Fast and robust AGC apparatus and method using the same
View Patent ↗The present invention discloses apparatus and method for fast and robust automatic gain control (AGC). By using the power statistics and/or the amplitude statistics of multiple pairs of signed ADC outputs, the additional gain control can be determined and included in a statistics-aided AGC to successfully complete the AGC function for a received signal having a dynamic range up to 100 dB within a few micro-seconds.
1. A fast and robust automatic gain control (AGC) apparatus, comprising:
a power detector, electrically connected to a first analog-to-digital converter and a second analog-to-digital converter, used for providing a plurality of measured power (P i ), wherein P i is equal to the sum of squares of a first signed signal (I i ) provided by the first analog-to-digital converter and a second signed signal (Q i ) provided by the second analog-to-digital converter;
a statistics-aided AGC algorithm unit, electrically connected to the first analog-to-digital converter, the second analog-to-digital converter and the power detector, used for determining an additional AGC gain adjustment (Δ Aided ) according to a amplitude statistics of a plurality of M pairs of the first signed signal (I i ) and the second signed signal (Q i ), or a power statistics of the plurality of measured power (P i ), wherein M is an integer from 1 to 100;
a subtractor, electrically connected to the power detector, used for evaluating a power differences between a desired received signal power (P D ) and each of the plurality of measured power (P i ) and providing a plurality of AGC power error signals, wherein the plurality of AGC power error signals are equal to the desired received signal power (P D ) minus the plurality of measured power (P i );
an average unit, electrically connected to the subtractor, used for averaging the plurality of AGC power error signals and providing an average AGC power error signal;
an adder, electrically connected to the average unit and the statistics-aided AGC algorithm unit, used for providing a gain adjustment by adding the additional AGC gain adjustment (Δ Aided ) to the average AGC power error signal;
a multiplier, electrically connected to the adder, used for controlling a AGC loop gain by an adjustable gain (k);
an accumulator, electrically connected to the multiplier, used for tracking a plurality of average AGC power error, adding the plurality of average AGC power error signals up, storing and providing an appropriate digital gain value (G linear ); and
a LNA and VGA control mapping unit, electrically connected to the accumulator, used for converting the appropriate digital gain value (G linear ) into a LNA and VGA gain control signal.
2. The fast and robust apparatus with an automatic gain control (AGC) gain setting as claimed in claim 1 , wherein the accumulator further comprises:
an adder, electrically connected to the multiplier; and
a delay, having an input terminal electrically connected to the adder and an output terminal electrically connected to the adder and the LNA and VGA control mapping unit.
3. A method used for providing an automatic gain control (AGC) gain setting by an amplitude statistic, comprising the steps of:
Step 1: determining an amplitude statistics including a number of a plurality of ADC Most-Significant-Bit (MSB) saturations, a number of a plurality of ADC k-th Most-Significant-Bit (MSB) saturations and a number of an ADC k-th Most-Significant-Bit (MSB) non-saturations within a plurality of M pairs of a first signed signal (I i ,) and a second signed signal (Q i ) from a plurality of analog to digital converters; and
Step2: determining an additional AGC gain adjustment (Δ Aided ) according to the amplitude statistics obtained in step 1.
4. The method used for providing an automatic gain control (AGC) gain setting as claimed in claim 3 , wherein the step of determining the amplitude statistics further comprises the steps of:
if the amplitudes of the first signed signal (I i ) or the second signed signal (Q i ) is equal to 2 N-1 −1 or −2 N-1 , increasing the number of the plurality of ADC Most-Significant-Bit (MSB) saturations by one, wherein N is an integer and is greater than 1;
if the absolute values of the first signed signal (I i ) or the second signed signal (Q i ) is greater than or equal to 2 N-k , increasing the number of the plurality of ADC k-th Most-Significant-Bit (MSB) saturations by one, where k is an integer from 2 to N; and
if the absolute values of the first signed signal (I i ) or the second signed signal (Q i ) is smaller than 2 N-k , increasing the number of the ADC k-th Most-Significant-Bit (MSB) non-saturations by one, where k is an integer from 2 to N.
