The utility model content
The purpose of this utility model is to provide a kind of automatic gain control equipment of permanent envelope receiver, so that receiver need not to adjust ring in the digitally controlled variable gain, greatly reduces the complexity of automatic gain control, has promoted the speed of automatic gain control.
For solving the problems of the technologies described above, execution mode of the present utility model provides a kind of automatic gain control equipment of permanent envelope receiver, comprises: low noise amplifier LNA, radio-frequency (RF) mixer MIXER, programmable gain amplifier PGA, limiting amplifier, automatic gain controller AGC and radio frequency peak detector;
Described radio frequency peak detector detects the input signal strength of described LNA, and exports to described AGC;
Described limiting amplifier calculates the intensity indication RSSI that receives signal, and exports to described AGC;
Described AGC, according to from the input signal strength of described radio frequency peak detector with from the RSSI of described limiting amplifier, adjust the yield value of described permanent envelope receiver, until that described input signal strength does not occur is saturated, and described RSSI does not reach the maximum that described limiting amplifier can be indicated, and described RSSI is not lower than the minimum value that described limiting amplifier can be indicated; Wherein, described permanent envelope receiver yield value be the yield value sum of low noise amplifier LNA, radio-frequency (RF) mixer MIXER, programmable gain amplifier PGA and limiting amplifier; The yield value of described limiting amplifier is fixed value;
Wherein, described AGC occurs saturated at described input signal strength, when perhaps described RSSI reaches the maximum that described limiting amplifier can indicate, reduces value with what the yield value reduction of described permanent envelope receiver was preset; Do not occur saturatedly at described input signal strength, and described RSSI is when being lower than the minimum value that described limiting amplifier can indicate, and the yield value of described permanent envelope receiver is increased default added value.
The utility model execution mode in terms of existing technologies, adopt the limiting amplifier of current gain value, according to the input signal strength of low noise amplifier with from the intensity indication RSSI of the reception signal of limiting amplifier, adjust low noise amplifier, the yield value of radio-frequency (RF) mixer or programmable gain amplifier, until that input signal strength does not occur is saturated, and the intensity indication that receives signal does not reach the maximum that limiting amplifier can be indicated, and when the intensity indication that receives signal is not lower than the minimum value that limiting amplifier can indicate, finish automatic gain control, enter accepting state.In automatic gain control process, need not to adjust ring in the digitally controlled variable gain, greatly reduce the complexity of automatic gain control, promoted the speed of automatic gain control.
In addition, described radio frequency peak detector comprises the first radio frequency peak detector and the second radio frequency peak detector;
Described the first radio frequency peak detector detects the input signal strength of described LNA;
Described the second radio frequency peak detector detects the input signal strength of described MIXER;
Described AGC input signal strength saturated or described MIXER occurs at the input signal strength of described LNA and occurs judging that described input signal strength occurs saturated when saturated; The input signal strength that saturated and described MIXER do not occur at the input signal strength of described LNA does not occur judging that described input signal strength does not occur saturated when saturated.
By adopting two radio frequency peak detectors to detect simultaneously the input signal strength of low noise amplifier and radio-frequency (RF) mixer, even corresponding radio-frequency input signals is different in the time of can guaranteeing that low noise amplifier reaches capacity with radio-frequency (RF) mixer, both can be unsaturated yet.
In addition, before carrying out automatic gain control, described AGC also arranges described default added value and the described default value that reduces; Wherein, described default added value and described default reducing are worth with the yield value of described limiting amplifier and cooperate, and produce a slow zone, can guarantee that AGC (automatic gain control) system can not enter unhelpful concussion state; In addition, described default added value and described default reducing are worth the yield value that is less than or equal to described limiting amplifier; And the size in slow zone as required determines added value and reduce value, to guarantee to produce slow zone.
In addition, before carrying out automatic gain control, the yield value that described LNA, described MIXER and described PGA arrange separately is maxgain value.
Be in the maximum gain state by the initial state that makes receiver, can so that in the situation that the reception signal is little, the yield value of receiver just needn't be adjusted can carry out follow-up demodulation, have further promoted the speed of automatic gain control.
Embodiment
For making the purpose of this utility model, technical scheme and advantage clearer, below in conjunction with accompanying drawing each execution mode of the present utility model is explained in detail.Yet, persons of ordinary skill in the art may appreciate that in each execution mode of the utility model, in order to make the reader understand the application better many ins and outs have been proposed.But, even without these ins and outs with based on many variations and the modification of following each execution mode, also can realize each claim of the application technical scheme required for protection.
The utility model the first execution mode relates to a kind of automatic gain control equipment of permanent envelope receiver, as shown in Figure 2, be the framework of whole receiver shown in the figure, comprise: low noise amplifier LNA, radio-frequency (RF) mixer MIXER, programmable gain amplifier PGA, limiting amplifier, automatic gain controller AGC and radio frequency peak detector.
Wherein, the radio frequency peak detector detects the input signal strength of LNA, and exports to AGC, when input signal is too large, causes the fast reducing gain of AGC system, and is saturated to avoid the RF front end to occur.
