Automatic gain control circuit and method thereof and demodulation apparatus using the same

An automatic gain control circuit for control of an amplification gain of a reception signal comprised of a data signal to the header part of which is added a burst portion including at least a preamble signal and having the preamble signal divided into two stages of a front half section and a rear half section, comprising:

• an automatic gain control amplifier for amplifying the reception signal with a gain in accordance with a gain control signal;
• a reception signal power monitor for receiving and detecting a power of the reception signal;
• a delay unit for delaying an output derived from the automatic gain control amplifier by a predetermined time;
• a burst detector for performing correlation between the output derived from the automatic gain control amplifier and the output signal of the delay unit to detect the burst portion of the reception signal, and to output a first burst synchronization detection signal when the front half section of the preamble signal is detected and output a second burst synchronization detection signal when the rear half section of the preamble signal is detected;
• and
• an amplification gain controller for outputting the gain control signal to the automatic gain control amplifier, said gain control signal having first, second and third gains, in sequence, said first gain being set in advance in response to a trigger signal indicating the start of burst detection, said second gain being calculated as a function of the power of the reception signal detected by the reception signal power monitor in response to the first burst synchronization detection signal from the burst detector, and said third gain being calculated as a function of the power of the reception signal produced at the output of the automatic gain control amplifier at the time the gain control signal has said second gain and in response to the second burst synchronization detection signal from the burst detector.

An automatic gain control circuit for control of an amplification gain of a reception signal comprised of a data signal to the header part of which is added a burst portion including at least a preamble signal, comprising:

• an automatic gain control amplifier for amplifying the reception signal with a gain in accordance with a gain control signal;
• an analog-to-digital converter for converting an output signal of the automatic gain control amplifier from an analog signal to a digital signal;
• a reception signal power monitor for receiving and detecting a power of the reception signal;
• a delay unit for delaying the output derived from the automatic gain control amplifier by a predetermined time;
• a burst detector for performing correlation between the digital signal from the analog-to-digital converter and an output signal of the delay unit to detect the burst portion of the reception signal and output a first burst synchronization detection signal;
• and
• an amplification gain controller for outputting the gain control signal to the automatic gain control amplifier, said gain control signal having first, second and third gains, in sequence, said first gain being set in advance in response to a trigger signal indicating the start of burst detection, said second gain being calculated as a function of the power of the reception signal detected by the reception signal power monitor, said amplification gain controller integrating the digital signal from the analog-to-digital converter when the automatic gain control amplifier amplifies the reception signal with the second gains and said third gain being calculated as a function of said integrated digital signal from said analog-to-digital converter in response to the first burst synchronization detection signal from the burst detector.

An automatic gain control circuit for control of an amplification gain of a reception signal comprised of a data signal to the header part of which is added a burst portion including at least a preamble signal and having the preamble signal divided into two stages of a front half section and a rear half section, comprising:

• an automatic gain control amplifier for amplifying the reception signal with a gain in accordance with a gain control signal;
• an analog-to-digital converter for converting an output signal of the automatic gain control amplifier from an analog signal to a digital signal;
• a reception signal power monitor for receiving and detecting a power of the reception signal;
• a delay unit for delaying an output derived from the automatic gain control amplifier by a predetermined time;
• a burst detector for performing correlation between the digital signal from the analog-to-digital converter and an output signal of the delay unit to detect the burst portion of the reception signal, to output a first burst synchronization detection signal when the front half section of the preamble signal is detected, and to output a second burst synchronization detection signal when the rear half section of the preamble signal is detected;
• and
• an amplification gain controller for outputting the gain control signal to the automatic gain control amplifier, said gain control signal having first, second and third gains, in sequence, said first gain being set in advance in response to a trigger signal indicating the start of burst detection, said second gain being calculated as a function of the power of the reception signal detected by the reception signal power monitor in response to the first burst synchronization detection signal from the burst detector, said amplification gain controller integrating the digital signal from the analog-to-digital converter when the automatic gain control amplifier amplifies the reception signal with the second gains and said third gain being calculated as a function of said integrated digital signal from said analog-to-digital converter in response to the second burst synchronization detection signal from the burst detector.

An automatic gain control method for control of an amplification gain of a reception signal comprised of a data signal to the header part of which is added a burst portion including at least a preamble signal, comprising the steps of:

• setting the amplification gain so as to amplify the reception signal with a first gain set in advance when starting burst detection,
• amplifying the reception signal with the first gain when burst detection is started and detecting a power of the reception signal,
• calculating a second gain based on detected reception signal power value and setting the amplification gain so as to amplify the reception signal with the second gain,
• finding the power value of the reception signal amplified with the second gain,
• performing burst detection based on a correlation operation between the reception signal amplified with the second gain and a delay signal of the reception signal, and
• calculating a third gain based on the reception signal power value amplified with the found second gain when burst is detected and setting the amplification gain so as to amplify the reception signal with the third gain.

An automatic gain control method for control of an amplification gain of a reception signal comprised of a data signal to the header part of which is added a burst portion including at least a preamble signal and having the preamble signal divided into two stages of a front half section and a rear half section, comprising the steps of:

• setting the amplification gain so as to amplify the reception signal with a first gain set in advance when starting burst detection,
• amplifying the reception signal with the first gain when burst detection is started and detecting a power of the reception signal,
• performing burst detection of the front half section of the preamble signal based on a correlation operation between the reception signal amplified with the first gain and a delay signal of the reception signal,
• calculating a second gain based on detected reception signal power value when a burst in the front half section is detected and setting the amplification gain so as to amplify the reception signal with the second gain,
• finding the power value of the reception signal amplified with the second gain,
• performing burst detection of the rear half section of the preamble signal based on a correlation operation between the reception signal amplified with the second gain and the delay signal of the reception signal, and
• calculating a third gain based on the reception signal power value amplified with the found second gain when a burst in the rear half section is detected and setting the amplification gain so as to amplify the reception signal with the third gain.