5. The method used for providing an automatic gain control (AGC) gain setting as claimed in claim 3 , wherein the step of determining an additional AGC gain adjustment (Δ Aided ) further comprises the steps of:
if there are m Most-Significant-Bit (MSB) saturations out of the plurality of M pairs of the first signed signal (I i ) and the second signed signal (Q i ), applying an additional AGC gain adjustment (Δ Aided ), where Δ Aided is a real number from 0 to −30 dB and m is an integer from 0 to M;
if there are m k-th Most-Significant-Bit (MSB) saturations out of the plurality of M pairs of the first signed signal (I i ) and the second signed signal (Q i ), applying an additional AGC gain adjustment (Δ Aided ), where Δ Aided is a real number from −40 to 40 dB, m is an integer from 0 to M, and k is an integer from 2 to N; and
if there are consecutive j sets of the plurality of M pairs of the first signed signal (I i ) and the second signed signal (Q i ) with m k-th MSB non-saturations, applying an additional AGC gain adjustment (Δ Aided ), where Δ Aided is a real number from −40 to 40 dB, j is an integer from 1 to 5, m is an integer from 0 to M, and k is an integer from 2 to N.
6. A method used for providing an automatic gain control (AGC) gain setting by a power statistic, comprising the steps of:
Step1: determining a power statistics including a number of a plurality of ADC Most-Significant-Bit (MSB) power saturations, a number of a plurality of ADC k-th Most-Significant-Bit (MSB) power saturations and a number of ADC k-th Most-Significant-Bit (MSB) power non-saturations within a plurality of M pairs of a first signed signal (I i ) and a second signed signal (Q i ) from a plurality of analog to digital converters; and
Step2: determining an additional AGC gain adjustment (Δ Aided ) according to the power statistics obtained in Step 1.
7. The method used for providing an automatic gain control (AGC) gain setting by a power statistic as claimed in claim 6 , wherein the step of determining the power statistics further comprises the steps of:
if the sum of squares of any pair of the plurality of M pairs of the first signed signal (I i ) and the second signed signal (Q i ) is equal to or greater than 2×(2 N-1 −1), increasing the number of the plurality of ADC Most-Significant-Bit (MSB) power saturations by one, wherein N is an integer and is greater than 1;
if the sum of squares of any pair of the plurality of M pairs of the first signed signal (I i ) and the second signed signal (Q i ) is greater than or equal to 2×2 2(N-k) , increasing the number of the plurality of ADC k-th Most-Significant-Bit (MSB) power saturations by one, where k is an integer from 2 to N; and
if the sum of squares of any pair of the plurality of M pairs of the first signed signal (I i ) and the second signed signal (Q i ) is smaller than 2×2 2(N-k) , increasing the number of ADC k-th Most-Significant-Bit (MSB) power non-saturations by one, where k is an integer from 2 to N.
8. The method used for providing an automatic gain control (AGC) gain setting by a power statistic as claimed in claim 6 , wherein the step of determining an additional AGC gain adjustment (Δ Aided ) further comprises the steps of:
if there are m Most-Significant-Bit (MSB) power saturations out of the plurality of M pairs of the first signed signal (I i ) and the second signed signal (Q i ), applying an additional AGC gain adjustment (Δ Aided ), where Δ Aided is a real number from 0 to −30 dB and m is an integer from 0 to M;
if there are m k-th Most-Significant-Bit (MSB) power saturations out of the plurality of M pairs of the first signed signal (I i ) and the second signed signal (Q i ), applying an additional AGC gain adjustment (Δ Aided ), where Δ Aided is a real number from −40 to 40 dB, m is an integer from 0 to M, and k is an integer from 2 to N; and
if there are consecutive j sets of the plurality of M pairs of the first signed signal (I i ) and the second signed signal (Q i ) with m k-th MSB power non-saturations, applying an additional AGC gain adjustment (Δ Aided ), where Δ Aided is a real number from −40 to 40 dB, j is an integer from 1 to 5, m is an integer from 0 to M, and k is an integer from 2 to N.
