CN104730300A - Measuring device with ALC - Google Patents
Measuring device with ALC Download PDFInfo
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- CN104730300A CN104730300A CN201310721663.8A CN201310721663A CN104730300A CN 104730300 A CN104730300 A CN 104730300A CN 201310721663 A CN201310721663 A CN 201310721663A CN 104730300 A CN104730300 A CN 104730300A
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Abstract
The invention discloses a measuring device with an ALC. The ALC is characterized in that the input end of a variable attenuation unit is connected with the input end of the ALC, the output end of the variable attenuation unit is connected with a power distribution unit, the first output end of the power distribution unit serves as the output end of the ALC, the second output end of the power distribution unit is connected with the input end of a detector, the detector is connected with the input end of a log amplifier, the log amplifier is connected with the first input end of an addition unit, the second input end of the addition unit is connected with the reference voltage, the output end of the addition unit is connected with the input end of an integrator, the integrator is connected with the input end of a voltage conversion unit, and the voltage conversion unit is connected with the adjusting end of the variable attenuation unit. The log amplifier, the addition unit, the integrator and the voltage conversion unit are achieved through a digital chip, an analog-digital converter is arranged between the detector and the log amplifier, and an analog-digital converter is arranged between the voltage conversion unit and the variable attenuation unit. The temperature stability of the ALC is good.
Description
Technical field
The present invention relates to measurement, technical field of measurement and test, particularly relate to a kind of measurement mechanism with alc circuit.
Background technology
In measurement, field tests, radio-frequency signal source is that the one of frequency microwave worker indispensability measures testing tool.Radio-frequency signal source is a kind of emission of radio frequency signals device, and it can export various frequency, the isoparametric continuous wave radiofrequency signal of amplitude, certainly can also export various modulation signal, as modulation signals such as FM, AM, PM, IQ, Pulse.Amplitude degree of accuracy and the degree of stability of radio-frequency signal source output signal are one of important indicators of radio-frequency signal source, and these indexs are generally realized by alc circuit (Automatic Level Control automatic level control circuit).
Number of patent application be 201210539525.3 Chinese patent application file disclose a kind of principle of radio-frequency signal source 100, in conjunction with reference accompanying drawing 1, radio-frequency signal source 100 mainly comprises the frequency synthesizer circuit 101, automatic level control circuit 102, the stepping attenuator circuit 103 that connect successively.
The Main Function of described frequency synthesizer circuit 101 is radiofrequency signals that the various parameters arranged according to user produce certain frequency (fixed frequency or certain frequency scope), frequency synthesizer circuit 101 has multiple implementation, can be directly be made up of phase-locked loop circuit, and then point/frequency multiplication after can produce the radiofrequency signal of wider frequency range, along with the development of immediate data frequency synthesis technique, adopt DDS signal source (also referred to as direct digital synthesis technique source, or DDFS, Direct Digital Frequency Synthesis) ripe all the more in conjunction with the technology of phase-locked loop circuit, the such as patent No. is the radio-frequency signal source that the United States Patent (USP) " Signalgenerator with directly-extractable DDS signal source " of US8044725 discloses a kind of like this frequency synthesizer 101 and forms.
The Main Function of automatic level control circuit 102 is that the radiofrequency signal that frequency synthesizer circuit 101 produces is stabilized in certain amplitude, realized by mimic channel, number of patent application be 201210530377.9,201210530239.0 Chinese patent application file all disclose a kind of radio-frequency signal source with automatic level control circuit.In conjunction with reference accompanying drawing 2, Fig. 2 shows a kind of circuit theory of automatic level control circuit 102, comprises variable attenuator 201, radio frequency amplifier 203, coupling mechanism 204, resistance 202, wave detector 212, logarithmic amplifier 210, totalizer 209, electric capacity 207, operational amplifier 208, logarithmic amplifier 211, totalizer 206, exponential amplifier 205.
The input end 2A of described variable attenuator 201 accesses the radiofrequency signal of described frequency synthesizer circuit 101 generation, and the described radiofrequency signal of access is decayed, the control of the input signal of the modulated end of pad value (also can be called control end) 2C, the output terminal 2B of variable attenuator 201 exports the stabilization signal after overdamping.Described variable attenuator 201 has multiple implementation, such as number of patent application be 201210530622.6 Chinese patent application file disclose wherein part implementation, variable attenuator 201 is generally be made up of PIN diode.
Described radio frequency amplifier 203 amplifies the signal that described variable attenuator 201 exports, and then exports to described coupling mechanism 204.
Input signal is divided into two-way by coupling mechanism 204, and straight-through port 2F directly exports radiofrequency signal, and portion radio frequency signal is then incorporated into described wave detector 212 by coupling port, and isolated port is then directly by resistance 202 ground connection.The effect of coupling mechanism 204 is when reducing radio frequency effect of signals as far as possible, gets the amplitude information of radiofrequency signal, and coupling mechanism 204 can with replacements such as power dividers.
The signal that the coupling port of coupling mechanism 204 is sent by wave detector 212 carries out detection, gets the amplitude information of signal, generates direct current (or the collimation stream) voltage signal relevant to signal amplitude.
Detecting circuit exponent function relation general with the amplitude (" dB " form) of the signal inputing to wave detector 212, therefore uses logarithmic amplifier 210 by described wave detector voltage and the signal linearization inputing to wave detector 212.
The effect of totalizer 209 is that the voltage signal that exported by logarithmic amplifier 210 and a comparative voltage (being produced by port 2G) are compared, and gets error voltage.
Electric capacity 207 and operational amplifier 208 constitute an integrator, the error voltage that totalizer 209 can produce by integrator carries out integration, signal after integration can directly export to exponential amplifier 205, but modulate (amplitude modulation(PAM)) function owing to also needing to realize AM, therefore also need to arrange totalizer 206, the signal now after integrator integration exports to described totalizer 206.
When needing AM to modulate, user arranges AM and modulates correlation parameter, produce AM modulation signal eventually through port 2H and export to described logarithmic amplifier 211, the effect of logarithmic amplifier 211 is that AM modulation signal is converted to logarithmic form, to coordinate the exponential amplifier 205 of back, correctly described variable attenuator 201 could be driven.The signal that logarithmic amplifier 211 produces exports to described totalizer 209 and totalizer 206 respectively, when AM frequency modulating signal is lower, the normal work of totalizer 209 is given in the signal that logarithmic amplifier 211 exports, totalizer 209 produces error voltage and sends into integrator after rectified signal, reference signal and AM modulation signal are carried out additive operation, now whole circuit can normally work; When AM frequency modulating signal is higher, the normal work of totalizer 206 is given in the signal that logarithmic amplifier 211 exports, integrator output signal is done additive operation with the signal that logarithmic amplifier 211 exports by totalizer 206, then jointly exports to described exponential amplifier 205.
