CN103095232A - Dual slope logarithmic amplifier circuit structure - Google Patents

Abstract

The invention relates to a dual slope logarithmic amplifier circuit structure, and belongs to the technical field of circuit structures. The dual slope logarithmic amplifier circuit structure comprises an operational amplifier and two groups of audion pairs. The two groups of audion pairs are respectively switched in a feedback loop and an output loop of the operational amplifier. Input voltage of the operational amplifier is output voltage of a wave detector. First constant current source current and second constant current source current are respectively switched in the two groups of audion pairs. Therefore, when the wave detector works on a square-law area and a linear area, the output voltage of the dual slope logarithmic amplifier circuit structure is directly proportional to signal power of the output voltage of the wave detector, and thus accuracy and linearity of output power are greatly improved. The dual slope logarithmic amplifier circuit structure is simple in structure, low in cost, and also wide in application range.

Description

Dual slope logarithmic amplifier electric line structure

Technical field

The present invention relates to the circuit structure technical field, particularly the amplifier circuit technical field of structures, specifically refer to a kind of dual slope logarithmic amplifier electric line structure.

Background technology

In the electronic equipment with signal generation and output, in order to guarantee the accuracy of output signal power, usually can utilize the ALC(automatic electric-level to control) technology.Signal power is generally unit with dBm.Adopt detector diode as wave detector in the ALC loop, the detecting circuit of wave detector output and the non-linear relation of power take dBm as unit.In order to obtain best software and hardware compensation effect, improve power accuracy and linearity index, usually to first carry out logarithmic amplification to detecting circuit, thereby make through logarithmic amplification later detecting circuit and power (take dBm as unit) linearly, then carry out software and hardware compensation.

The diode detection characteristic has two kinds of working methods: at small power electric at ordinary times, detector diode is operated in " square-law region ", output voltage be proportional to input voltage square, namely be proportional to input power (take mW as unit); At large power, electrically at ordinary times, detector diode is operated in " range of linearity ", and output voltage is proportional to input voltage, namely is proportional to the square root of input power.The detection characteristic curve of detector diode as shown in Figure 1.

Tradition single-slope logarithmic amplifier circuit block diagram as shown in Figure 2.I _inWith input voltage V _inLinear, triode Q ₁Be junction voltage V _be1With I _inBecome logarithmic relationship, triode Q ₂Be junction voltage V _be2With I _oBecome logarithmic relationship, V _out=V _be2-V _be1Can obtain V _outWith V _inRelation: V _out=-V _TLn(V _in/ I _o/ R _in).V in formula _TBe the temperature voltage equivalent, when normal temperature 300K, V _T≈ 26mV.According to the principle of difference channel, utilize two identical triodes of characteristic to compensate, cancellation triode emitter inverse saturation current I _sImpact on operation relation.When detector diode is operated in different qualities when zone, the single-slope amplifier can't be realized the characteristic that the proportionate relationship of output voltage after logarithmic amplification and input signal power is consistent.

Summary of the invention

The objective of the invention is to have overcome above-mentioned shortcoming of the prior art, provide a kind of when detector diode is operated in square-law region and the range of linearity, can realize the linear relationship of output voltage and detection input signal power after logarithmic amplification, thereby significantly improve accuracy and the linearity of power output, and simple in structure, dual slope logarithmic amplifier electric line structure with low cost, as to have wide range of applications.

In order to realize above-mentioned purpose, dual slope logarithmic amplifier electric line structure of the present invention has following formation:

This dual slope logarithmic amplifier electric line structure comprises operational amplifier and two groups of triodes pair, feedback loop and the output loop of described two groups of triodes to accessing respectively described operational amplifier, the input voltage of described operational amplifier is the output voltage of wave detector, the first constant-current source electric current and the second constant-current source electric current access respectively described two groups of triodes pair, when wave detector was operated in square-law region and the range of linearity, the output voltage of this dual slope logarithmic amplifier electric line structure all was directly proportional to signal power from the output voltage of described wave detector.