9. A wireless communication transceiver with an automatic gain control (AGC), comprising:
an antenna, used for receiving and transmitting a RF signal;
an antenna switch, electrically connected to the antenna and a transmitter;
a RF receiver, electrically connected to the antenna switch, used for providing a first signal and a second signal according to the RF signal; and
a baseband demodulator, electrically connected to the RF receiver, used for providing a LNA and VGA gain control signal to the RF receiver and a demodulated signal;
wherein the baseband demodulator further comprises:
a first N-bit analog-to-digital converter (ADCs), electrically connected to a first plurality of variable gain amplifiers (VGAs), used for converting the first signal output by the first plurality of variable gain amplifiers (VGAs) into an first unsigned signal;
a second N-bit analog-to-digital converter (ADCs), electrically connected to a second plurality of variable gain amplifiers (VGAs), used for converting the second signal output by the second plurality of variable gain amplifiers (VGAs) into an second unsigned signal;
a first analog-to-digital converter, electrically connected to the first N-bit analog-to-digital converter (ADCs), used for converting the first unsigned signal to a first signed signal (I i );
a second analog-to-digital converter, electrically connected to the second N-bit analog-to-digital converter (ADCs), used for converting the second unsigned signal to a second signed signal (Q i );
a digital automatic gain control (AGC) module, electrically connected to the first analog-to-digital converters and the second analog-to-digital converter, used for providing an automatic gain control (AGC) gain setting; and
a baseband demodulator processor, electrically connected to the first analog-to-digital converter and the second analog-to-digital converter, used for processing the first signed signal (I i ) and the second signed signal (Q i ) and providing a demodulated signal;
wherein the digital automatic gain control (AGC) module further comprises:
a power detector, electrically connected to the first analog-to-digital converter and the second analog-to-digital converter, used for providing a plurality of measured power (P i ) evaluated using a plurality of M pairs of sum of squares of the first signed signal (I i ) and the second signed signal (Q i ) where M is an integer from 1 to 100;
a statistics-aided AGC algorithm unit, electrically connected to the first analog-to-digital converter, the second analog-to-digital converter and the power detector, used for determining an additional AGC gain adjustment (Δ Aided ) according to the first signed signal (I i ), the second signed (Q i ) and the plurality of measured power (P i ) and providing the additional AGC gain adjustment (Δ Aided ) according to a power statistic and a amplitude statistic;
a subtractor, electrically connected to the power detector, used for evaluating a power differences between a desired received signal power (P D ) and each of the plurality of measured power (P i ) and providing a plurality of AGC power error signals;
an average unit, electrically connected to the subtractor, used for averaging the plurality of AGC power error signals and providing an average AGC power error signal;
an adder, electrically connected to the average unit and the statistics-aided AGC algorithm unit, used for providing a gain adjustment by adding the additional AGC gain adjustment (Δ Aided ) to the average AGC power error signal;
a multiplier, electrically connected to the adder, used for controlling a AGC loop gain by an adjustable gain (k);
an accumulator, electrically connected to the multiplier, used for tracking the history of accumulations of the average AGC power error signal and providing an appropriate digital gain value (G linear ); and
a LNA and VGA control mapping unit, electrically connected to the accumulator, used for converting the appropriate digital gain value (G linear ) into a LNA and VGA gain control signal.
10. The wireless communication receiver with an automatic gain control (AGC) as claimed in claim 9 , wherein the RF receiver further comprises:
a plurality of stages of low noise amplifier (LNAs), electrically connected to the antenna switch, used for amplifying the RF signal;
a first plurality of variable gain amplifiers (VGAs), electrically connected to the plurality of stages of low noise amplifier (LNAs) through a first filter and a first mixer, used for providing a first signal; and
a second plurality of variable gain amplifiers (VGAs), electrically connected to the plurality of stages of low noise amplifier (LNAs) through a second filter and a second mixer, used for providing a second signal.
11. The wireless communication receiver with an automatic gain control (AGC) as claimed in claim 9 , wherein the accumulator further comprises:
an adder, electrically connected to the multiplier; and
a delay, having an input terminal electrically connected to the adder and an output terminal electrically connected to the adder and the LNA and VGA control mapping unit.