The effect of exponential amplifier 205 is that the linear signal before after logarithmic amplifier conversion is converted to exponential signal again, then described variable attenuator 201 is driven, realize the automatic lever regulation of whole circuit, until the signal stabilization that port 2F exports is in a fixed amplitude.
The effect of step attenuator circuit 103 is Signal Regulation that the frequency that produced by described automatic level control circuit 102 and amplitude are fixed is the amplitude that user needs, the amplitude range that can realize can be marked in the index of general radio-frequency signal source 100, such as generally can realize from-130dBm or lower until the amplitude range of+20dBm or wider, step attenuator circuit 103 is now just needed to regulate, step attenuator circuit 103 is prior aries, and such as number of patent application is that 201210539536.1 Chinese patent application files disclose a kind of implementation.
In addition, for described variable attenuator 201, sometimes also need extra driving circuit to drive, because described variable attenuator 201 generally has PIN diode to form, certain curtage is needed during its work, working current can reach tens milliamperes, and therefore existing driving circuit is generally constant current driving or constant voltage driving.Constant current drives, and is and the damping capacity of variable attenuator 201 demand is converted to corresponding current, produce this steady current and export to the adjustable side of variable attenuator 201, and the voltage of variable attenuator 201 is determined by diode self character by a circuit; Constant voltage drives, and with regard to for the damping capacity of variable attenuator 201 demand is converted to corresponding voltage, produce constant voltage and export to the adjustable side of variable attenuator 201, and the electric current of variable attenuator 201 is determined by diode self character by a circuit.
Because diode itself is easily by influence of temperature change, along with circuit working, when the temperature at this circuit place changes, the diode voltage current relationship of variable attenuator 201 also changes: drive for constant current, the electric current that driving circuit produces remains unchanged, and voltage changes; Drive for constant voltage, the voltage that driving circuit produces remains unchanged, and electric current changes.But comparatively speaking, the temperature stability of the variable attenuator 201 under constant current driving condition drives higher than constant voltage, because the voltage-current relationship of diode can be similar to use following function representation:
In above formula, I
s, V
tfor temperature variant constant; I
snumerical value is less, but varies with temperature scope comparatively large (about 1E-15 ~ 1E-6A).V
twith temperature line relationship (
t is thermodynamic temperature), about 26mV under normal temperature (about 27 DEG C, 300K), variable quantity is relatively little.AC impedance (R
aC) for diode is at the slope at working point place, to above formula differential:
Can find out, when electric current immobilizes, AC impedance is similar to and V
tlinear; When voltage immobilizes, AC impedance becomes complicated relation with temperature, I
schange will cause AC impedance occur very large change.
On the other hand, the attenuator bandwidth under constant current drive pattern is lower than constant voltage drive pattern, and reason is as follows: on the one hand, and the bandwidth of constant-current drive circuit itself limits the bandwidth of attenuator; On the other hand, the driving circuit of constant current mode uses the nonlinear element of triode or diode and so on to build mostly, realize current constant by the method for dynamic adjustments triode or diode resistance, and variable attenuator 201 itself uses PIN diode to build, have larger non-linear.When both conbined usage, the voltage at variable attenuator 201 two ends will there will be serious nonlinearities change, greatly reduce attenuator bandwidth.
Therefore, all there is certain restriction in constant-current drive circuit and constant voltage drive circuit, can not meet the demand of the variable attenuator in measurement mechanism.
By finding out discussion above: existing automatic level control circuit 102 adopts mimic channel to realize, in mimic channel, except variable attenuator 201, wave detector 212 generally adopts outside diode realization (the general detector diode of wave detector 212 realizes), logarithmic amplifier 210 and 211, exponential amplifier 205 grade generally adopts diode and triode to build, diode and triode are temperature-sensing element (device), its circuit characteristic can vary with temperature and change, just make the stability of whole automatic level control circuit 102 not enough, the stability of automatic level control circuit 102 itself only can reduce the impact of operational amplifier 208 circuit below (mainly exponential amplifier 205), and cannot to wave detector 212, logarithmic amplifier 210 and 211 etc. has an impact, if employing temperature compensation, generally in wave detector 212 place set temperature detecting sensor, detect the temperature of the circuit board at wave detector 212 place, then process post-compensation is carried out to the temperature detected, but the impact that logarithmic amplifier 210 and 211 etc. brings cannot be reduced.
And, in described radio-frequency signal source 100, described automatic level control circuit 102 also needs to realize AM modulation function, namely the port 2H in accompanying drawing 2 inputs AM modulation signal, export to totalizer 209 and 206 after being changed by logarithmic amplifier 211, and then drive described variable attenuator 201 to realize AM modulation.In the process, owing to introducing logarithmic amplifier 211, AM can be made to modulate because additionally amplifying and temperature variation and distortion.On the one hand, AM modulation is response speed to variable attenuator 201 major requirement, need the expansion AM modulating frequency upper limit, automatic level control circuit 102 then major requirement itself is amplitude degree of accuracy, to promote the amplitude degree of accuracy of output signal, therefore adopt variable attenuator 201 to realize AM modulation and alc circuit just requires that variable attenuator 201 has very high degree of accuracy and very short response time simultaneously, and the scope of adjustable damping amount is very wide simultaneously.Moreover, AM modulation and alc circuit finally adopt same driving circuit to drive described variable attenuator 201, need described variable attenuator 201 within the scope of very wide damping capacity, also will keep having good linear relationship with control signal, otherwise time different from the power of the radiofrequency signal (i.e. the carrier wave of corresponding A M modulation) of described variable attenuator 201 input end input when driving the voltage of described variable attenuator 201 identical, modulated signal (the signal exported after namely have passed through AM modulation, also the signal of i.e. now variable attenuator 201 output terminal output) will change.Above variety of problems both increases the difficulty of AM modulation function together with alc circuit design, makes whole circuit be difficult to realize.
By discussing above and can drawing, in prior art, there are the following problems:
1, because whole automatic level control circuit adopts mimic channel to realize, temperature has a great impact whole circuit tool, also be difficult to by various means such as temperature compensations the impact eliminating temperature, and then affect amplitude degree of accuracy and the degree of stability of automatic level control circuit;
2, because AM modulation is together with alc circuit design, the design of whole circuit is made to there is difficulty greatly;
3, all there is a definite limitation in the constant current driving of variable attenuator and constant voltage drive pattern, can not meet the demand of the variable attenuator in measurement mechanism.