In this dual slope logarithmic amplifier electric line structure, it is described when wave detector is operated in square-law region, described input voltage is less than or equal to described the first constant-current source electric current, described when wave detector is operated in the range of linearity, described input voltage is during more than or equal to described the first constant-current source electric current.

in this dual slope logarithmic amplifier electric line structure, described two groups of triodes to comprise the feedback loop triode to output loop triode pair, described feedback triode is to comprising NPN triode A and PNP triode A, described output loop triode is to comprising and PNP triode B and NPN triode B, the input voltage of described operational amplifier is connected in the inverting input of this operational amplifier by input resistance, the positive input end grounding of this operational amplifier, the collector electrode of described NPN triode A is connected in the inverting input of described operational amplifier, and the emitter of this NPN triode A connects the emitter of described PNP triode A, the collector electrode of this PNP triode A is connected in described PNP triode B collector electrode, the emitter of this PNP triode B connects the emitter of described NPN triode B, the current collection of described NPN triode B is the output of this dual slope logarithmic amplifier electric line structure very, node between the emitter of the first described NPN triode A of constant-current source electric current access and the emitter of described PNP triode A, node between the emitter of the second constant-current source current Ib 2 described PNP triode B of access and the emitter of described NPN triode B, the first constant-current source electric current equals the second constant-current source electric current, the base earth of described NPN triode A, described PNP triode A, PNP triode B is connected base stage and is all connected separately collector electrode with NPN triode B, the output of described operational amplifier is connected in the collector electrode of described PNP triode A and the node between described PNP triode B collector electrode.

In this dual slope logarithmic amplifier electric line structure, described circuit structure also comprises the voltage bias compensating circuit, described voltage bias compensating circuit is connected in described two groups of triodes pair, in order to realize detection migration, square-law linear compensation and the logarithm offset compensation function for described dual slope logarithmic amplifier electric line structure.

In this dual slope logarithmic amplifier electric line structure, described voltage bias compensating circuit comprises detection bucking voltage output, and described detection bucking voltage output is connected in the inverting input of described operational amplifier by the first resistance.

In this dual slope logarithmic amplifier electric line structure, described voltage bias compensating circuit comprises square-law linearity compensation voltage output end, and described square-law linearity compensation voltage output end is in order to control described the first constant-current source electric current and the second constant-current source electric current.

In this dual slope logarithmic amplifier electric line structure, described voltage bias compensating circuit comprises logarithm bias compensation voltage output, described logarithm bias compensation voltage output is in order to control the constant-current source electric current, the output voltage of described this dual slope logarithmic amplifier electric line structure of described constant-current source electric current access.

adopted the dual slope logarithmic amplifier electric line structure of this invention to comprise operational amplifier and two groups of triodes pair, feedback loop and the output loop of described two groups of triodes to accessing respectively described operational amplifier, the input voltage of described operational amplifier is the output voltage of wave detector, the first constant-current source electric current and the second constant-current source electric current access respectively described two groups of triodes pair, when making wave detector be operated in square-law region and the range of linearity, the output voltage of dual slope logarithmic amplifier electric line structure all is directly proportional to signal power from the output voltage of wave detector, thereby significantly improve accuracy and the linearity of power output, and dual slope logarithmic amplifier electric line structure of the present invention is simple in structure, with low cost, range of application is also comparatively extensive.

Description of drawings

Fig. 1 is the detection characteristic curve chart of detector diode.

Fig. 2 is traditional single-slope logarithmic amplifier circuit block diagram.

Fig. 3 is the schematic diagram of dual slope logarithmic amplifier electric line structure of the present invention.

Fig. 4 is the compensating circuit block diagram of dual slope logarithmic amplifier electric line structure of the present invention.

Embodiment

In order more clearly to understand technology contents of the present invention, describe in detail especially exemplified by following examples.

See also shown in Figure 3ly, be the schematic diagram of dual slope logarithmic amplifier electric line structure of the present invention.

In one embodiment, this dual slope logarithmic amplifier electric line structure comprises operational amplifier and two groups of triodes pair, feedback loop and the output loop of described two groups of triodes to accessing respectively described operational amplifier, the input voltage V of described operational amplifier _inOutput voltage V for wave detector _det, the first constant-current source electric current I _b1With the second constant-current source electric current I _b2Access respectively described two groups of triodes pair, when wave detector is operated in square-law region and the range of linearity, the output voltage V of this dual slope logarithmic amplifier electric line structure _outAll with output voltage V from described wave detector _detSignal power P _dBmBe directly proportional.Described when wave detector is operated in square-law region, described input voltage V _inLess than or equal to described the first constant-current source electric current I _b1, described when wave detector is operated in the range of linearity, described input voltage V _inMore than or equal to described the first constant-current source electric current I _b1The time.