Limiting amplifier is amplified to certain intensity with filtered signal, and the yield value of this limiting amplifier is fixed value.This moment, signal consisted predominantly of the information of using, because be constant enveloped modulation, just can remove incoherent amplitude information through limited range enlargement, and not affect phase information.The output of limiting amplifier can be used for the demodulation of base-band information, and limiting amplifier also calculates the intensity indication RSSI that receives signal simultaneously, and exports to AGC.For example, limiting amplifier can be divided into six output detections points of Pyatyi, when output corresponding to certain point exceeds certain threshold value, is output as 1, otherwise is zero.Therefore, when input signal reaches the maximum that limiting amplifier can indicate, be output as 111111, when input signal is lower than the minimum value that limiting amplifier can indicate, be output as 000000.Intermediateness can be 011111,001111,000111,000011,000001 etc.In addition, it will be understood by those skilled in the art that the intensity of the reception signal that provides is designated as discrete signal herein, also can export with continuous signal the intensity of index signal.
Automatic gain controller AGC, according to from the input signal strength of radio frequency peak detector with from the RSSI of limiting amplifier, adjust the yield value of permanent envelope receiver, until that input signal strength does not occur is saturated, and RSSI does not reach the maximum that limiting amplifier can be indicated, and RSSI is not lower than the minimum value that limiting amplifier can be indicated; Wherein, AGC occurs saturated at input signal strength, when perhaps RSSI reaches the maximum that limiting amplifier can indicate, reduces value with what the yield value reduction of permanent envelope receiver was preset; Do not occur saturatedly at input signal strength, and RSSI is when being lower than the minimum value that limiting amplifier can indicate, and the yield value of permanent envelope receiver is increased default added value.
The yield value of permanent envelope receiver is the yield value sum of low noise amplifier LNA, radio-frequency (RF) mixer MIXER, programmable gain amplifier PGA and limiting amplifier; The yield value of limiting amplifier is fixed value, the yield value of LNA, MIXER and PGA is adjustable, therefore, can reach by the yield value of adjusting LNA, MIXER or PGA the purpose of the yield value of adjusting permanent envelope receiver, specifically, if increase the yield value of LNA, MIXER or PGA, then the yield value of permanent envelope receiver increases; If reduce the yield value of LNA, MIXER or PGA, then the yield value of permanent envelope receiver reduces.
In addition, it is worth mentioning that, AGC also arranges default added value and the default value that reduces, by rational added value with reduce value, cooperate the current gain value of limiting amplifier, can produce a slow zone, guarantee that the AGC system can not enter unhelpful concussion state.In addition, default added value and default reduce to be worth the yield value that is less than or equal to limiting amplifier; And the size in slow zone as required determines added value and reduce value, to guarantee to produce slow zone.
Compared with prior art, present embodiment adopts the limiting amplifier of current gain value, according to the input signal strength of low noise amplifier with from the intensity indication RSSI of the reception signal of limiting amplifier, adjust low noise amplifier, the yield value of radio-frequency (RF) mixer or programmable gain amplifier, until that input signal strength does not occur is saturated, and the intensity indication that receives signal does not reach the maximum that limiting amplifier can be indicated, and when the intensity indication that receives signal is not lower than the minimum value that limiting amplifier can indicate, finish automatic gain control, enter accepting state.In automatic gain control process, need not to adjust ring in the digitally controlled variable gain, greatly reduce the complexity of automatic gain control, promoted the speed of automatic gain control.
The utility model the second execution mode relates to a kind of automatic gain control equipment of permanent envelope receiver.The second execution mode and the first execution mode are roughly the same, main distinction part is: in the first embodiment, according to the intensity indication of the reception signal of the input signal strength of low noise amplifier and limiting amplifier output, adjust the yield value of permanent envelope receiver.And in the utility model the second execution mode, according to the input signal strength of low noise amplifier, the input signal strength of radio-frequency (RF) mixer and the intensity indication of the reception signal that limiting amplifier is exported, adjust the yield value of permanent envelope receiver.
Specifically, as shown in Figure 3, can utilize two radio frequency peak detectors: the first radio frequency peak detector and the second radio frequency peak detector, detect respectively the input signal strength of low noise amplifier LNA and the input signal strength of radio-frequency (RF) mixer MIXER; Correspondingly, AGC is judging whether input signal strength occurs doing corresponding adjustment when saturated, namely input signal strength saturated or MIXER occurs at the input signal strength of LNA and occurs judging that input signal strength occurs saturated when saturated; Do not occur saturatedly at the input signal strength of LNA, and the input signal strength of MIXER does not occur judging that input signal strength does not occur saturated when saturated.
By adopting two radio frequency peak detectors to detect simultaneously the input signal strength of low noise amplifier and radio-frequency (RF) mixer, even corresponding radio-frequency input signals is different in the time of can guaranteeing that low noise amplifier reaches capacity with radio-frequency (RF) mixer, both can be unsaturated yet.Need to prove, described herein is a kind of implementation.For industry technical staff, above realization can be amplified and only use one of them peak detector.For example, if the non-linear behaviour of low noise amplifier and radio-frequency (RF) mixer is subject to radio-frequency (RF) mixer, then can only detects the input signal strength of frequency mixer, and process accordingly; Vice versa.
