KR100738397B1 - Automatic gain control device - Google Patents

Abstract

An AGC apparatus is provided to reduce power consumption and obtain an RSSI(Received Signal Strength Indication) value through simple calculation. The first amplifier(31) amplifies a received analog input signal. A frequency converter(32) converts the amplified input signal into an RF(Intermediate Frequency) or BB(BaseBand) signal, and outputs it. A signal detecting circuit(33) detects voltage value of the input signal outputted from the frequency converter(32), compares the voltage value with a pre-set reference voltage, and outputs a digital comparison result as a digital value. The second amplifier(34) amplifies the input signal outputted from the frequency converter(32). An A/D converter(35) converts the amplified input signal into a digital signal and outputs it. An AGC(36) receives the signal outputted from the signal detecting circuit(33) and the signal outputted from the A/C converter, controls gain of the second amplifier(34), and calculates an RSSI value.

Description

Automatic gain control device {AUTOMATIC GAIN CONTROL DEVICE}

1 is a block diagram of an automatic gain control apparatus using a conventional RSSI circuit,

2 is a configuration diagram of an RSSI circuit used in FIG. 1;

3 is a block diagram of an automatic gain control apparatus according to an embodiment of the present invention;

4 is a configuration diagram of a signal detection circuit used in FIG.

* Description of Major Symbols in Drawings *

31: first amplifier 32: frequency converter

33: signal detection circuit 34: second amplifier

35: A / D Converter 36: Auto Gain Controller

41: detectors 42a and 42b: comparators

The present invention relates to an automatic gain control device, and more particularly, by using a signal detection circuit that can be implemented with only a small number of elements instead of the conventional RSSI circuit, the complexity and area can be reduced, and power consumption can be reduced. The present invention relates to an automatic gain control device suitable for a compact, low power wireless communication system.

As part of the demand for the ubiquitous era, researches on wireless LAN (WLAN), wireless personal area network (WPAN), sensor network, and radio frequency identification (RFID) are not in progress. It is becoming. Among the wireless communication systems, the WPAN or sensor network field requires very small size, low cost, and low power consumption as well as communication performance.

Conventional automatic gain control devices used in wireless communication systems are largely divided into analog, analog and digital mixing, and digital, and are used differently depending on the required performance, but the most commonly used methods are analog and digital mixing. That's the way.

Analog-to-digital automatic gain control system mainly uses analog RSSI (Received Signal Strength Indicator) circuit to increase stability and gain control speed, but the circuit area is increased because many amplifiers and additional circuits are used to increase precision and accuracy. And power consumption is increased.

FIG. 1 is a block diagram of an automatic gain control apparatus using a conventional RSSI circuit, and FIG. 2 is a block diagram of an RSSI circuit used in FIG.

As shown in FIG. 1, the conventional automatic gain control apparatus includes a first amplifier 11, a frequency converter 12, an RSSI circuit 13, a second amplifier 14, an A / D converter 15, and an automatic controller. A gain controller 16 is included.

Here, the first amplifier 11 amplifies the analog input signal received through the antenna as a low noise amplifier, and the frequency converter 12 receives the input signal amplified by the first amplifier 11. Converts to an intermediate frequency signal IF or a baseband signal and outputs the converted signal.

In addition, the RSSI circuit 13 detects the voltage value of the input signal output from the frequency converter 12 and compares the voltage value with a preset reference voltage, and digitizes the comparison result to the auto gain controller 16. 2, the RSSI circuit 13 includes a plurality of amplifiers 13a, a detector 13b, and a comparator 13c. The operation principle is briefly described with reference to FIGS. 1 and 2 as follows.

When an input signal output from the frequency converter 12 is applied to the RSSI circuit 13, the signal is detected by a detector and a voltage value detected by the detector by a comparator. The reference voltage level Vref is compared and its output is determined to be 1 or 0 according to the comparison result. Each time through the amplifiers with fixed gain in the same way, the output voltage of each amplifier is digitized through the detector and the comparator so that its output is determined to be 1 or 0.