In a kind of more preferably execution mode, described two groups of triodes to comprise the feedback loop triode to output loop triode pair, described feedback triode is to comprising NPN triode A Q _1aWith PNP triode A Q _2aDescribed output loop triode is to comprising the Q with PNP triode B _2bWith NPN triode B Q _1bThe input voltage V of described operational amplifier _inBy input resistance R _inBe connected in the inverting input of this operational amplifier, the positive input end grounding of this operational amplifier, described NPN triode A Q _1aCollector electrode be connected in the inverting input of described operational amplifier, this NPN triode A Q _1aEmitter connect described PNP triode A Q _2aEmitter; This PNP triode A Q _2aCollector electrode be connected in described PNP triode B Q _2bCollector electrode, this PNP triode B Q _2bEmitter connect described NPN triode B Q _1bEmitter, described NPN triode B Q _1bThe current collection output V of this dual slope logarithmic amplifier electric line structure very _out, the first constant-current source electric current I _b1Access described NPN triode A Q _1aEmitter and described PNP triode A Q _2aEmitter between node, the second constant-current source electric current I _b2Access described PNP triode B Q _2bEmitter and described NPN triode B Q _1bEmitter between node, the first constant-current source electric current equals the second constant-current source electric current I _b1=I _b2, described NPN triode A Q _1aBase earth, described PNP triode A Q _2a, PNP triode B Q _2bWith NPN triode B Q _1bBase stage all connect separately collector electrode, the output of described operational amplifier is connected in described PNP triode A Q _2aCollector electrode and described PNP triode B Q _2bNode between collector electrode.

In a kind of preferred execution mode, as shown in Figure 4, described circuit structure also comprises the voltage bias compensating circuit, described voltage bias compensating circuit is connected in described two groups of triodes pair, in order to realize detection migration, square-law linear compensation and the logarithm offset compensation function for described dual slope logarithmic amplifier electric line structure.Described voltage bias compensating circuit comprises detection bucking voltage output V _Detoffset, described detection bucking voltage output V _DetoffsetBy the first resistance R ₁Be connected in the inverting input of described operational amplifier.Described voltage bias compensating circuit comprises square-law linearity compensation voltage output end, and described square-law linearity compensation voltage output end is in order to control described the first constant-current source electric current I _b1With the second constant-current source electric current I _b2Described voltage bias compensating circuit comprises logarithm bias compensation voltage output, and described logarithm bias compensation voltage output is in order to control the constant-current source electric current I _O, described constant-current source electric current I _OAccess the output voltage V of described this dual slope logarithmic amplifier electric line structure _out

In an application of the invention, the solution of circuit structure of the present invention is: comprise integrated operational amplifier, NPN to pipe, PNP to pipe, detection migration, square-law linear compensation and logarithm migration.With feedback loop and the output loop of a pair of NPN triode and a pair of PNP triode access integrated operational amplifier, realize simultaneously single-slope and dual slope logarithmic computing.In the dual slope logarithmic amplifier circuit, two groups of integrated triodes completing the logarithmic amplification function are extremely important to the consistency of pipe.

The present invention compared with prior art, its remarkable advantage is can be by the amplification of diclinic rate, detection migration, square-law linearity compensation and logarithm migration, improves output signal power order of accuarcy and the linearity, good temp characteristic, dynamic range is large.The PNP crystal that the present invention selects a two couplings to the NPN crystal of pipe and a two couplings to managing, have low-down voltage noise, outstanding logarithm consistency, due on the same semiconductor chip with identical technique manufacturing, the Performance Ratio of element is more consistent, and the temperature symmetry is good.