In addition, in the situation of the structure that does not change the first execution mode or the second execution mode, before carrying out automatic gain control, the yield value that LNA, MIXER and PGA can arrange separately is maxgain value, and namely permanent envelope receiver initial state always is in maximum gain.Be in the maximum gain state by the initial state that makes receiver, can so that in the situation that the reception signal is little, the yield value of receiver just needn't be adjusted can carry out follow-up demodulation, have further promoted the speed of automatic gain control.
Because the yield value of LNA, MIXER and PGA all is adjustable, therefore, according to the intensity indication that receives signal, when adjusting the yield value of permanent envelope receiver, can adjust one or several the yield value among LNA, MIXER and the PGA.Such as in carrying out the yield value adjustment process of permanent envelope receiver, AGC is for the first time to judge that input signal strength occurs saturated, when perhaps RSSI reaches the maximum that limiting amplifier can indicate, reduces value with what the yield value reduction of LNA was preset; For the second time to judge that input signal strength occurs saturated, when perhaps RSSI reaches the maximum that limiting amplifier can indicate, reduce value with what the yield value reduction of LNA and PGA was preset; When for the first time judging that RSSI is lower than the minimum value that limiting amplifier can indicate, the added value that the yield value increase of LNA is preset; For the second time judging that RSSI is lower than the minimum value that limiting amplifier can be indicated, then the yield value with LNA and PGA increases default added value.
Seeing also shown in Figure 4 is a kind of receiver state transition diagram that adopts present embodiment.Because the gain of whole receiving terminal comprises the variable gain of LNA, MIXER and PGA, also comprise the fixed gain of limiting amplifier, therefore, to be in the maximum gain state be the state that the yield value of LNA, MIXER and PGA is set to maxgain value in the permanent envelope receiver to permanent envelope receiver; The second gain-state is that the yield value of LNA reduces the default value (such as the 30dB among Fig. 4) that reduces than maximum, and the yield value of MIXER and PGA is the state of maxgain value; The 3rd gain-state is that the yield value of LNA and PGA reduces the default value that reduces than maximum, and the yield value of MIXER is the state of maxgain value.
Permanent envelope receiver initial state always is in maximum gain, such as when permanent envelope receiver start, the yield value of LNA, MIXER and PGA is set to maxgain value.If detect the RF front end this moment full (being that the input signal strength appearance is saturated) or the input of limiting amplifier excessive (being that RSSI reaches the maximum that limiting amplifier can be indicated) are arranged, yield value has a large reduction, such as, providing example among the figure is 30dB, but can adjust in the real system.Under the second gain-state, the RF front end is saturated or the limiting amplifier input is excessive if still detect, and yield value further reduces, and arrives the 3rd gain-state (being lowest gain state).Otherwise limiting amplifier was inputted low (being that RSSI is lower than the minimum value that limiting amplifier can be indicated) if receiver is not at the maximum gain state, and the RF front end does not have saturated, and AGC adjusts can increase system gain.As shown in Figure 4, on the contrary from be up to least gain or, can two the step in adjust to the right place.
In addition, if each overstriding of adjusting might make the signal to noise ratio of system be reduced to the scope that can not receive, if this restriction appears in the parameter of receiver, also can add into a stage gain adjustment with identical principle, realize automatic gain control.
Fig. 5 has provided a scheme result who follows the two-stage AGC adjustment of Fig. 4 logical design, can find out that the gain control manufacture-illegal of system is often simple.In addition, two curves have been provided among the figure, the 501st, the adjustment curve when input signal increases, suppose herein, the gain ranging of limiting amplifier is 40dB, when input signal by-100 decibels of millivolts (dBm) be increased to-during 60dBm, the RSSI of limiting amplifier indication maximum, the yield value of receiver reduces 30dB; When input signal be increased to-during 30dBm, maximum is indicated in the RSSI of limiting amplifier indication again, the yield value of receiver reduces 30dB again.502 is input signal adjustment curves when reducing among the figure, when input signal be reduced to respectively-40dBm and-during 70dBm, the RSSI indication of limiting amplifier reaches minimum value, the yield value of receiver is corresponding increase 30dB all.Can find out, by default added value and the default value that reduces rationally are set, cooperate the current gain value of limiting amplifier, just can produce a slow zone, be shown as 10dB in Fig. 5 example, this can guarantee that the AGC system can not enter unhelpful concussion state.
In the present embodiment, be in the maximum gain state by the initial state that makes receiver, can be so that in the situation that the reception signal is little, the yield value of receiver just needn't be adjusted can carry out follow-up demodulation.According to principle of the present utility model, though initial state not at the maximum gain state, system also can carry out correct gain adjustment; But as a rule, the maximum gain state is the state that the most easily occurs, and when especially receiver was in always listening state, initial state was arranged at the maximum gain state, can reduce unnecessary adjustment.
Persons of ordinary skill in the art may appreciate that the respective embodiments described above are to realize specific embodiment of the utility model, and in actual applications, can do various changes to it in the form and details, and do not depart from spirit and scope of the present utility model.