A demodulation apparatus for control of an amplification gain of a reception signal comprised of a data signal to the header part of which is added a burst portion including at least a preamble signal and demodulating the reception signal after amplification, including:

• an automatic gain control circuit having an automatic gain control amplifier for amplifying the reception signal with a gain in accordance with a gain control signal;
• a reception signal power monitor for receiving and detecting a power of the reception signal;
• a delay unit for delaying the output derived from the automatic gain control amplifier by a predetermined time;
• a burst detector for performing correlation between the output signal derived from the automatic gain control amplifier and the output signal of the delay unit to detect the burst portion of the reception signal and output a burst synchronization detection signal;
• and
• an amplification gain controller for outputting the gain control signal to the automatic gain control amplifier, said gain control signal having first, second and third gains, in sequence, said first gain being set in advance in response to a trigger signal indicating the start of burst detection, said second gain being calculated as a function of the power of the reception signal detected by the reception signal power monitor, and said third gain being calculated as a function of the power of the reception signal produced at the output of the automatic gain control amplifier at the time the gain control signal has said second gain and in response to the burst synchronization detection signal from the burst detector.

A demodulation apparatus for control of an amplification gain of a reception signal comprised of a data signal to the header part of which is added a burst portion including at least a preamble signal and having the preamble signal divided into two stages of a front half section and a rear half section and demodulating the reception signal after amplification, including:

• an automatic gain control circuit having an automatic gain control amplifier for amplifying the reception signal with a gain in accordance with a gain control signal;
• a reception signal power monitor for receiving and detecting a power of the reception signal;
• a delay unit for delaying an output derived from the automatic gain control amplifier by a predetermined time;
• a burst detector for performing correlation between an output signal derived from the automatic gain control amplifier and the output signal of the delay unit to detect the burst portion of the reception signal, and to output a first burst synchronization detection signal when the front half section of the preamble signal is detected and output a second burst synchronization detection signal when the rear half section of the preamble signal is detected;
• and
• an amplification gain controller for outputting the gain control signal to the automatic gain control amplifier, said gain control signal having first, second and third gains, in sequence, said first gain being set in advance in response to a trigger signal indicating the start of burst detection, said second gain being calculated as a function of the power detected by the reception signal power monitor in response to the first burst synchronization detection signal from the burst detector, and said third gain being calculated as a function of the power of the reception signal produced at the output of the automatic gain control amplifier at the time the gain control signal has said second gain and in response to the second burst synchronization detection signal from the burst detector.

A demodulation apparatus for control of an amplification gain of a reception signal comprised of a data signal to the header part of which is added a burst portion including at least a preamble signal and demodulating the reception signal after amplification, including:

• an automatic gain control circuit having an automatic gain control amplifier for amplifying the reception signal with a gain in accordance with a gain control signal;
• an analog-to-digital converter for converting an output signal of the automatic gain control amplifier from an analog signal to a digital signal;
• a reception signal power monitor for receiving and detecting a power of the reception signal;
• a delay unit for delaying the output derived from the automatic gain control amplifier by a predetermined time;
• a burst detector for performing correlation between the digital signal from the analog-to-digital converter and an output signal of the delay unit to detect the burst portion of the reception signal and output a burst synchronization detection signal;
• and
• an amplification gain controller for outputting the gain control signal to the automatic gain control amplifier, said gain control signal having first, second and third gains, in sequence, said first gain being set in advance in response to a trigger signal indicating the start of burst detection, said second gain being calculated as a function of the power of the reception signal detected by the reception signal power monitor, said amplification gain controller integrating the digital signal from the analog-to-digital converter when the automatic gain control amplifier amplifies the reception signal with the second gain, and said third gain being calculated as a function of said integrated digital signal from said analog-to-digital converter in response to the burst synchronization detection signal from the burst detector.

A demodulation apparatus for control of an amplification gain of a reception signal comprised of a data signal to the header part of which is added a burst portion including at least a preamble signal and having the preamble signal divided into two stages of a front half section and a rear half section and demodulating the reception signal after amplification, including:

• an automatic gain control circuit having an automatic gain control amplifier for amplifying the reception signal with a gain in accordance with a gain control signal;
• an analog-to-digital converter for converting the output signal of the automatic gain control amplifier from an analog signal to a digital signal;
• a reception signal power monitor for receiving and detecting a power of the reception signal;
• a delay unit for delaying the output derived from the automatic gain control amplifier by a predetermined time;
• a burst detector for performing correlation between the digital signal from the analog-to-digital converter and an output signal of the delay unit to detect the burst portion of the reception signal, to output a first burst synchronization detection signal when the front half section of the preamble signal is detected, and to output a second burst synchronization detection signal when the rear half section of the preamble signal is detected;
• and
• an amplification gain controller for outputting the gain control signal to the automatic gain control amplifier, said gain control signal having first, second and third gains, in sequence, said first gain being set in advance in response to a trigger signal indicating the start of burst detection, said second gain being calculated as a function of the power of the reception signal detected by the reception signal power monitor in response to the first burst synchronization detection signal from the burst detector, said amplification gain controller integrating the digital signal from the analog-to-digital converter when the automatic gain control amplifier amplifies the reception signal with the second gain, and said third gain being calculated as a function of said integrated digital signal from said analog-to-digital converter in response to the second burst synchronization detection signal from the burst detector.