Particularly, V _inBe the wave detector output voltage, the constant-current source electric current I _b1And I _b2Approximately equal.Be that infinitely-great characteristic can obtain triode Q according to the operational amplifier input resistance _1aCollector current:

$I_{1\mathrm{ac}}=I_{\mathrm{in}}=\frac{V_{\mathrm{in}}}{R_{\mathrm{in}}}...\left(1\right)$

Q _2aCollector current:

I _2ac＝I _in+I _b1 ……（2）

Characteristic according to triode:

$I_c=-\mathrm{\α}{I}_e=-\mathrm{\α}{I}_{\mathrm{es}}\left[\exp (q\frac{V_{\mathrm{eb}}}{\mathrm{KT}}-1)\right]...\left(3\right)$

Wherein: I _esEmission current for base stage and collector electrode short circuit;

α is the amplification coefficient of common base direct current;

K=1.38 * 10 ^-23J/K, Boltzmann constant;

Q=1.6 * 10 ^-19C is the charged value in electron institute;

T is absolute temperature (unit K °).

Can obtain triode Q according to formula (3) _1aPressure drop between emitter and base stage is:

$V_{1\mathrm{aeb}}=V_T\ln (-\frac{I_{\mathrm{ac}}}{{\mathrm{\α}}_{1a}\×I_{1\mathrm{aes}}}+1)=V_T\ln (-\frac{I_{\mathrm{in}}}{{\mathrm{\α}}_{1a}\×I_{1\mathrm{aes}}}+1)...\left(4\right)$

Due to Q _1aBase earth, V _1abBe 0, therefore:

$V_{1\mathrm{ae}}=V_{1\mathrm{aeb}}+V_{1\mathrm{ab}}=V_{1\mathrm{aeb}}=V_T\ln (-\frac{I_{\mathrm{in}}}{{\mathrm{\α}}_{1a}\×I_{1\mathrm{aes}}}+1)...\left(5\right)$

Because triode Q2a does diode use, the electric current of flowing through is:

I _2ac=I _1ae+ I _b1≈ I _1ac+ I _b1=I _in+ I _b1The pressure drop that (6) can obtain between triode Q2a emitter and base stage according to formula (3) is:

$V_{2\mathrm{aeb}}=V_T\ln (-\frac{I_{2\mathrm{ac}}}{{\mathrm{\α}}_{2a}\×I_{2\mathrm{aes}}}+1)\≈V_T\ln (-\frac{I_{\mathrm{in}}+I_{b1}}{{\mathrm{\α}}_{2a}\×I_{2\mathrm{aes}}}+1)...\left(7\right)$

Because triode Q2a base stage is connected with triode Q1a emitter, by formula (5) and (7) as can be known:

$V_{2\mathrm{ae}}=V_{2\mathrm{aeb}}+V_{2\mathrm{ab}}=V_{2\mathrm{aeb}}+V_{1\mathrm{ae}}\≈V_T\ln (-\frac{I_{\mathrm{in}}+I_{b1}}{{\mathrm{\α}}_{2a}\×I_{2\mathrm{aes}}}+1)+V_T\ln (-\frac{I_{\mathrm{in}}}{{\mathrm{\α}}_{1a}\×I_{1\mathrm{aes}}}+1)...\left(8\right)$

During small-power, I _in≤ I _b1, I _in+ I _b1≈ I _b1, wave detector is operated in " square-law region ", V _in∝ P _mW,

$V_{2\mathrm{ae}}\≈V_T\ln (-\frac{I_{\mathrm{in}}+I_{b1}}{{\mathrm{\α}}_{2a}\×I_{2\mathrm{aes}}}+1)+V_T\ln (-\frac{I_{\mathrm{in}}}{{\mathrm{\α}}_{1a}\×I_{1\mathrm{aes}}}+1)\∝V_T\ln \left(I_{\mathrm{in}}\right)=V_T\ln \left(\frac{V_{\mathrm{in}}}{R_{\mathrm{in}}}\right)\∝V_T\ln \left(P_{\mathrm{mW}}\right)...\left(9\right)$

When high-power, I _in〉=I _b1, I _in+ I _b1≈ I _in, wave detector is operated in " range of linearity ", V _in ²∝ P _mW,

$V_{2\mathrm{ae}}\≈V_T\ln (-\frac{I_{\mathrm{in}}}{{\mathrm{\α}}_{2a}\×I_{2\mathrm{aes}}}+1)+V_T\ln (-\frac{I_{\mathrm{in}}}{{\mathrm{\α}}_{1a}\×I_{1\mathrm{aes}}}+1)\∝V_T\ln \left(I_{\mathrm{in}}\right)+V_T\ln \left(I_{\mathrm{in}}\right)=V_T\ln {\left(\frac{V_{\mathrm{in}}}{R_{\mathrm{in}}}\right)}^2\∝V_T\ln \left(P_{\mathrm{mW}}\right)...\left(10\right)$

