CN105207630A - Transconductance amplifier structure achieving high linearity through current reuse - Google Patents

Abstract

The invention provides a transconductance amplifier structure achieving high linearity through current reuse. The transconductance amplifier structure is suitable for serving as a radio frequency transconductance stage of a lower frequency mixer in a wireless receiving link, and comprises an asymmetric differential pair and a pair of common source amplification stages formed by a bias transistor and a resonance circuit. Compared with a traditional five-tube differential pair amplification structure, under the same bias current, the asymmetric differential pair can obtain better linearity. In the common source amplification stages, the tail current bias transistor of the differential pair serves as an additional amplification device, the total transconductance value is increased under the premise that the bias current is not increased, and the utilization rate of the bias current is increased. Compared with a traditional structure, the transconductance amplifier structure is improved in the aspects of linearity and the utilization rate of the bias current.

Description

A kind of trsanscondutance amplifier structure of current multiplexing high linearity

Technical field

The present invention relates to trsanscondutance amplifier structure, particularly relate to a kind of trsanscondutance amplifier structure being applicable to the current multiplexing high linearity of down-conversion mixer radio-frequency voltage-current conversion in transceiver receiver.

Background technology

Rf signal reception link, when processing the signal received, needs the interference signal maintained the sufficiently high linearity to suppress because intermodulation produces, because the intermodulation of signal may cause the deterioration of signal to noise ratio.Meanwhile, the blocking effect occurred when the higher linearity also contributes to preventing signal strength signal intensity larger and gain compression effect, thus the power upper limit improving receiver Received signal strength, increase dynamic range.In the receiver of transceiver, the effect of down-conversion mixer is that radiofrequency signal is down-converted to intermediate frequency or baseband signal, and be the maximum one-level of radio-frequency (RF) signal strength, therefore its linearity is enough high, could improve the received power upper limit of whole receiver.

The active down-conversion mixer of current main flow adopts the tertiary structure of transconductance stage, switching stage and load stage substantially, radio frequency voltage signal is converted to current radio frequency signal by transconductance stage, switching stage realizes the frequency conversion effect of current field under the driving of local oscillation signal, and the intermediate frequency after frequency conversion or baseband current signal produce voltage output signal in load stage.The transistor of switching stage switches between dark linear zone and cut-off region, has the very high linearity.The current-voltage conversion of load stage, may use the structures such as trans-impedance amplifier, but in essence often by allowing current signal realize through passive component generation voltage signals such as resistance, therefore also has the very high linearity.The principle of transconductance stage utilizes the small signal-current conversion function working in the mos field effect transistor (MOSFET) of saturation region, radio frequency voltage signal is converted to current radio frequency signal, its linearity and the MOSFET small-signal transconductance linearity have direct relation, therefore often become the bottleneck place of the down-conversion mixer linearity.In sum, the linearity improvement of active down-conversion mixer realizes mainly through optimizing transconductance stage.

Tradition five pipe differential pair structure for amplifying, when input voltage amplitude is less, can keep the good linearity, and when input voltage amplitude is slightly large, the relation curve between differential output current and input voltage can obvious departs from linear relations.In order to increase the linear dynamic range of input signal, asymmetric differential pair group can be adopted, using the superposition of the current-voltage relation curve of two asymmetric differential pairs to obtain overall relation curve.Because the current-voltage relation curve of two differential pairs offsets certain voltage about input voltage to positive and negative both direction respectively, the transfer characteristic that therefore its superposition obtains can keep the good linearity in wider scope.

Calculate formula from the noise factor of cascade system, the available power gain of prime module is larger, and the contribution of noise factor to the overall noise factor of system of post-module is less.Therefore, in order to suppress the impact of post-module noise, should the appropriate available power gain increasing prime module.For down-conversion mixer, under prime module fixes the prerequisite fixing with output impedance, the approach increasing available power gain is exactly improve the transconductance value of transconductance stage.Meanwhile, in order to optimize the noise factor of down-conversion mixer itself, also require that transconductance stage has enough large transconductance value.But, for fixing circuit structure, improve the available power gain of transconductance stage, just need improve bias current or increase transistor breadth length ratio.The former will cause power consumption to improve, and the latter will cause nonlinear increase.