Therefore, when the size of the input signal applied to the RSSI circuit 13 is very small, the input signal before passing through the plurality of amplifiers 13a becomes smaller than the reference voltage Vref level, so that the output of the comparator is zero. .

Therefore, the voltage value of the input signal becomes larger than the reference voltage Vref level of the comparator only when the input signal is sufficiently amplified through the plurality of amplifiers 13a. At this time, the output of the comparator becomes 1.

Accordingly, as shown in FIG. 2, the output of the comparator at the far right end of FIG. 2 will be 1, and the output of the remaining comparators will be zero.

On the other hand, if the magnitude of the input signal applied to the RSSI circuit 13 is very large, the voltage value detected by the detector from the first comparator 1 becomes larger than the reference voltage Vref level, so that the output of the first comparator becomes 1, Thereafter, the voltage values detected by the plurality of amplifiers 13a will continue to be amplified, so the output values of all comparators will be one.

That is, once a comparator outputs a value of 1 at a point, subsequent comparators receive a signal through the amplifier, so that the outputs of all comparators become 1.

Based on this operation, when a wide dynamic range and precise RSSI values are required, the fixed gain of the amplifier 13a is designed to be small, and the sum of the fixed gains of the amplifier 13a corresponds to the entire dynamic range. What is necessary is just to increase the number of 13a), the detector 13b, and the comparator 13c.

Meanwhile, the second amplifier 14 amplifies an input signal output from the frequency converter 12 as a programmable gain amplifier, and the A / D converter 15 is the second amplifier 14. Converts the input signal amplified by digital signal to output.

In addition, the automatic gain controller 16 receives a signal output from the RSSI circuit 13 and a signal output from the A / D converter 15 and uses the first amplifier 11 and the second amplifier using the same. The gain of (14) is controlled, which is briefly described with reference to FIG. 1 as follows.

The automatic gain controller 16 is a gain setting value of the first and second amplifiers 11 and 14 through which digital data about the magnitude of the current input signal measured by the RSSI circuit 13 and the current input signal pass. Calculate the approximate level of the input signal currently received by the antenna, and reset the gains of the first and second amplifiers 11 and 14 at regular intervals so as to correspond to the calculated values. Through this process, it is possible to determine the approximate absolute gain values of the first and second amplifiers 11 and 14 at one time, thereby enabling rough gain control at a very high speed.

Thereafter, a pre-designed Automatic Gain Control (AGC) is calculated by calculating the power or voltage of the currently received input signal based on the output data of the A / D converter 15. By precisely adjusting the gains of the first and second amplifiers 11 and 14 according to an algorithm, more accurate gain control can be performed.

However, the conventional automatic gain control device requires a large number of amplifiers, detectors, and comparators due to the use of RSSI circuits, which require a wide dynamic range, and thus require a large number of amplifiers, detectors, and comparators. And low power wireless communication systems.

The present invention has been proposed to solve the above problems, and by using a signal detection circuit that can be implemented with only a small number of elements instead of the conventional RSSI circuit, the complexity and area can be reduced, and power consumption is also greatly reduced. The purpose of the present invention is to provide an automatic gain control device suitable for a compact, low power wireless communication system.

The objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. It will also be appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

Automatic gain control apparatus according to the present invention for achieving the above object comprises a first amplifier for amplifying a received analog input signal; A frequency converter converting the input signal amplified by the first amplifier into an intermediate frequency signal IF or a base band signal and outputting the converted signal; A signal detection circuit comprising a detector and a comparator, detecting a voltage value of an input signal output from the frequency converter, comparing the voltage value with a preset reference voltage, and digitizing and outputting the comparison result; A second amplifier amplifying the input signal output from the frequency converter; An A / D converter converting the input signal amplified by the second amplifier into a digital signal and outputting the digital signal; And an automatic gain controller that receives a signal output from the signal detection circuit and a signal output from the A / D converter, controls gains of the first amplifier and the second amplifier using the same, and calculates an RSSI value. do.