Due to P _dBm=10logP _mW, Q _1bWith Q _2bAs diode use, and current constant is constant, and tube voltage drop is invariable.Therefore no matter input signal is small-power or high-power, and detecting circuit is directly proportional to input signal power (take dBm as unit) all the time through output voltage after dual slope logarithmic amplifying circuit:

V _out∝V _2ae∝V _Tln(P _mW)=V _TP _dBm ……（11）

When detector diode is operated in " range of linearity ", the logarithm conversion gain is the twice of detector diode when being operated in " square-law region ".The logarithm of the signal power (take mW as unit) on having guaranteed the detecting circuit exported after the logarithmic amplification in the double gain of " linear zone " and being input to detector diode all is directly proportional in whole working range.Namely in " range of linearity " and " square-law region " of detector diode whole working range, detecting circuit is all linear through output voltage and power (take dbm as unit) after dual slope logarithmic amplifying circuit.

In order further to improve the linear relationship of detection output voltage and input source signal power, improve the linearity and the accuracy of ALC loop power output, the present invention has designed detection migration, square-law linear compensation and logarithm offset compensation function, utilizes hardware voltage offset electric circuit and software voltage correction-compensation to adjust the operating state of logarithmic amplifier.Voltage offset electric circuit adopts 8 A/D converters of a slice four-way, realizes simultaneously detection migration, square-law linear compensation and the output of logarithm migration bias voltage.The compensating circuit block diagram as shown in Figure 4.

Detection migration principle:

Detecting circuit V _det=V _in, the detection bucking voltage is V _Detoffset, triode Q _1aCollector current be:

$I_{1\mathrm{ac}}=\frac{V_{\det }}{R_{\mathrm{in}}}+\frac{V_{\det \mathrm{offset}}}{R_1}=I_{1\mathrm{as}}\left[\exp (-\frac{V_{1\mathrm{abe}}}{V_T}-1)\right]...\left(12\right)$

$V_{1\mathrm{ae}}=V_T\ln [(\frac{V_{\det }}{R_{\mathrm{in}}}+\frac{V_{\det \mathrm{offset}}}{R_1})/I_{1\mathrm{as}}-1]...\left(13\right)$

Because there is an I in dynatron performance _sSide-play amount, triode c electrode current and its base-emitter voltage V _beBe not strict exponential relationship, introduce the detection offset compensation voltage in the present invention's design, utilize software that bias voltage is set and compensate, when

V _Detoffset/ R ₁/ I _1as=1, i.e. V _Detoffset=R ₁* I _1asThe time, just can eliminate the side-play amount I in dynatron performance _s, make triode V _1aeVoltage become strict logarithmic relationship with the detecting circuit of the c utmost point.Formula (13) can obtain following formula after compensating through detection skew software and hardware:

$V_{1\mathrm{ae}}=V_T\ln (V_{\det }/R_{\mathrm{in}}/I_{1\mathrm{as}})=V_T\ln \left(\frac{I_{\det }}{I_{\mathrm{as}}}\right)...\left(14\right)$

The square-law linearity and logarithm migration principle:

Ignoring the pressure drop of triode base resistance, and thinking in the situation of triode common-base circuit amplification coefficient α ≈ 1,

I _1ac≈ I _1ae, triode Q _2aDo diode use, so Q _2aCollector current is:

$I_{2\mathrm{ac}}=I_{2\mathrm{ae}}=I_{1\mathrm{ae}}+I_{b1}\≈I_{1\mathrm{ac}}+I_{b1}=I_{\det }+I_{b1}=I_{2\mathrm{as}}\exp \left(\frac{V_{2\mathrm{abe}}-1}{V_T}\right)...\left(15\right)$

$V_{2\mathrm{abe}}=V_T\ln (\frac{I_{\det }+I_{b1}}{I_{2\mathrm{as}}}-1)\≈V_T\ln \left(\frac{I_{\det }+I_{b1}}{I_{2\mathrm{as}}}\right)...\left(16\right)$