Summary of the invention

Goal of the invention: for solving the problems of the technologies described above, the present invention proposes a kind of trsanscondutance amplifier structure of current multiplexing high linearity, have the advantages that the linearity is high and DC bias current utilance is high, be suitable as the radio frequency transconductance stage of down-conversion mixer in transceiver receiver.

Technical scheme: the technical scheme that the present invention proposes is: a kind of trsanscondutance amplifier structure of current multiplexing high linearity, as the radio frequency transconductance stage of the down-conversion mixer in wireless receiving link, just be provided with, negative input end VIN+, VIN-, just, negative output terminal VOUT+, VOUT-and tail current pipe bias voltage input VB, the trsanscondutance amplifier structure of described current multiplexing high linearity is just being passed through, negative input end VIN+, VIN-received RF voltage signal, radio frequency voltage signal be converted to current radio frequency signal and just pass through, negative output terminal VOUT+, VOUT-exports, described trsanscondutance amplifier structure comprises the asymmetric differential pair group common source amplifying stage identical with a pair structure, asymmetric differential pair group and common source amplifying stage adopt stacked structure to be connected,

Described asymmetric differential pair group comprises P-type mos field effect transistor M P1, MP2, N-type mos field effect transistor MN1, MN2, MN3, MN4, electric capacity C1, C2, C7, C8 and resistance R1, R2, wherein NM1's and NM2 is measure-alike, NM3's and NM4 is measure-alike; The source electrode of MP1, MP2 is connected, and its tie point is connected to power supply; The negative terminal of the grid of MP1, the top crown of C1, R1, the grid of MN1, the grid of MN4 are connected; The negative terminal of the grid of MP2, the top crown of C2, R2, the grid of MN2, the grid of MN3 are connected; The anode of the drain electrode of MP1, the drain electrode of MN1, R1, the drain electrode of MN4, the top crown of C7 are connected, and its tie point is as the negative output terminal VOUT-of the trsanscondutance amplifier structure of current multiplexing high linearity; The drain electrode of the drain electrode of MP2, the drain electrode of MN2, MN3, the anode of R2, the top crown of C8 are connected, and its tie point is as the positive output end VOUT+ of the trsanscondutance amplifier structure of current multiplexing high linearity; The source electrode of NM1 is connected with the source electrode of MN3; The source electrode of MN4 is connected with the source electrode of MN2; MP1, MP2, MN1, MN2, MN3, MN4 provide small signal gain for described asymmetric differential pair group;

Described common source amplifying stage comprises N-type mos field effect transistor MN5, MN6, electric capacity C3, C4, resistance R3, R4 and, electric capacity C6 with inductance L 2 in parallel two resonant circuits forming in parallel with inductance L 1 by electric capacity C5; The negative terminal of the grid of MN5, the upper step of C3, R3 is connected; The bottom crown of C3 is connected with the bottom crown of C1, and its tie point is as the positive input terminal VIN+ of the trsanscondutance amplifier structure of described current multiplexing high linearity; The drain electrode of MN5 is connected with the bottom crown of the bottom crown of C7, C5 and the negative terminal of L1, and the anode of L1 is connected with the top crown of C5, and its tie point is connected with the source electrode tie point of MN1, MN3; The source electrode of MN5 is connected with the source electrode of MN6 and ground connection; The negative terminal of the grid of MN6, the upper step of C4, R4 is connected; The bottom crown of C4 is connected with the bottom crown of C2, and its tie point is as the negative input end VIN-of the trsanscondutance amplifier structure of described current multiplexing high linearity; The drain electrode of MN6 is connected with the bottom crown of the bottom crown of C8, C6 and the negative terminal of L2, and the anode of L2 is connected with the top crown of C6, and its tie point is connected with the source electrode tie point of MN2, MN4; MN5 and MN6 provides small signal gain for described common source amplifying stage, simultaneously as the tail current offset of described asymmetric differential pair group, for asymmetric differential pair group provides DC bias current, realizes the multiplexing of bias current; The anode of R3 and R4 receives the bias voltage of external circuits input as the tail current pipe bias voltage input VB of the trsanscondutance amplifier structure of described current multiplexing high linearity, VB and controls the DC bias current size of whole trsanscondutance amplifier structure;

