gain for a higher transmit power level.

Claims

1. A transmitter comprising:

a variable gain amplifier having a gain controlled by a control voltage;

a power detector for monitoring a transmit power level of said transmitter and converting said transmit power level to a measurement voltage;

an analog-to-digital converter for converting said measurement voltage to a digital value;

a baseband processor, said baseband processor receiving said digital value and producing said control voltage while providing an output signal comprising a packet stream to said variable gain amplifier, wherein said baseband processor adjusts said control voltage during transmission of said packet stream, said control voltage effecting an adjustment to said transmit power level via said variable gain amplifier, said adjustment made from an initial transmit power level by a step size so as not to exceed a predetermined maximum allowable transmit power level; and

wherein said baseband processor adjusts said control voltage so as to adjust said transmit power level to a desired transmit power level.

2. The transmitter of claim 1, wherein said adjustment is determined according to a transmit gain variation so as to make said step size as large as possible without exceeding a predetermined maximum step size.

3. The transmitter of claim 2 wherein said transmit gain variation comprises a part-to-part variation.

4. The transmitter of claim 2 wherein said transmit gain variation comprises a variation due to changes in transmit frequency.

5. The transmitter of claim 2 wherein said transmit gain variation comprises a supply voltage variation.

6. The transmitter of claim 2 wherein said transmit gain variation comprises a variation due to changes in ambient temperature.

7. The transmitter of claim 1 wherein an error value is saved in a lookup table and a gain control is offset with said error value to compensate for a part-to-part variation, thereby reducing a worst case number of times said adjustment to said transmit power level by a step size is made.

8. The transmitter of claim 1 wherein said predetermined maximum allowable transmit power level is in accordance with an 802.11b standard.

9. The transmitter of claim 1 wherein said transmit power level is adjusted to a lower desired transmit power level by shifting bits in a digital-to-analog converter and setting a transmit gain for a higher transmit power level.

10. The transmitter of claim 1 wherein said packet stream comprises at least one packet and said control voltage is adjusted while said packet is being transmitted.

11. The transmitter of claim 1 wherein said packet stream comprises a plurality of packets and said control voltage is adjusted from packet to packet.

12. The transmitter of claim 1 wherein said packet stream comprises an initially transmitted packet and said initially transmitted packet is a null packet.

13. The transmitter of claim 1 wherein said packet stream comprises an initially transmitted packet and said initially transmitted packet is a standard data packet.

14. The transmitter of claim 1 wherein said transmit power level is adjusted to a desired transmit power level by linear extrapolation using a linearizer table.

15. A wireless communication device comprising a transmitter and a receiver, said transmitter comprising:

a variable gain amplifier having a gain controlled by a control voltage;

a power detector for monitoring a transmit power level of said transmitter and converting said transmit power level to a measurement voltage;

an analog-to-digital converter for converting said measurement voltage to a digital value;

a baseband processor, said baseband processor receiving said digital value and producing said control voltage while providing an output signal comprising a packet stream to said variable gain amplifier, wherein said baseband processor adjusts said control voltage during transmission of said packet stream, said control voltage effecting an adjustment to said transmit power level via said variable gain amplifier, said adjustment made from an initial transmit power level by a step size so as not to exceed a predetermined maximum allowable transmit power level; and

wherein said baseband processor adjusts said control voltage so as to adjust said transmit power level to a desired transmit power level.

16. The wireless communication device of claim 15, wherein said adjustment is determined according to a transmit gain variation so as to make said step size as large as possible without exceeding a predetermined maximum step size.

17. The wireless communication device of claim 16 wherein said transmit gain variation comprises a part-to-part variation.

18. The wireless communication device of claim 17 wherein an error value is saved in a lookup table and a gain control is offset with said error value to compensate for a part-to-part variation, thereby reducing a worst case number of times said adjustment to said transmit power level by a step size is made.

19. The wireless communication device of claim 15 wherein said predetermined maximum allowable transmit power level is in accordance with an 802.11b standard.

20. The wireless communication device of claim 15 wherein said transmit power level is adjusted to a lower desired transmit power level by shifting bits in a digital-to-analog converter and setting a transmit gain for a higher transmit power level.

21. The wireless communication device of claim 15 wherein said packet stream comprises a plurality of packets and said control voltage is adjusted from packet to packet.

22. A communication system comprising:

a local area network having an access point;

a wireless communication device for communication with said local area network via said access point, wherein said wireless communication device comprises a transmitter and a receiver, said transmitter comprising;

a variable gain amplifier having a gain controlled by a control voltage;

a power detector for monitoring a transmit power level of said transmitter and converting said transmit power level to a measurement voltage;

an analog-to-digital converter for converting said measurement voltage to a digital value;

a baseband processor, said baseband processor receiving said digital value and producing said control voltage while providing an output signal comprising a packet stream to said variable gain amplifier, wherein said baseband processor adjusts said control voltage during transmission of said packet stream, said control voltage effecting an adjustment to said transmit power level via said variable gain amplifier, said adjustment made from an initial transmit power level by a step size so as not to exceed a predetermined maximum allowable transmit power level; and

wherein said baseband processor adjusts said control voltage so as to adjust said transmit power level to a desired transmit power level.

23. The communication system of claim 22, wherein said adjustment is determined according to a transmit gain variation so as to make said step size as large as possible without exceeding a predetermined maximum step size.

24. The communication system of claim 23 wherein said transmit gain variation comprises a part-to-part variation.

25. The communication system of claim 24 wherein an error value is saved in a lookup table and a gain control is offset with said error value to compensate for a part-to-part variation, thereby reducing a worst case number of times said adjustment to said transmit power level by a step size is made.

26. The communication system of claim 22 wherein said predetermined maximum allowable transmit power level is in accordance with an 802.11b standard.

27. The communication system of claim 22 wherein said transmit power level is adjusted to a lower desired transmit power level by shifting bits in a digital-to-analog converter and setting a transmit gain for a higher transmit power level.

28. The communication system of claim 22 wherein said packet stream comprises a plurality of packets and said control voltage is adjusted from packet to packet.