$V_{2\mathrm{ab}}=V_T\ln (\frac{I_{\det }}{I_{1\mathrm{as}}}\×\frac{I_{\det }+I_{b1}}{I_{2\mathrm{as}}})...\left(17\right)$

In like manner can get:

$V_{2\mathrm{abbe}}=V_T\ln \left(\frac{I_{b2}+I_O}{I_{2\mathrm{as}}}\right)...\left(18\right)$

$V_{1\mathrm{bbe}}=-V_T\ln \left(\frac{I_O}{I_{1\mathrm{bs}}}\right)...\left(19\right)$

So:

$V_{\mathrm{out}}=V_{2\mathrm{ab}}-V_{2\mathrm{abbe}}+V_{1\mathrm{bbe}}=V_T\ln (\frac{I_{\det }}{I_{1\mathrm{as}}}\×\frac{I_{\det }+I_{b1}}{I_{2\mathrm{as}}})-V_T\ln \left(\frac{I_{b2}+I_O}{I_{2\mathrm{as}}}\right)+V_T\ln \left(\frac{I_O}{I_{1\mathrm{bs}}}\right)$

$V_{\mathrm{out}}=V_T\ln (\frac{I_{\det }}{I_{1\mathrm{as}}}\×\frac{I_{\det }+I_{b1}}{I_{2\mathrm{as}}}\×\frac{I_{2\mathrm{bs}}}{I_{b2+I_O}}\×\frac{I_{1\mathrm{bs}}}{I_O})...\left(20\right)$

Q _1aAnd Q _1b, Q _2aAnd Q _2bBe respectively that chip is integrated to pipe, have the characteristics such as electrical performance indexes, distributed constant, physical dimension be consistent, so I _1as=I _1bs, I _2as=I _abs, formula (20) can further be reduced to:

$V_{\mathrm{out}}=V_T\ln (\frac{I_{\det }}{I_O}\×\frac{I_{\det }+I_{b1}}{I_{b2}+I_O})...\left(21\right)$

Employing can be eliminated I to pipe _1as, I _1bs, I _2as, I _absThese 4 parameters relevant with temperature have certain temperature compensation function.

When changing in wider scope along with signal source power, adjust current source I by square-law linearity compensation voltage ₁And I ₂Size, adjust current source I by the logarithm offset compensation voltage _oSize, the output voltage that satisfies under different capacity is all linear.

At the input small power electric at ordinary times, by adjusting the size of square-law linearity compensation voltage, make I _b1〉=I _detRelation is set up, I _detVariation to Q _2aThe impact of work can be ignored, and adjusts simultaneously the size of logarithm offset compensation voltage, makes I _o≤ I _b2, I _b1=I _b2, just can obtain the result of formula (9) this moment, and when having realized the signal source small-power, the final output voltage of detector diode is directly proportional to input power.

At the input large power, electrically at ordinary times, by adjusting the size of square-law linearity compensation voltage, make I _b1≤ I _detRelation is set up, I _b1To Q _2aThe impact of work can be ignored, and adjusts simultaneously the size of logarithm offset compensation voltage, makes I _o〉=I _b2, just can obtain the result of formula (10) this moment, and when having realized that signal source is high-power, the final output voltage of detector diode is directly proportional to input power.So just reached no matter wave detector is operated in " range of linearity " still " square-law region ", all linear with input signal power by output voltage after the dual slope logarithmic amplifier.

adopted the dual slope logarithmic amplifier electric line structure of this invention to comprise operational amplifier and two groups of triodes pair, feedback loop and the output loop of described two groups of triodes to accessing respectively described operational amplifier, the input voltage of described operational amplifier is the output voltage of wave detector, the first constant-current source electric current and the second constant-current source electric current access respectively described two groups of triodes pair, when making wave detector be operated in square-law region and the range of linearity, the output voltage of dual slope logarithmic amplifier electric line structure all is directly proportional to signal power from the output voltage of wave detector, thereby significantly improve accuracy and the linearity of power output, and dual slope logarithmic amplifier electric line structure of the present invention is simple in structure, with low cost, range of application is also comparatively extensive.