Summary of the invention
In order to solve exist in background technology adopt mimic channel to realize due to whole automatic level control circuit, and then affect the amplitude degree of accuracy of automatic level control circuit and the problem of degree of stability, the invention provides a kind of amplitude degree of accuracy and the good measurement mechanism with alc circuit of degree of stability.
The invention provides a kind of measurement mechanism with alc circuit, described alc circuit comprises variable attenuation unit, power distributing unit, wave detector, logarithmic amplifier, adder unit, integrator, voltage conversion unit,
The input end that the input end of described variable attenuation unit connects the input end of described alc circuit, output terminal connects described power distributing unit,
First output terminal of described power distributing unit connects the input end of described wave detector as the output terminal of described alc circuit, the second output terminal,
The output terminal of described wave detector connects the input end of described logarithmic amplifier,
The output terminal of described logarithmic amplifier connects the first input end of described adder unit,
The input end that second input end connects a reference voltage, output terminal connects described integrator of described adder unit,
The output terminal of described integrator connects the input end of described voltage conversion unit,
The output terminal of described voltage conversion unit connects the adjustable side of described variable attenuation unit;
Described logarithmic amplifier, adder unit, integrator and voltage conversion unit are realized by a digit chip,
Between the output terminal and the input end of described logarithmic amplifier of described wave detector, be also provided with an analog to digital converter, between the output terminal and the adjustable side of described variable attenuation unit of described voltage conversion unit, be also provided with a digital to analog converter.
In measurement mechanism of the present invention, by the logarithmic amplifier in described alc circuit, adder unit, integrator, voltage conversion unit is all arranged in same digit chip, signal after described detector is undertaken sampling by described analog to digital converter and obtains corresponding digital detection signal, then described logarithmic amplifier can carry out logarithmic amplification process to digital rectified signal, then described adder unit is given, the signal that described logarithmic amplifier exports by described adder unit and described reference signal compare, give described integrator by the error voltage after relatively and carry out integration, and give described voltage conversion unit by the signal after integration and realize voltage transitions, then the digital voltage that voltage conversion unit exports is converted to corresponding analog voltage and gives described variable attenuation unit by described digital to analog converter, to change the pad value of described variable attenuation unit, radiofrequency signal is stabilized in certain amplitude the most at last, due to described logarithmic amplifier, adder unit, integrator, voltage conversion unit is all adopt digital circuit in digit chip, just make these circuit substantially can not be subject to the impact of temperature, and then reduce temperature further to the impact of whole alc circuit, improve degree of accuracy and the degree of stability of variable attenuator in lc circuit.
Illustrate as one, of the present invention have in the measurement mechanism of alc circuit, and described digit chip adopts programmable logic chip to realize.
Illustrate as one, of the present invention have in the measurement mechanism of alc circuit, and described programmable logic chip adopts FPGA type programmable logic chip.
Illustrate as one, of the present invention have in the measurement mechanism of alc circuit, in described digit chip, the first linear amplifier is also connected in series with between described logarithmic amplifier and described adder unit, the signal that logarithmic amplifier produces can be carried out Linear Amplifer, to mate the requirement of subsequent conditioning circuit to signal by the first linear amplifier.
Illustrate as one, of the present invention have in the measurement mechanism of alc circuit, in described digit chip, a holding circuit is connected in series with between described integrator and described voltage conversion unit, described holding circuit comprises first switch element, first register, a state controller, a totalizer, described first switch element connects the output terminal of described integrator and the input end of described first register, the output terminal of described first register connects the first input end of described totalizer, second input end of described totalizer connects a preset voltage, the output terminal of described totalizer connects the input end of described voltage conversion unit, the control signal sensitivity that described switch element produces described state controller, makes the separated of the input end of the output terminal of described integrator and described register.
Illustrate as one, of the present invention have in the measurement mechanism of alc circuit, in described digit chip, also comprise the second linear amplifier, second switch unit, the 3rd switch element, described second switch unit, for selecting, the input end of described logarithmic amplifier with one of described second linear amplifier is connected with the output terminal of described analog to digital converter, described 3rd switch element, is connected described logarithmic amplifier with the input end of described first linear amplifier with the output terminal of one of described second linear amplifier for selecting.
Illustrate as one, of the present invention have in the measurement mechanism of alc circuit, in described digit chip, also comprise the second register, subtracter, described second register, for storing one group of calibration value, described subtracter, after doing subtraction for the signal that exported by described analog to digital converter and described calibration value, operation result is exported to described logarithmic amplifier.
Illustrate as one, of the present invention have in the measurement mechanism of alc circuit, is also connected in series with an attenuator between described power distributing unit and described wave detector.
Illustrate as one, of the present invention have in the measurement mechanism of alc circuit, between described wave detector and described analog to digital converter, be also connected in series with another logarithmic amplifier.
In order to solve exist in background technology due to AM modulation and alc circuit design together with and make the problem of whole circuit design difficulty, the invention provides a kind of radio-frequency signal source with amplitude modulation(PAM) and automatic level control function.
The radio-frequency signal source with amplitude modulation(PAM) and automatic level control function of the present invention, comprises variable attenuation unit, power distributing unit, wave detector, data processing unit, modulation signal generation unit,
Described modulation signal generation unit, for generation of a road am signals,
Described variable attenuation unit, decays to input signal under the driving of drive singal that exports at described data processing unit, produces deamplification,
Described power distributing unit, for described deamplification is divided into two-way: wherein a road directly exports, wave detector is exported on another road,
Described wave detector, for carrying out detection process to the signal of input, obtains rectified signal,
Described data processing unit, for producing described drive singal according to described am signals and described rectified signal,
Described variable attenuation unit comprises the first variable attenuator and the second variable attenuator that are connected in series,
Described data processing unit comprises the first data processing unit and the second data processing unit,
Described first data processing unit, for producing the first drive singal driving described first variable attenuator according to described rectified signal,
Described second data processing unit, for producing the second drive singal driving described second variable attenuator according to described am signals.
Of the present invention have in the radio-frequency signal source of amplitude modulation(PAM) and automatic level control function, variable attenuator in described AM modulation and automatic level control circuit is provided separately, one of them variable attenuator is used for realizing AM modulation, another variable attenuator is used for realizing auto level control, when needs carry out AM modulation, described modulation signal generation unit produces amplitude modulation(PAM) (i.e. AM modulation) signal, described second data processing unit just drives corresponding variable attenuator according to described am signals, to realize AM modulation function, when needs automatic level control circuit works, described wave detector carries out detection to the signal that power distributing unit exports to wave detector, obtain rectified signal and export to the first data processing unit, described first data processing unit normally drives corresponding variable attenuator according to rectified signal, to realize auto level control, due to described amplitude modulation(PAM) and auto level control are provided separately, all components and parts are not needed to take into account the demand of the two, therefore circuit easily realizes.