The signal detection circuit may include: a detector for detecting a voltage value of an input signal output from the frequency converter; And a comparator comprising: a comparator for comparing a voltage value of an input signal output from the detector with a preset reference voltage through the comparator, and digitizing the comparison result to output a '0' or '1' value; It is characterized in that the configuration.

In this case, the comparator may be configured with one or more comparators in which reference voltages of different levels are set.

In this case, the comparator outputs '1' when the voltage value of the input signal output from the detector is greater than a preset reference voltage, and when the voltage value of the input signal output from the detector is smaller than a preset reference voltage. It is characterized by outputting 0 '.

The above objects, features, and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be.

In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram of an automatic gain control apparatus according to an embodiment of the present invention, and FIG. 4 is a block diagram of a signal detection circuit used in FIG.

As shown in FIG. 3, the automatic gain control apparatus of the present invention includes a first amplifier 31, a frequency converter 32, a signal detection circuit 33, a second amplifier 34, and an A / D converter 35. The automatic gain controller 36 is included.

Here, the first amplifier 31 amplifies an analog input signal received through an antenna as a low noise amplifier, and the frequency converter 32 converts the input signal amplified by the first amplifier 31 into an intermediate frequency signal IF. ) Or baseband (BB) signal is converted and output.

In addition, the signal detection circuit 31 detects the voltage value of the input signal output from the frequency converter 12 and compares the voltage value with a preset reference voltage, and digitizes the comparison result to the automatic gain controller ( 16, the signal detecting circuit 33 is composed of one detector 41 and the comparator 42, the comparator 42 of different levels The reference voltages Vref1 and Vref2 may be configured with one or more comparators 42a and 42b. In the present embodiment, the comparator 42 includes two comparators 42a and 42b.

In this case, the detector 41 detects the voltage value of the input signal output from the frequency converter 32, and the comparator 42 is output from the detector 41 through the comparators 42a and 42b. The voltage value of the input signal is compared with the preset reference voltages Vref1 and Vref2, and the result of the comparison is digitized to output a value of '0' or '1'.

The operation principle of the signal detection circuit 33 will be briefly described with reference to FIGS. 3 and 4 as follows.

The input signal output from the frequency converter 32 is applied to the signal detection circuit 33.

In the conventional RSSI circuit, a plurality of amplifiers, detectors, and comparators are used to detect signals of very small size and to obtain precise RSSI values. However, in the present invention, the detector 41 and the comparator 42a, A signal that can be detected only with 42b), that is, a signal having a power or voltage level of a predetermined level or more, is detected through the detector 41 and the comparators 42a and 42b. In this case, one or more comparators 42a and 42b having different comparison voltage levels Vref1 and Vref2 may be used to detect signals having a predetermined level or more than a predetermined level of power or voltage in several stages. It can be detected in two steps.

The comparator output signal detected as described above is a digital signal of '0' or '1'. At this time, the comparators 42a and 42b use the reference voltage Vref1, which is a preset voltage value of the input signal output from the detector 41. '1' is greater than Vref2) and '0' is output to the automatic gain controller 36 when the voltage value of the input signal output from the detector 41 is smaller than the preset reference voltages Vref1 and Vref2. .

Meanwhile, the second amplifier 34 amplifies an input signal output from the frequency converter 32 as a variable gain amplifier, and the A / D converter 35 amplifies the input signal amplified by the second amplifier 34. Is converted into a digital signal and output.

The automatic gain controller 36 receives the signal output from the signal detection circuit 33 and the signal output from the A / D converter 35 and uses the first amplifier 31 and the first signal. The gain of the two amplifiers 34 is controlled. The control scheme will be briefly described with reference to FIG. 3 as follows.

In the automatic gain controller 36, gains of the first and second amplifiers 31 and 34 through which digital data on the magnitude of the current input signal output through the signal detection circuit 33 and the current input signal pass. After summarizing the set values, the level of the input signal currently received by the antenna is roughly calculated, and the gains of the first and second amplifiers 31 and 34 are reset at predetermined intervals so as to correspond to the calculated values. Through this process, the approximate absolute gain values of the first and second amplifiers 31 and 34 can be set at a relatively high speed.