In this specification, the present invention is described with reference to its specific embodiment.But, still can make various modifications and conversion obviously and not deviate from the spirit and scope of the present invention.Therefore, specification and accompanying drawing are regarded in an illustrative, rather than a restrictive.

Claims (7)

1. dual slope logarithmic amplifier electric line structure, it is characterized in that, described circuit structure comprises operational amplifier and two groups of triodes pair, feedback loop and the output loop of described two groups of triodes to accessing respectively described operational amplifier, the input voltage (V of described operational amplifier _in) be the output voltage (V of wave detector _det), the first constant-current source electric current (I _b1) and the second constant-current source electric current (I _b2) access respectively described two groups of triodes pair, when wave detector is operated in square-law region and the range of linearity, the output voltage (V of this dual slope logarithmic amplifier electric line structure _out) all with output voltage (V from described wave detector _det) signal power (P _dBm) be directly proportional.

2. dual slope logarithmic amplifier electric line structure according to claim 1, is characterized in that, and is described when wave detector is operated in square-law region, described input voltage (V _in) less than or equal to described the first constant-current source electric current (I _b1), described when wave detector is operated in the range of linearity, described input voltage (V _in) more than or equal to described the first constant-current source electric current (I _b1) time.

3. dual slope logarithmic amplifier electric line structure according to claim 2, is characterized in that, described two groups of triodes to comprise the feedback loop triode to output loop triode pair, described feedback triode is to comprising NPN triode A(Q _1a) and PNP triode A(Q _2a); Described output loop triode is to comprising and PNP triode B(Q _2b) and NPN triode B(Q _1b); Input voltage (the V of described operational amplifier _in) by input resistance (R _in) be connected in the inverting input of this operational amplifier, the positive input end grounding of this operational amplifier, described NPN triode A(Q _1a) collector electrode be connected in the inverting input of described operational amplifier, this NPN triode A(Q _1a) emitter connect described PNP triode A(Q _2a) emitter; This PNP triode A(Q _2a) collector electrode be connected in described PNP triode B(Q _2b) collector electrode, this PNP triode B(Q _2b) emitter connect described NPN triode B(Q _1b) emitter, described NPN triode B(Q _1b) the current collection output (V of this dual slope logarithmic amplifier electric line structure very _out), the first constant-current source electric current (I _b1) the described NPN triode A(Q of access _1a) emitter and described PNP triode A(Q _2a) emitter between node, the second constant-current source electric current (I _b2) the described PNP triode B(Q of access _2b) emitter and described NPN triode B(Q _1b) emitter between node, the first constant-current source electric current equals the second constant-current source electric current (I _b1=I _b2), described NPN triode A(Q _1a) base earth, described PNP triode A(Q _2a), PNP triode B(Q _2b) and NPN triode B(Q _1b) base stage all connect separately collector electrode, the output of described operational amplifier is connected in described PNP triode A(Q _2a) collector electrode and described PNP triode B(Q _2b) node between collector electrode.

4. the described dual slope logarithmic amplifier electric of any one line structure according to claim 1 to 3, it is characterized in that, described circuit structure also comprises the voltage bias compensating circuit, described voltage bias compensating circuit is connected in described two groups of triodes pair, in order to realize detection migration, square-law linear compensation and the logarithm offset compensation function for described dual slope logarithmic amplifier electric line structure.

5. dual slope logarithmic amplifier electric line structure according to claim 4, is characterized in that, described voltage bias compensating circuit comprises detection bucking voltage output (V _Detoffset), described detection bucking voltage output (V _Detoffset) by the first resistance (R ₁) be connected in the inverting input of described operational amplifier.

6. dual slope logarithmic amplifier electric line structure according to claim 4, it is characterized in that, described voltage bias compensating circuit comprises square-law linearity compensation voltage output end, and described square-law linearity compensation voltage output end is in order to control described the first constant-current source electric current (I _b1) and the second constant-current source electric current (I _b2).

7. dual slope logarithmic amplifier electric line structure according to claim 4, is characterized in that, described voltage bias compensating circuit comprises logarithm bias compensation voltage output, and described logarithm bias compensation voltage output is in order to control constant-current source electric current (I _O), described constant-current source electric current (I _O) access described this dual slope logarithmic amplifier electric line structure output voltage (V _out).

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