Radio frequency voltage signal is coupled to the grid of asymmetric differential pair group transistor MP1, MP2, MN1, MN2, MN3, MN4 by electric capacity C1, C2, through the transformation of transistor, forms the first output current at output VOUT+, VOUT-; Radio frequency voltage signal is coupled to the grid of common-source stage transistor MN5, MN6 by electric capacity C3, C4, through the transformation of transistor, is coupled to output VOUT+, VOUT-forms the second output current by electric capacity C7 and C8; The output radio-frequency current of the trsanscondutance amplifier structure of described current multiplexing high linearity is the current signal after the first output current superposes with the second output current.

Preferably, MP1, MP2, MN5, MN6 all have less breadth length ratio relative to MN1, MN2, MN3, MN4.

Beneficial effect: compared with prior art, the present invention has the following advantages:

1, present invention uses asymmetric differential pair group, the linearity of whole trsanscondutance amplifier structure is improved;

2, present invention uses common source amplifying stage supplementing as gain, because common source amplifying stage and asymmetric differential pair group constitute the structure of current multiplexing, therefore while raising gain, do not improve quiescent dissipation, improve bias current utilance.

Accompanying drawing explanation

Fig. 1 is the trsanscondutance amplifier structural representation of the current multiplexing high linearity that the present invention proposes;

Fig. 2 is that existing symmetric difference is to structural representation;

Fig. 3 is the simulation result comparison diagram that the present invention and traditional structure input third order intermodulation point (IIP3);

Fig. 4 is the present invention and the voltage gain simulation result comparison diagram of traditional structure under 200 Ω load resistances.

Embodiment

Below in conjunction with accompanying drawing, the present invention is further described.

Be illustrated in figure 1 the trsanscondutance amplifier structural representation of the current multiplexing high linearity that the present invention proposes, its structure is mainly divided into two parts, i.e. asymmetric differential pair group and common source amplifying stage part.

Described asymmetric differential pair group comprises P-type mos field effect transistor M P1, MP2, N-type mos field effect transistor MN1, MN2, MN3, MN4, electric capacity C1, C2, C7, C8 and resistance R1, R2, wherein NM1's and NM2 is measure-alike, NM3's and NM4 is measure-alike, the size of MP1, MP2 is less than the size of MN1, MN2, MN3, MN4, thus makes the overdrive voltage of MP1, MP2 enough high, can be operated in the bias point that the linearity is higher; The source electrode of MP1, MP2 is connected, and its tie point is connected to power supply; The negative terminal of the grid of MP1, the top crown of C1, R1, the grid of MN1, the grid of MN4 are connected; The negative terminal of the grid of MP2, the top crown of C2, R2, the grid of MN2, the grid of MN3 are connected; The anode of the drain electrode of MP1, the drain electrode of MN1, R1, the drain electrode of MN4, the top crown of C7 are connected, and its tie point is as the negative output terminal VOUT-of the trsanscondutance amplifier structure of current multiplexing high linearity; The drain electrode of the drain electrode of MP2, the drain electrode of MN2, MN3, the anode of R2, the top crown of C8 are connected, and its tie point is as the positive output end VOUT+ of the trsanscondutance amplifier structure of current multiplexing high linearity; The source electrode of NM1 is connected with the source electrode of MN3; The source electrode of MN4 is connected with the source electrode of MN2; MP1, MP2, MN1, MN2, MN3, MN4 provide small signal gain for described asymmetric differential pair group;