Illustrate as one, of the present invention have in the radio-frequency signal source of amplitude modulation(PAM) and automatic level control function, and described first data processing unit and the second data processing unit are all be made up of a digit chip; Between described digit chip and described wave detector, be also connected with an analog to digital converter, described analog to digital converter is used for described rectified signal to be converted to digital signal and sends to the first data processing unit in described digit chip; Described first drive singal drives described first variable attenuator by first digital to analog converter; Described second drive singal drives described second variable attenuator by second digital to analog converter.
Illustrate as one, of the present invention have in the radio-frequency signal source of amplitude modulation(PAM) and automatic level control function, and described digit chip is FPGA type programmable logic chip.
Illustrate as one, of the present invention have in the radio-frequency signal source of amplitude modulation(PAM) and automatic level control function, is also connected in series with a radio frequency amplifier between described first variable attenuator and the second variable attenuator.
Illustrate as one, of the present invention have in the radio-frequency signal source of amplitude modulation(PAM) and automatic level control function, and described first variable attenuator is connected in series between described second variable attenuator and described power distributing unit.
Illustrate as one, of the present invention have in the radio-frequency signal source of amplitude modulation(PAM) and automatic level control function, in described digit chip, described first data processing unit comprises: logarithmic amplifier, adder unit, integrator, voltage conversion unit, the input end of described logarithmic amplifier connects the output terminal of described analog to digital converter, the input end of described logarithmic amplifier connects the first input end of described adder unit, second input end of described adder unit connects a reference voltage, output terminal connects the input end of described integrator, the output terminal of described integrator connects the input end of described voltage conversion unit, the output terminal of described voltage conversion unit connects the input end of described first digital to analog converter.
Illustrate as one, of the present invention have in the radio-frequency signal source of amplitude modulation(PAM) and automatic level control function, in described digit chip, a holding circuit is connected in series with between described integrator and described voltage conversion unit, described holding circuit comprises first switch element, first register, a state controller, a totalizer, described first switch element connects the output terminal of described integrator and the input end of described first register, the output terminal of described first register connects the first input end of described totalizer, second input end of described totalizer connects a preset voltage, the output terminal of described totalizer connects the input end of described voltage conversion unit, the control signal sensitivity that described switch element produces described state controller, makes the separated of the input end of the output terminal of described integrator and described register.
Illustrate as one, of the present invention have in the radio-frequency signal source of amplitude modulation(PAM) and automatic level control function, in described digit chip, between described logarithmic amplifier and described adder unit, is also connected in series with the first linear amplifier.
Illustrate as one, of the present invention have in the radio-frequency signal source of amplitude modulation(PAM) and automatic level control function, is also connected in series with an attenuator between described power distributing unit and described wave detector.
Illustrate as one, of the present invention have in the radio-frequency signal source of amplitude modulation(PAM) and automatic level control function, and described modulation signal generation unit adopts dsp chip to form.
In order to the constant current driving and constant voltage drive pattern that solve the variable attenuator existed in background technology all exist restriction, and then the problem of the variable attenuator demand in measurement mechanism can not be met, the invention provides a kind of measurement mechanism driving better effects if.
The measurement mechanism with variable attenuation unit of the present invention, comprises variable attenuation unit, data processing unit,
Described variable attenuation unit, decays to input signal under the driving of a drive singal that exports at described data processing unit, produces deamplification,
Described data processing unit, for generation of described drive singal,
Also comprise a drive singal processing unit, described drive singal processing unit comprises operational amplifier, resistance, adjustable line pad,
The adjustable side of described variable attenuation unit connects the first end of described resistance and the input end in the same way of described operational amplifier respectively,
Second end of described resistance connects the output terminal of described operational amplifier and the output terminal of described adjustable line pad respectively,
The input end of described adjustable line pad connects the output terminal of described data processing unit,
The reverse input end of described operational amplifier connects the adjustment end of described adjustable line pad.
In measurement mechanism of the present invention, by arranging operational amplifier, resistance and adjustable line pad form drive singal processing unit, operationally, adjustable line pad has stablizes adjustable attenuation ratio, they and described variable attenuation unit form one group of electric bridge jointly, by the equivalent resistance regulating the pad value of variable attenuator to realize regulating described variable attenuation unit, and then realize the object of Attenuation adjustable, make the equivalent resistance of described variable attenuation unit only relevant with the resistance of described resistance with the attenuation ratio of described adjustable line pad, (output voltage of described variable attenuation unit compares input voltage finally to make the linear decrement of described variable attenuation unit, be multiplied by 100% again) linear with described adjustable linear attenuator attenuates value, make the equivalent resistance of described variable attenuation unit constant, there is good stability characteristic (quality), higher bandwidth, the good linearity, the demand of measurement mechanism can be met.
Illustrate as one, of the present invention have in the measurement mechanism of variable attenuation unit, and described adjustable line pad adopts R-2R multiplying-type digital to analog converter to realize.
Illustrate as one, of the present invention have in the measurement mechanism of variable attenuation unit, also comprises a dispensing unit, for configuring the code value of described R-2R multiplying-type digital to analog converter according to described drive singal.
Illustrate as one, of the present invention have in the measurement mechanism of variable attenuation unit, and described data processing unit and described dispensing unit are made up of a FPGA type programmable logic chip.
Illustrate as one, of the present invention have in the measurement mechanism of variable attenuation unit, and described adjustable line pad adopts digital regulation resistance to realize.
Accompanying drawing explanation
Fig. 1 is the circuit theory diagrams of radio-frequency signal source 100 of the present invention;
Fig. 2 is the circuit theory diagrams of automatic level control circuit 102 of the present invention;
Fig. 3 is the circuit theory diagrams of alc circuit 300 of the present invention;
Fig. 4 is the another circuit theory diagrams of alc circuit 300 of the present invention;
Fig. 5 is the another circuit theory diagrams of alc circuit 300 of the present invention;
Fig. 6 is the another circuit theory diagrams of alc circuit 300 of the present invention;
Fig. 7 is the another circuit theory diagrams of alc circuit 300 of the present invention;
Fig. 8 is the another circuit theory diagrams of radio-frequency signal source 100 of the present invention;
Fig. 9 is the circuit theory diagrams of measurement mechanism 900 of the present invention;
Figure 10 is a voltage relationship schematic diagram of measurement mechanism 900 of the present invention;
Figure 11 is the damping capacity relation schematic diagram of measurement mechanism 900 of the present invention.
Embodiment
For enabling above-mentioned purpose of the present invention, feature and advantage become apparent more, and below in conjunction with the drawings and specific embodiments, the present invention is further detailed explanation.