Then, the gain of the first and second amplifiers 31 and 34 according to a predesigned AGC algorithm by calculating the power or voltage magnitude of the currently received input signal based on the output data of the A / D converter 35. By precisely adjusting the voltage, relatively accurate gain control can be performed.

In addition, the automatic gain controller 36 may simply calculate the RSSI value, which is conventionally measured through the RSSI circuit, using an AGC algorithm, even without the RSSI circuit.

When gain control of the automatic gain control device is stabilized and the output of the second amplifier 34 reaches a desired target level, the following equation (1) is established.

Input signal power (= RSSI) input to the antenna + current set gain sum of amplifiers = target level

Since the currently set gain sum and target level values of the amplifiers are already known in Equation 1, an RSSI value, which means an RSSI value, may be calculated through a simple calculation.

As described above, the present invention has a merit that the complexity and the area of the present invention are greatly reduced compared to the related art by using the signal detection circuit implemented with only a few elements instead of the conventional RSSI circuit.

Table 1 below is a table comparing the complexity of the conventional RSSI circuit and the signal detection circuit of the present embodiment, and shows a roughly inferred result from typical design results.

As shown in Table 1, the signal detection circuit of the present invention can be seen that the complexity is reduced to about 1/5 or less than the conventional RSSI circuit, and in the case of the analog circuit, the complexity and area are considerably proportional to the area It can also be expected to be reduced to levels below about 1/5.

In addition, the signal detection circuit of the present invention described above does not use an amplifier and is implemented by only a small number of detectors and comparators, and thus, power consumption is greatly reduced compared to the conventional art.

Table 2 below is a table comparing the power consumption of the conventional RSSI circuit and the signal detection circuit of the present embodiment, and similarly to Table 1, the table shows the results inferred from the typical design results.

As shown in Table 2, the power consumption is typically increased in the order of detector <comparator <amplifier. It can be seen that the decrease to about 1/8 or less.

 One preferred embodiment of the present invention described above is disclosed for the purpose of illustration, various substitutions, modifications and Modifications may be made and such substitutions, changes and the like should be regarded as belonging to the following claims.

As described above, the automatic gain control apparatus according to the present invention not only reduces the complexity and the area, but also consumes power by using a signal detection circuit that can be implemented with only a small number of elements instead of the conventional RSSI circuit. It can be greatly reduced, so that it can be used in a small, low power wireless communication system.

In addition, even without the RSSI circuit, the RSSI value can be obtained by a simple operation.

Claims (4)

A first amplifier for amplifying the received analog input signal; A frequency converter converting the input signal amplified by the first amplifier into an intermediate frequency signal IF or a base band signal and outputting the converted signal; A signal detection circuit comprising a detector and a comparator, detecting a voltage value of an input signal output from the frequency converter, comparing the voltage value with a preset reference voltage, and digitizing and outputting the comparison result; A second amplifier amplifying the input signal output from the frequency converter; An A / D converter converting the input signal amplified by the second amplifier into a digital signal and outputting the digital signal; And And an automatic gain controller that receives the signal output from the signal detection circuit and the signal output from the A / D converter, controls gains of the first amplifier and the second amplifier using the same, and calculates an RSSI value. Automatic Gain Control. The method of claim 1, wherein the signal detection circuit, A detector for detecting a voltage value of an input signal output from the frequency converter; And A comparator including a comparator, comparing a voltage value of the input signal output from the detector with a preset reference voltage, and digitizing the comparison result to output a '0' or '1' value; Automatic gain control device, characterized in that. The method of claim 2, wherein the comparison unit, Automatic gain control device, characterized in that composed of one or more comparators having different reference voltages set. The method of claim 3, wherein the comparator, If the voltage value of the input signal output from the detector is greater than the predetermined reference voltage output '1', and if the voltage value of the input signal output from the detector is less than the preset reference voltage outputting '0' Automatic gain control device characterized in that.

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