Described common source amplifying stage comprises N-type mos field effect transistor MN5, MN6, electric capacity C3, C4, resistance R3, R4 and, electric capacity C6 with inductance L 2 in parallel two resonant circuits forming in parallel with inductance L 1 by electric capacity C5; The negative terminal of the grid of MN5, the upper step of C3, R3 is connected; The bottom crown of C3 is connected with the bottom crown of C1, and its tie point is as the positive input terminal VIN+ of the trsanscondutance amplifier structure of described current multiplexing high linearity; The drain electrode of MN5 is connected with the bottom crown of the bottom crown of C7, C5 and the negative terminal of L1, and the anode of L1 is connected with the top crown of C5, and its tie point is connected with the source electrode tie point of MN1, MN3; The source electrode of MN5 is connected with the source electrode of MN6 and ground connection; The negative terminal of the grid of MN6, the upper step of C4, R4 is connected; The bottom crown of C4 is connected with the bottom crown of C2, and its tie point is as the negative input end VIN-of the trsanscondutance amplifier structure of described current multiplexing high linearity; The drain electrode of MN6 is connected with the bottom crown of the bottom crown of C8, C6 and the negative terminal of L2, and the anode of L2 is connected with the top crown of C6, and its tie point is connected with the source electrode tie point of MN2, MN4; MN5 and MN6 provides small signal gain for described common source amplifying stage, simultaneously as the tail current offset of described asymmetric differential pair group, for asymmetric differential pair group provides DC bias current, realizes the multiplexing of bias current; The anode of R3 and R4 receives the bias voltage of external circuits input as the tail current pipe bias voltage input VB of the trsanscondutance amplifier structure of described current multiplexing high linearity, VB and controls the DC bias current size of whole trsanscondutance amplifier structure;

Radio frequency voltage signal is coupled to the grid of asymmetric differential pair group transistor MP1, MP2, MN1, MN2, MN3, MN4 by electric capacity C1, C2, through the transformation of transistor, forms the first output current at output VOUT+, VOUT-; Radio frequency voltage signal is coupled to the grid of common-source stage transistor MN5, MN6 by electric capacity C3, C4, through the transformation of transistor, is coupled to output VOUT+, VOUT-forms the second output current by electric capacity C7 and C8; The output radio-frequency current of the trsanscondutance amplifier structure of described current multiplexing high linearity is the current signal after the first output current superposes with the second output current.

Below by comparing symmetric difference, the small-signal difference transconductance value of structure and small-signal difference transconductance value of the present invention are illustrated that the present invention can produce useful technique effect.

The expression formula of symmetric difference shown in Fig. 2 to the small-signal difference transconductance value of structure is:

$G_m=\frac{\∂{\mathrm{\ΔI}}_D}{\∂{\mathrm{\ΔV}}_{in}}=\frac{1}{2}{\mathrm{\μC}}_{OX}\frac{W}{L}\frac{\frac{4I_{SS}}{{\mathrm{\μC}}_{OX}W/L}-2{\mathrm{\ΔV}}_{in}^2}{\sqrt{\frac{4I_{SS}}{{\mathrm{\μC}}_{OX}W/L}-{\mathrm{\ΔV}}_{in}^2}}$

Wherein, Δ _iDfor differential output current signal magnitude, Δ V _infor the size of differential input voltage signal, I _sSfor the size of differential-pair tail current, C _oXfor the grid oxic horizon unit-area capacitance of M1, M2, the breadth length ratio that (W/L) is M1, M2, μ is the carrier mobility of M1, M2.Above formula shows, the size of symmetric difference to the small-signal difference transconductance value of structure is relevant with input voltage signal size, and when input voltage size exceedes certain limit, obvious distortion will occur differential pair amplifying circuit.