In conjunction with reference accompanying drawing 3 and accompanying drawing 4, show a kind of specific embodiment of alc circuit of the present invention (automatic level control circuit) 300, described alc circuit 300 comprises variable attenuation unit 301, power distributing unit 302, wave detector 303, digit chip 304, analog to digital converter 305, digital to analog converter 306, the input end 3A of wherein said variable attenuator 301 is input ends of described alc circuit 300, the output terminal of described variable attenuator 301 then connects the input end of described power distributing unit 302, first output terminal 3B of described power distributing unit 302 is as the output terminal of described alc circuit 300, second output terminal 3C connects the input end of described wave detector 303, the output terminal of described wave detector 303 connects the input end of described analog to digital converter 305, the output terminal of described analog to digital converter 305 connects the input end 3D of described digit chip 304, the output terminal 3E of described digit chip 304 connects the input end of described digital to analog converter 306, the output terminal of described digital to analog converter 306 connects the adjustable side of described variable attenuation unit 301.
Logarithmic amplifier 401 is included in wherein said digit chip 304, adder unit 402, integrator 403, voltage conversion unit 404, the input end of wherein said logarithmic amplifier 401 is connected to the input end 3D of described digit chip 304, output terminal is connected to the first input end of described adder unit 402, second input end of described adder unit 402 connects a reference voltage V1, output terminal is connected to the input end of described integrator 403, the output terminal of described integrator 403 is connected to the input end of described voltage conversion unit 404, the output terminal of described voltage conversion unit 404 is connected to the output terminal 3E of described digit chip 304.
When specific works, input signal is entered by the input end 3A of alc circuit 300, after variable attenuation unit 301 is decayed, export through the first output terminal 3B of described power distributing unit 302 again, now sub-fraction signal is exported to described wave detector 303 by its second output terminal 3C by power distributing unit 302, the signal of wave detector 303 to input carries out detection, obtain direct current (or collimation stream) signal, then the direct current signal that analog to digital converter 305 pairs of wave detectors 303 obtain is sampled, obtain corresponding digital signal and send to the input end 3D of described digit chip 304, in described digit chip 304, first this digital signal is carried out logarithmic amplification by logarithmic amplifier 401, then described adder unit 402 is given, the signal that logarithmic amplifier 401 transports by adder unit 402 and described reference voltage V1 do addition or subtraction, and (doing additive operation is because if the symbol of signal that transports of described reference voltage V1 and described logarithmic amplifier 401 is contrary, need the error voltage that just can obtain between them with additive operation, because if described reference voltage V1 is identical with the symbol of the signal that described logarithmic amplifier 401 transports when doing subtraction, just need to do the error voltage that subtraction just can obtain between them), then the error amount obtained is given described integrator 403 and do integral operation, result after integral operation is converted to after corresponding digital drive voltage through described voltage conversion unit 404, digital to analog converter 306 is given by the output terminal 3E of digit chip 304, the digital signal received is converted to variable attenuation unit 301 described in analog voltage rear drive and decays by digital to analog converter 306, described alc circuit 300 is tended towards stability.
Due to described logarithmic amplifier 401, adder unit 402, integrator 403, voltage conversion unit 404 is all realize in a slice digit chip 304 inside, make their temperature influence very little or influenced by ambient temperature hardly, therefore in whole alc circuit, only need the temperature variation (mainly wave detector 303 brings) to other components and parts bring to carry out temperature compensation, just multiple implementation can be had to the temperature compensation of wave detector 303, constant-temperature circuit is such as set around wave detector 303 to ensure the temperature remained constant around it, or temperature compensation can also be carried out in described digit chip 304, separately a temperature compensation module can be set in described digit chip 304, also temperature compensation can be realized by regulating some reference voltage level of digit chip 304, therefore the temperature compensation of whole alc circuit 300 is relatively easy, the amplitude degree of accuracy of alc circuit 300 and degree of stability are effectively improved.
As explanation, described alc circuit 300 has a lot of application in measurement mechanism, such as can be applied in the automatic level control circuit as radio-frequency signal source 100, also can be applied to as in the local oscillation circuit of spectrum analyzer, calibration source circuit or tracing source circuit.
As explanation, described variable attenuation unit 301 can be made up of a variable attenuator, if when now also needing to realize other functions such as amplitude modulation(PAM), am signals can be carried out disposal route as identical in automatic level control circuit 102, sent into the signal obtained with detection again after carrying out logarithmic amplification in digit chip 304 and carried out additive operation, then jointly driven variable attenuator; Described variable attenuation unit 301 also can be in series by two variable attenuators, if when needing to realize other functions such as amplitude modulation(PAM), can realize differential declines function respectively.
As explanation, described power distributing unit 302 can be realized by the various existing mode such as directional coupler, power distributing circuit.
Illustrate as one, can also arrange as other circuit such as radio frequency amplifier between described variable attenuation unit 301 and power distributing unit 302.
Illustrate as one, described digit chip 304 adopts FPGA type programmable logic chip to realize, and FPGA type programmable logic chip resource is many, low in energy consumption, is applicable to circuit design.
As one distortion, described digit chip 304 can also adopt CPLD type programmable logic chip to realize, and dsp chip can also be adopted to realize, etc.
Illustrate as one, in conjunction with reference accompanying drawing 5, in described digit chip 304, a subtracter 405, register 406 was also set before described logarithmic amplifier 401, one group of calibration value is stored in described register 406, first output terminal of described subtracter connects the input end 3D of described digit chip 304, the second input end connects described register 306, output terminal connects described logarithmic amplifier 401.During work, first can measure and obtain one group of calibration value, this group calibration value can be the radiofrequency signal be input in variable attenuation unit 301 one group of data that is very little or that obtain without measurement during radiofrequency signal, when practical application, first the digital signal that analog to digital converter 305 inputs through port 3D is deducted described calibration data, to reduce the error that alc circuit 300 itself brings.
Illustrate as another, in conjunction with reference accompanying drawing 5, a linear amplifier 407 can also be arranged in parallel with described logarithmic amplifier 401, and be provided with two switch elements 408 and 409, described switch element 408 and 409 can be either-or switch, described switch element 408 is arranged on the output terminal of described subtracter 405 and described to amplifier 401, (if there is no described subtracter 405 between the input end of linear amplifier 407, so just be arranged on port 3D and described to amplifier 401, between the input end of linear amplifier 407), switch element 409 is arranged on described to amplifier 401, between the output terminal of linear amplifier 407 and the input end of described adder unit 402.Described switch element 408 can select the signal that subtracter 405 exports to give logarithmic amplifier 401 or linear amplifier 407, and described switch element 409 can select in described logarithmic amplifier 401 or linear amplifier 407 to output signal to described adder unit 402.Such setting be because sometimes alc circuit 300 export signal amplitude with " volt (V) " for the voltage of the proportional change of unit or rectified signal have passed through logarithmic amplification, and not needing to carry out logarithmic amplification, the signal now transported through port 3D can carry out amplification process through described linear amplifier 407.