With symmetric difference to compared with structure, the differential input and output relation curve of asymmetric differential pair there occurs skew about differential output voltage, and input signal corresponding when namely its differential output signal is zero is also non-vanishing.Utilize above-mentioned characteristic, use the asymmetric differential pair that a pair relation curve offset direction is contrary, utilize mode in parallel, output current signal is superposed, just can obtain the small-signal transconductance characteristic of range of linearity broadening.Namely, under the prerequisite that total bias current is identical, when there is the distortion of same degree, this input voltage signal Amplitude Ratio symmetric difference required for asymmetric differential pair group is greater to required input voltage signal amplitude.Above-mentioned situation describes when reasonable in design, and asymmetric differential pair group can increase input linear scope effectively.

In the present invention, asymmetric differential pair group uses resistance R1, R2 to carry out DC self-bias and puts, and AC signal is then coupled to the grid of transistor MP1, MP2 and MN1, MN2, MN3, MN4 by C1, C2; MP1, MP2 and MN1, MN2, MN3, MN4 all provide small-signal transconductance; The size of MP1, MP2 is relatively little, and therefore its overdrive voltage is higher, can be operated in the bias point that the linearity is higher.

MP1, MP2, MN5, MN6 all have less breadth length ratio, make it under the bias current of normal work, all have higher overdrive voltage, the linearity of small-signal transconductance is higher, and the breadth length ratio of MN1, MN2, MN3, MN4 is larger, there is lower overdrive voltage, promote the overall linearity by asymmetric differential pair group.MP1, MP2 can be issued to the overdrive voltage higher than MN1 ~ MN4 in comparable size and equal electric current due to the reason of hole mobility, in order to improve current utilization rate, under the prerequisite not affecting the linearity, the size of MP1, MP2 can be increased to improve current utilization rate as far as possible.

Common source amplifying stage is by mos field effect transistor MN5, MN6 and electric capacity C5 is in parallel with inductance L 1, the electric capacity C6 LC antiresonant circuit that form in parallel with inductance L 2 is formed, mos field effect transistor MN5, MN6 use large resistance R3, R4 to carry out direct current biasing, use electric capacity C7, C8 to carry out AC coupled.Mos field effect transistor MN5, MN6 of two common source amplifying stages, serve as the tail current offset of asymmetric differential pair group respectively, for asymmetric differential pair group provides DC bias current, realize the multiplexing of bias current, there is again the ability that signal amplifies simultaneously, for common source amplifying stage provides small signal gain.Interchange isolation is carried out owing to adopting LC antiresonant circuit, therefore direct voltage nargin is not consumed, whole trsanscondutance amplifier is identical with common five pipe differential pairs to the demand of supply voltage, namely under the prerequisite that total bias current is identical, when there is the distortion of same degree, this input voltage signal Amplitude Ratio symmetric difference required for asymmetric differential pair group wants large to required input voltage signal amplitude.

Noise factor according to cascade system calculates formula, and the available power gain of prime module is larger, stronger to the noise inhibiting ability of post-module.And the calculating formula of the available power gain of n-th grade of module is:

$G_{A,n}={\left(\right|\frac{Z_{in,n}}{Z_{out,n-1}+Z_{in,n}}|\·A_{v,n})}^2\·\frac{R_{out,n-1}}{R_{out,n}}$

Wherein, Z _{in, n}be the input impedance of n-th grade, Z _{out, n-1}be the output impedance of (n-1) level, A _{v, n}be the floating voltage gain of n-th grade, R _{out, n}and R _{out, n-1}be respectively the output resistance of n-th grade and (n-1) level.Formula is visible thus, and the approach increasing available power gain mainly increases floating voltage gain, reduces output resistance.For whole frequency mixer, so-called voltage gain can use changing voltage gain to substitute, and changing voltage gain expressions is

A _v，mixer＝g _TC·α·R _out，mixer

Wherein, g _tCfor total mutual conductance of transconductance stage, α is the conversion coefficient of switching stage frequency conversion effect, R _{out, mixer}for the resistance sizes of load stage.By A _{v, mixer}expression formula substitutes into G _{a, n}expression formula, can obtain

$G_{A,mixer}={\left(\right|\frac{Z_{in,mixer}}{Z_{out,LNA}+Z_{in,mixer}}\left|\right)}^2\·{(g_{TC}\·\mathrm{\α})}^2\·R_{out,mixer}\·R_{out,LNA}$

Wherein, Z _{out, LNA}for the LNA output impedance of prime, Z _{in, mixer}for the input impedance of transconductance stage, R _{out, LNA}for the output resistance size of prime LNA.From above formula, the method improving the available power gain of frequency mixer has increase input impedance, increases output resistance, increases transconductance stage transconductance value etc.Because input impedance is difficult to random raising, so main approach is just only surplus increase output resistance, increase transconductance stage transconductance value.Because frequency mixer often has the index request of changing voltage gain, i.e. A _{v, mixer}for definite value, because α is also fixed value, so g _tCr _{out, mixer}for fixed value.At G _{a, mixer}expression formula in, g _tCfor quadratic term, and R _{out, mixer}for once item, therefore best raising available power gain G _{a, mixer}method be exactly improve the transconductance value g of transconductance stage _tC.

Usually, the method improving transconductance stage transconductance value mainly increases transistor size and increases DC bias current.The problem increasing transistor size is the enhancing that excessive transistor size can cause transistor small signal transconductance nonlinearities, and the linear input range of differential pair also can compress.The problem increasing DC bias current is that power consumption can improve greatly, because ideally, the small-signal transconductance of the mos field effect transistor of saturation region and the evolution of DC bias current are similar to linear, therefore improve the method inefficiency of mutual conductance by increasing electric current.The trsanscondutance amplifier that the present invention proposes adopts stacked structure, and all crystals Guan Jun plays amplification, improves the utilance of electric current.Meanwhile, the breadth length ratio of each transistor is also not very big, therefore its input linear wider range.

Fig. 3 be transistor size corresponding when, emulate the trsanscondutance amplifier structure of current multiplexing high linearity that the present invention of obtaining proposes and the input third order intermodulation point (IIP3) of the traditional five pipe differential pair structure change curve with DC bias current.As can be seen from the results, when electric current is not too large, the IIP3 of the structure that the present invention proposes is much larger than the IIP3 of traditional structure.

Fig. 4 be transistor size corresponding when, emulate the trsanscondutance amplifier structure of current multiplexing high linearity and the change curve of the voltage gain of traditional five pipe differential pair structure with DC bias current that the present invention of obtaining proposes, in artificial circuit, load uses 200 Ω resistance replacements.As can be seen from the results, under identical bias current, the present invention proposes the voltage gain of structure about than traditional five pipe differential pair height 3dB.It can thus be appreciated that when realizing identical voltage gain, this structure is used to save power consumption.Such as realize the voltage gain of-6dB, traditional structure needs the DC bias current consumed to be about 800uA, and the DC bias current only about 350uA needed for this structure, not only save power consumption over half, and IIP3 is higher.

In sum, the trsanscondutance amplifier structure of the current multiplexing high linearity that the present invention proposes has the characteristic of high linearity and high bias currents utilance, compares traditional structure and has obvious improved action.

The above is only the preferred embodiment of the present invention; be noted that for those skilled in the art; under the premise without departing from the principles of the invention, can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (2)

1. the trsanscondutance amplifier structure of a current multiplexing high linearity, as the radio frequency transconductance stage of the down-conversion mixer in wireless receiving link, just be provided with, negative input end VIN+, VIN-, just, negative output terminal VOUT+, VOUT-and tail current pipe bias voltage input VB, the trsanscondutance amplifier structure of described current multiplexing high linearity is just being passed through, negative input end VIN+, VIN-received RF voltage signal, radio frequency voltage signal be converted to current radio frequency signal and just pass through, negative output terminal VOUT+, VOUT-exports, it is characterized in that: comprise the common source amplifying stage that an asymmetric differential pair group is identical with a pair structure, asymmetric differential pair group and common source amplifying stage adopt stacked structure to be connected,