As one distortion, described linear amplifier 407 can be also through path, and does not amplify.
Illustrate as another, in conjunction with reference accompanying drawing 5, if there is no switch element 409 at described switch element 409(, be exactly so logarithmic amplifier 401) and described adder unit 402 between be also provided with a linear amplifier 410, the signal that logarithmic amplifier 401 or linear amplifier 407 are sent here can be carried out Linear Amplifer by linear amplifier 410 again, to mate circuit such as subsequent integration device 403 grade.
Illustrate as another, continue to combine with reference to accompanying drawing 5, a holding circuit 411 is also provided with between described integrator 403 and voltage conversion unit 404, in conjunction with reference accompanying drawing 6, described holding circuit 411 includes switch 415, register 412, state controller 414, totalizer 413, one end of described switch 415 connects the output terminal of described integrator 403, the other end connects the input end of described register 412, the control end of switch 415 connects described state controller 414, the output terminal of described register 412 connects the input end of described totalizer 413, the other end of described totalizer 413 connects a prevalue voltage module 416, described preset voltage module 416 can produce a preset voltage, the output terminal of described totalizer 413 connects the input end of described voltage conversion unit 404.
The state that described holding circuit 411 can realize alc circuit 300 keeps.When normally working, state controller 414 controls described switch 415 and closes, the signal that integration produces constantly is sent to described register 412 by integrator 403, register 412 real-time update, obtain driving voltage after the signal that described register 412 exports by totalizer 413 and described preset voltage carry out additive operation, and send to described voltage conversion unit to change, when needing alc circuit 300 to be in hold mode, (now alc circuit 300 only remains on same state according to certain damping capacity, and do not need feedback regulation variable attenuation unit 301), state controller 414 controls described switch 415 and disconnects, now register 412 does not upgrade, data in register 412 are data of the last transmission before switch 415 disconnects, after this register 412 continues these data constantly to send to totalizer 413, totalizer 413 sends to voltage conversion unit 404 to carry out voltage transitions again after these data and preset voltage are done addition, now voltage is a fixed value, then described variable attenuation unit 301 is driven to keep decay according to same pad value by digital to analog converter 306, if mimic channel realizes this function, due to a period of time that analogue integrator sends to the data of totalizer or exponential amplifier can only keep very short, be difficult to make alc circuit 300 remain on certain state always.The amplitude output signal linear correlation of described preset voltage and alc circuit 300, can be converted to described preset voltage, also can directly directly be configured by digit chip 304 by the signal that analog to digital converter 305 produces.
Illustrate as one, in conjunction with reference accompanying drawing 7, in described digit chip 304, described integrator 403 is generally realized by totalizer 417, before described totalizer 417, be generally also provided with linear amplifier 418 error voltage that adder unit 402 exports is amplified, then send to totalizer 417 to carry out accumulation calculating, cumulative result is the output signal of integrator 403.
Illustrate as one, described logarithmic amplifier 401 generally adopts dual slope logarithmic amplifier, and dual slope logarithmic amplifier can represent with following formula:
y＝K*(ln(x)+ln(x+A))+B
Wherein, x is input, and y is for exporting, and K, A, B are constant.
And the effect of described voltage conversion unit 404 to input to linearization between the voltage of voltage conversion unit 404 and the damping capacity of variable attenuation unit 301, corresponding to described logarithmic amplifier 401, voltage conversion unit can adopt exponential amplifier to realize, and the mode of wave table value also can be adopted directly to realize.Suppose that the relation between the control voltage of variable attenuation unit 301 and its damping capacity uses following function representation:
yATT=f (x), the funtcional relationship between the constrained input voltage of so voltage conversion unit 404 with
yATTinverse function f
-1x () is linear, accurately can realize the wave table configuration of voltage conversion unit 404.
Illustrate as one, an attenuator can also be set between described power distributing unit 302 and described wave detector 303, described attenuator can regulate the RF signal power entering wave detector 303 further, wave detector 303 and power distributing unit 302 can also be isolated, the mutual interference of both reductions.
Illustrate as one, a logarithmic amplifier is also connected in series with between described wave detector 303 and described analog to digital converter 305, the amplitude range that logarithmic amplifier can further expand the radiofrequency signal that can lock of alc circuit 300 is set herein, reduce the requirement to analog to digital converter 305, but can temperature stability be affected.
Present embodiments provide a kind of measurement mechanism with alc circuit, by the logarithmic amplifier in described alc circuit, adder unit, integrator, voltage conversion unit etc. are arranged in same digit chip, to replace mimic channel, and then make in whole alc circuit by the components and parts of influence of temperature change be reduced to only have wave detector etc. a few, and wave detector can realize compensating by the method for temperature compensation, thus whole alc circuit temperature influence is reduced, enhance degree of stability and the degree of accuracy of alc circuit.
As other embodiment, when described alc circuit 300 is applied in radio-frequency signal source 100, described radio-frequency signal source 100 also needs to realize AM modulation (amplitude modulation(PAM) function), in conjunction with reference accompanying drawing 8, fig. 8 illustrate a kind of new circuit theory of radio-frequency signal source 100, the automatic level control circuit 102 of described radio-frequency signal source 100 comprises variable attenuator 801 and 805, power distributing unit 802, wave detector 803, data processing unit 804 and 807, modulation signal generation unit 806.
Wherein, described variable attenuator 805, variable attenuator 801 and power distributing unit 802 are sequentially connected in series between the input port 8A and output port 8B of described automatic level control circuit 102, described variable attenuator 801, power distributing unit 802, wave detector 803 and data processing unit 804 together constitute alc circuit, this alc circuit can adopt the implementation as alc circuit 300, to realize auto level control, owing to having discussed the various implementations of alc circuit 300 above in detail, repeated no more herein.
Described variable attenuator 805 is then for realizing amplitude modulation(PAM), and wherein said modulation signal generation unit 806, for generation of am signals, may be used for realizing the functions such as internal modulation, external modulation or inside and outside hybrid modulation, therefore has multiple implementation.Such as, described modulation signal generation unit 806 can be realized by dsp chip, user arranges amplitude modulation(PAM) correlation function and parameter by keyboard, then by dsp chip, the information that user is arranged is resolved, and sending to data processing unit 807, the function that user directly arranges by described data processing unit 807 and parameter are converted into the drive singal driving variable attenuator 805.
Be out of shape as one, described modulation signal generation unit 806 can also be have the realizations such as host computer, user utilizes host computer amplitude modulation(PAM) function to be opened and parameters, and the function that user arranges by data processing unit 807 and parameter are converted into the drive singal driving variable attenuator 805.
As another distortion, described modulation signal generation unit 806 also can be jointly be made up of the mimic channel and voltage transformation module that arrange generation modulation signal according to user, the information that the mimic channel producing modulation signal is arranged according to user produces corresponding simulating signal, then voltage transformation module controls variable attenuator after changing again, realizes amplitude modulation(PAM).
As another distortion, described modulation signal generation unit 806 can also receive external modulation signal, then utilize analog to digital converter to sample and obtain corresponding digital modulation signals, and then utilize as FPGA type programmable logic chip etc. processes digital modulation signals, again through digital-to-analog conversion rear drive variable attenuator, realize amplitude modulation(PAM).
In the present embodiment, described data processing unit 807 and data processing unit 804 adopt same FPGA type programmable logic chip to realize, certainly now described data processing unit 804 both sides are also provided with analog to digital converter and digital to analog converter, the output terminal of described data processing unit 807 is also provided with digital to analog converter, such scheme can economize on resources, and FPGA type programmable logic chip has rich in natural resources carrys out Parallel Implementation two kinds of functions.
As one distortion, described data processing unit 807 can adopt independent FPGA type programmable logic chip to realize, or adopts the realization such as dsp chip or ARM chip.
As one distortion, the position of described variable attenuator 805 and 801 can exchange.
As one distortion, between described variable attenuator 805 and 801, radio frequency amplifier can also be provided with, to reduce the signal-to-noise ratio degradation problem of the radiofrequency signal caused due to the attenuator series connection of larger damping capacity.
Be out of shape as one, variable attenuator 801 in the present embodiment, power distributing unit 802, wave detector 803 and data processing unit 804 together constitute alc circuit, described alc circuit also can not adopt the implementation as alc circuit 300, and adopt the scheme of the simulation alc circuit as shown in accompanying drawing 2, equally by amplitude modulation(PAM) and auto level control separately design, make the design of whole circuit also relatively easy, but simulation alc circuit exists the problem of easy temperature influence equally, effect is not as adopting the scheme of digit chip better.
The radio-frequency signal source that the present embodiment is discussed, by amplitude modulation(PAM) and auto level control two kinds of functions being provided separately, controlling different variable attenuators respectively, reduces the difficulty that radio-frequency signal source realizes amplitude modulation(PAM) function and automatic level control function.
Because variable attenuator generally also needs driving circuit to drive, as other embodiment, a kind of measurement mechanism 900 with variable attenuation unit is discussed further below in conjunction with accompanying drawing 9, comprise variable attenuation unit 901, operational amplifier 902, adjustable line pad 903, resistance 904, data processing unit 905, wherein operational amplifier 902, adjustable line pad 903 and resistance 904 together constitute drive singal processing unit.
Described variable attenuation unit 901 can be the variable attenuator realizing amplitude modulation(PAM), or realizes the variable attenuator of auto level control, etc.Described variable attenuation unit 901 for decaying to the signal that input end 9A inputs under the driving of a drive singal of described data processing unit 905 output, and produce deamplification and exported by output terminal 9B, drive singal is inputted by port 9C.
Described data processing unit 905 can be the am signals generation unit realizing amplitude modulation(PAM), for producing corresponding am signals according to arranging of user; Or realize the circuit of auto level control, for producing corresponding feedback control signal according to the voltage obtained from output port 9B detection, etc.
The adjustable side 9C of described variable attenuation unit 901 connects the first end of described resistance 904 and the input end in the same way of described operational amplifier 902 respectively, second end of described resistance 904 connects the output terminal of described operational amplifier 902 and the output terminal 9F of described adjustable line pad 903 respectively, the input end of described adjustable line pad 903 connects the output terminal of described data processing unit 905, and the reverse input end of described operational amplifier 902 connects the adjustment end 9E of described adjustable line pad 903.In addition, the power end 9D of described operational amplifier 902 connects a power supply, earth terminal ground connection.
During specific works, adjustable line pad 903, resistance 904 and variable attenuation unit 901 together constitute an electric bridge.If the output end voltage of operational amplifier 902 is Vo, also namely the voltage at the output terminal 9F place of described adjustable line pad 903 is Vo; The voltage of the adjustment end 9E of adjustable line pad 903 is Vr, and the voltage of the common port (i.e. the adjustable side of variable attenuation units 901) of resistance 904 and variable attenuation unit 901 is Vd.
The relation of the voltage Vr of the voltage Vo of the output terminal 9F of so adjustable line pad 903 and its adjustment end 9E is as curve Vr1 and Vr2 in accompanying drawing 10, two straight lines from initial point 0, the different different intrinsic standoff ratios representing adjustable line pad 903 of the slope of curve Vr1 with Vr2.And the relation of the input voltage Vo of the bleeder circuit that resistance 904 and variable attenuation unit 901 form and the voltage Vd of its adjustable side 9C is as the curve Vd1 in accompanying drawing 10, curve Vd1 is one and crosses the logarithmic curve of initial point 0, and the intersection point of curve Vr1, Vr2 and curve Vd1 is the working point that whole circuit normally works.
When described adjustable line pad 903 is operated in the state of curve Vr1, S1 point can be operated in after last whole circuit stability, now the input end in the same way of operational amplifier 902 is equal with the voltage of reverse input end, i.e. Vd=Vr=Vd1, the output end voltage Vo=Vo1 of operational amplifier 902.In like manner, when changing the state of described adjustable line pad 903, when making it be operated in the state of curve Vr2, working point can respond and move to a S2, now the input end in the same way of operational amplifier 902 is equal with reverse input end voltage, i.e. Vd=Vr=Vd2, the output end voltage Vo=Vo2 of operational amplifier 902.
If the attenuation ratio of described adjustable line pad 903 is a, that is:
The resistance of resistance 904 is R
0, the equivalent resistance of variable attenuation unit 901 is R
d, so can obtain:
According to discussion above, as Vr=Vd after whole circuit stability, obtain further:
Therefore, can find out when whole circuit working is stablized, the equivalent resistance Rd of described variable attenuation unit 901 is values relevant to the attenuation ratio of adjustable line pad 903, can regulate by regulating the attenuation ratio of adjustable line pad 903, and then realize the object of variable attenuation unit 901 differential declines amount.