Described asymmetric differential pair group comprises P-type mos field effect transistor M P1, MP2, N-type mos field effect transistor MN1, MN2, MN3, MN4, electric capacity C1, C2, C7, C8 and resistance R1, R2, wherein NM1's and NM2 is measure-alike, NM3's and NM4 is measure-alike; The source electrode of MP1, MP2 is connected, and its tie point is connected to power supply; The negative terminal of the grid of MP1, the top crown of C1, R1, the grid of MN1, the grid of MN4 are connected; The negative terminal of the grid of MP2, the top crown of C2, R2, the grid of MN2, the grid of MN3 are connected; The anode of the drain electrode of MP1, the drain electrode of MN1, R1, the drain electrode of MN4, the top crown of C7 are connected, and its tie point is as the negative output terminal VOUT-of the trsanscondutance amplifier structure of current multiplexing high linearity; The drain electrode of the drain electrode of MP2, the drain electrode of MN2, MN3, the anode of R2, the top crown of C8 are connected, and its tie point is as the positive output end VOUT+ of the trsanscondutance amplifier structure of current multiplexing high linearity; The source electrode of NM1 is connected with the source electrode of MN3; The source electrode of MN4 is connected with the source electrode of MN2; MP1, MP2, MN1, MN2, MN3, MN4 provide small signal gain for described asymmetric differential pair group;

Described common source amplifying stage comprises N-type mos field effect transistor MN5, MN6, electric capacity C3, C4, resistance R3, R4 and, electric capacity C6 with inductance L 2 in parallel two resonant circuits forming in parallel with inductance L 1 by electric capacity C5; The negative terminal of the grid of MN5, the upper step of C3, R3 is connected; The bottom crown of C3 is connected with the bottom crown of C1, and its tie point is as the positive input terminal VIN+ of the trsanscondutance amplifier structure of described current multiplexing high linearity; The drain electrode of MN5 is connected with the bottom crown of the bottom crown of C7, C5 and the negative terminal of L1, and the anode of L1 is connected with the top crown of C5, and its tie point is connected with the source electrode tie point of MN1, MN3; The source electrode of MN5 is connected with the source electrode of MN6 and ground connection; The negative terminal of the grid of MN6, the upper step of C4, R4 is connected; The bottom crown of C4 is connected with the bottom crown of C2, and its tie point is as the negative input end VIN-of the trsanscondutance amplifier structure of described current multiplexing high linearity; The drain electrode of MN6 is connected with the bottom crown of the bottom crown of C8, C6 and the negative terminal of L2, and the anode of L2 is connected with the top crown of C6, and its tie point is connected with the source electrode tie point of MN2, MN4; MN5 and MN6 provides small signal gain for described common source amplifying stage, simultaneously as the tail current offset of described asymmetric differential pair group, for asymmetric differential pair group provides DC bias current, realizes the multiplexing of bias current; The anode of R3 and R4 receives the bias voltage of external circuits input as the tail current pipe bias voltage input VB of the trsanscondutance amplifier structure of described current multiplexing high linearity, VB and controls the DC bias current size of whole trsanscondutance amplifier structure;

Radio frequency voltage signal is coupled to the grid of asymmetric differential pair group transistor MP1, MP2, MN1, MN2, MN3, MN4 by electric capacity C1, C2, through the transformation of transistor, forms the first output current at output VOUT+, VOUT-; Radio frequency voltage signal is coupled to the grid of common-source stage transistor MN5, MN6 by electric capacity C3, C4, through the transformation of transistor, is coupled to output VOUT+, VOUT-forms the second output current by electric capacity C7 and C8; The output radio-frequency current of the trsanscondutance amplifier structure of described current multiplexing high linearity is the current signal after the first output current superposes with the second output current.

2. the trsanscondutance amplifier structure of a kind of current multiplexing high linearity according to claim 1 and 2, it is characterized in that, MP1, MP2, MN5, MN6 all have less breadth length ratio relative to MN1, MN2, MN3, MN4.