Illustrate as one, described adjustable line pad 903 adopts R-2R multiplying-type digital to analog converter to realize, R-2R multiplying-type digital to analog converter is that (bandwidth index weighted-voltage D/A converter realizes the bandwidth of multiplication for a kind of adjustable line pad of broader bandwidth, be not the bandwidth of itself), make the bandwidth of whole circuit also wider, described R-2R multiplying-type digital to analog converter configures its code value by dispensing unit, different attenuation ratios can be realized, the voltage of the reference input (the output terminal 9F of corresponding adjustable line pad 903) of R-2R multiplying-type digital to analog converter is Vo, the voltage of output terminal (the adjustable side 9E of corresponding adjustable line pad 903) is Vr, if the number of significant digit of R-2R multiplying-type digital to analog converter is L position, code value is D, the span of D is [0, 2
l-1), so:
And then can obtain:
When after whole circuit stability, the equivalent resistance of described variable attenuation unit 901 is:
Namely due to resistance R
0fixing, the number of significant digit L of R-2R multiplying-type digital to analog converter fixes, and changes its code value D by dispensing unit, can realize the corresponding equivalent resistance changing described variable attenuation unit 901.
The relatively difference that drives of the driving circuit of the present embodiment and constant current driving and constant voltage, in conjunction with reference accompanying drawing 11, figure 11 show three kinds of differences driven, wherein horizontal ordinate is the code value D of R-2R multiplying-type digital to analog converter, the ratio of ordinate to be the linear decrement ATT_lin(computing method of variable attenuation unit 901 the be voltage of the output terminal 9B of variable attenuation unit 901 and the voltage of input end 9A, then be multiplied by 100%), unit is %, span is [0,100].Wherein curve X1 is constant voltage relation curve, and curve X2 is the circuit curve of the present embodiment, and curve X3 is constant current relation curve, obviously can find out that the curve of the present embodiment is more close to linear relationship, is easy to accurate adjustment.
As one distortion, described adjustable line pad 903 can also adopt the realization such as digital regulation resistance or simulation potentiometer, also can realize the object of the present embodiment.But R-2R multiplying-type digital to analog converter is more easy to configuration, regulates more accurately, and degree of accuracy is higher, be specially adapted to adopt digit chip to produce in the measurement mechanism driving variable attenuation unit.
Illustrate as one, data processing unit 905 in the present embodiment and dispensing unit can be realized by a FPGA type programmable logic chip, such as the driving circuit in the present embodiment is applied to as in alc circuit 300, FPGA type programmable logic chip described in a slice can be adopted to realize numerous function.
As one distortion, the data processing unit 905 in the present embodiment and dispensing unit can be realized by independent digit chip, as dsp chip, ARM chip etc., also by same a slice as realizations such as dsp chip, ARM chips, can have multiple implementation.
Present embodiments provide a kind of driving circuit of variable attenuator, forming electric bridge by arranging adjustable line pad, operational amplifier and resistance, because resistance during electric bridge stabilizing is determined, making the equivalent resistance of variable attenuator relatively stable; Because the temperature influences such as adjustable line pad, resistance are relatively little, make whole driving circuit temperature influence relatively little, temperature stability is relatively high; And there is the good linearity, the demand of variable attenuator in measurement mechanism can be met.
Above embodiment is to illustrate the invention and not to limit the present invention, this area general technology people according to above-mentioned design philosophy do any not creative creation, all should be considered as within the protection domain of this patent.
Claims (9)
1. have a measurement mechanism for alc circuit, described alc circuit comprises variable attenuation unit, power distributing unit, wave detector, logarithmic amplifier, adder unit, integrator, voltage conversion unit,
The input end that the input end of described variable attenuation unit connects the input end of described alc circuit, output terminal connects described power distributing unit,
First output terminal of described power distributing unit connects the input end of described wave detector as the output terminal of described alc circuit, the second output terminal,
The output terminal of described wave detector connects the input end of described logarithmic amplifier,
The output terminal of described logarithmic amplifier connects the first input end of described adder unit,
The input end that second input end connects a reference voltage, output terminal connects described integrator of described adder unit,
The output terminal of described integrator connects the input end of described voltage conversion unit,
The output terminal of described voltage conversion unit connects the adjustable side of described variable attenuation unit;
It is characterized in that:
Described logarithmic amplifier, adder unit, integrator and voltage conversion unit are realized by a digit chip,
Between the output terminal and the input end of described logarithmic amplifier of described wave detector, be also provided with an analog to digital converter, between the output terminal and the adjustable side of described variable attenuation unit of described voltage conversion unit, be also provided with a digital to analog converter.
2. a kind of measurement mechanism with alc circuit according to claim 1, is characterized in that:
Described digit chip adopts programmable logic chip to realize.
3. a kind of measurement mechanism with alc circuit according to claim 2, is characterized in that:
Described programmable logic chip adopts FPGA type programmable logic chip.
4. a kind of measurement mechanism with alc circuit according to claim 1,2 or 3, is characterized in that:
In described digit chip, between described logarithmic amplifier and described adder unit, be also connected in series with the first linear amplifier.
5. a kind of measurement mechanism with alc circuit according to claim 1,2 or 3, is characterized in that:
In described digit chip, between described integrator and described voltage conversion unit, be connected in series with a holding circuit,
Described holding circuit comprises first switch element, first register, state controller, a totalizer, described first switch element connects the output terminal of described integrator and the input end of described first register, the output terminal of described first register connects the first input end of described totalizer, second input end of described totalizer connects a preset voltage, and the output terminal of described totalizer connects the input end of described voltage conversion unit;
The control signal sensitivity that described switch element produces described state controller, makes the separated of the input end of the output terminal of described integrator and described register.
6. a kind of measurement mechanism with alc circuit according to claim 4, is characterized in that:
In described digit chip, also comprise the second linear amplifier, second switch unit, the 3rd switch element,
Described second switch unit, is connected the input end of described logarithmic amplifier with one of described second linear amplifier with the output terminal of described analog to digital converter for selecting,
Described 3rd switch element, is connected described logarithmic amplifier with the input end of described first linear amplifier with the output terminal of one of described second linear amplifier for selecting.
7. a kind of measurement mechanism with alc circuit according to claim 1,2 or 3, is characterized in that:
In described digit chip, also comprise the second register, subtracter,
Described second register, for storing one group of calibration value,
Described subtracter, after doing subtraction, exports to described logarithmic amplifier by operation result for the signal that exported by described analog to digital converter and described calibration value.
8. a kind of measurement mechanism with alc circuit according to claim 1,2 or 3, is characterized in that:
An attenuator is also connected in series with between described power distributing unit and described wave detector.
9. a kind of measurement mechanism with alc circuit according to claim 6, is characterized in that:
Another logarithmic amplifier is also connected in series with between described wave detector and described analog to digital converter.
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