CN101188402B - A low-voltage frequency mixer - Google Patents

Abstract

The invention provides a low-voltage CMOS folding co-source co-grid mixer. The mixer includes the following parts: a pair of transconductance poles composed of NMOS tubes, tow pairs of switch poles composed of NMOS tubes, a pair of load poles composed of NMOS, and a current source. In the structure of the mixer circuit, the transconductance poles are connected with the switch poles in a co-sourceco-grid method. The invention solves the problems of the high power supply high voltage caused by the overlapping of the transconductance poles and the switch poles of the traditional Gilbert mixer, and the compromise design between the high transconductance and the high linearity of the transconductance poles and the low noise of the switch poles. The invention can be used in the application of the deep submicron RF CMOS circuit, in particular in the design developing of the satellite navigation double-system compatible receiver radio frequency integrated circuit. The invention has bright application prospect in both the military and the civilian fields.

Description

A kind of low-voltage frequency mixer

Technical field

The invention belongs to deep-submicron RF CMOS integrated circuit fields, be specifically related to a kind of low voltage CMOS folded common source and common grid frequency mixer.

Background technology

Frequency mixer is the important component part in the navigation neceiver, is mainly used to realize the conversion of frequency.Some performance parameter of frequency mixer directly affects the performance of whole navigation neceiver, for example: the conversion gain of frequency mixer is determining the influence degree of the back level module of frequency mixer in the navigation neceiver to systematic function, the reduction of frequency mixer power consumption has material impact to the reduction of receiver system power dissipation, the raising of mixer linearity degree plays key effect to the improvement of the whole receiver linearity, and the noise of frequency mixer is also having a strong impact on the sensitivity of receiver.Therefore, for the navigation neceiver system, the frequency mixer that has function admirable is very important.

Fast development along with portable type electronic product and deep submicron integrated circuit technology, standard complementary metal oxide semiconductors (CMOS) (Complementary Metal-Oxide-Semiconductor, abbreviation CMOS) supply voltage that technology allowed is more and more lower, and low pressure and low consumption has become the important development direction of integrated circuit (IC) design industry; And reduce the power consumption of system by the supply voltage that reduces system, be a kind of the most effective way.Along with constantly reducing of transistor feature size and grid oxide layer thickness, only need lower voltage just can guarantee the operate as normal of electronic device, 1.8V (0.18 μ m) supply voltage now is widely used, the supply voltage of 1.2V (0.13 μ m) and 0.9V (90nm) also is applied to the design and the production of electronic device and SOC (system on a chip) successively.In addition, the portable electric appts in the fields such as military and Aero-Space also needs the low pressure and low consumption circuit to prolong the useful life of battery, can normally stably work in a long time with the assurance system.

Current main frequency mixer all adopts Gilbert type frequency mixer.The structure of standard Gilbert type frequency mixer is as shown in Figure 1: NMOS pipe 1 provides bias current I for entire circuit _SSNMOS pipe 2 and NMOS pipe 3 are formed the common source pipes, have constituted transconductance stage, convert the radio-frequency differential voltage signal RF of input to current signal and it is amplified; Local oscillator differential voltage signal LO is input to four grids by NMOS pipe 4 to NMOS pipes 7 switching stages of forming respectively.By local oscillator differential voltage signal LO the modulation of the drain electrode output current of NMOS pipe 2 and NMOS pipe 3 is realized mixing, and current signal is converted into middle frequency difference divided voltage signal IF output by medium frequency load resistor 8 and resistance 9.As can be seen from Figure 1, there is following several problem in standard Gilbert type frequency mixer aspect the improving of low pressure and low consumption design, conversion gain, the linearity and noiseproof feature:

The first, be unfavorable for the low pressure and low consumption design.Transconductance stage NMOS pipe 2,3 and switching stage NMOS pipe 4～7 are stacked between power supply and the ground, have reduced the voltage remaining, and system need provide bigger supply voltage could guarantee certain range of linearity.Therefore, standard Gilbert type frequency mixer has seriously limited the reduction of supply voltage, is unfavorable for the realization of low power dissipation design.

The second, strengthened the difficulty of the design of trading off between the linearity and noiseproof feature, the linearity and the conversion gain.If switching stage is approximately perfect switch, then the linearity of whole frequency mixer is mainly determined by transconductance stage; And the non-linear phenomena of CMOS frequency mixer causes by the square-law characteristic of transconductance stage metal-oxide-semiconductor, so, can improve the linearity of frequency mixer in the restriction aspect non-linear by improving transconductance stage.Following several common methods is arranged usually: can adopt the frequency mixing technique of owing to sample to improve the linearity, but can cause noise factor to increase, reduce noiseproof feature, the design of promptly need between the linearity and noiseproof feature, trading off; Can add negative feedback at the source electrode of standard Gilbert type frequency mixer transconductance stage, but can cause the decline of conversion gain, the design of promptly need between the linearity and conversion gain, trading off; Can make transconductance stage be operated in linear condition, but can cause the decline of conversion gain equally, the design of also need between the linearity and conversion gain, trading off.

In addition, weigh the typical index of mixer linearity degree---import three rank point of cut-off IIP3 and transconductance stage bias current I _SSRelation in direct ratio increases, therefore, and also can be by improving transconductance stage bias current I _SSImprove the linearity.Transconductance stage NMOS pipe 2,3 and switching stage NMOS manage 4～7 series stack between power supply and ground in the standard Gilbert type frequency mixer, transconductance stage bias current I but as shown in Figure 1, _SSThe raising nature can cause and the raising of switching stage NMOS pipe 4～7 bias currents cause the deterioration (seeing the hereinafter argumentation of the 4th problem for details) of switching stage NMOS pipe 4～7 noiseproof features, the design of promptly need between the linearity and noiseproof feature, trading off.

The 3rd, strengthened the difficulty of compromise design between conversion gain and the noiseproof feature.As shown in Figure 1, if being managed 4～7, switching stage NMOS is approximately perfect switch, then the conversion gain G of whole frequency mixer _CMainly, promptly depend primarily on the mutual conductance g of transconductance stage by the transconductance stage decision _M2,3, be shown below:

${\mathrm{<figure-callout\; id="2"\; label="g\; m"\; filenames="H2007101799793E00011.png"\; state="\{\{state\}\}">\; <figure-callout\; id="3"\; label="g\; m"\; filenames="H2007101799793E00011.png"\; state="\{\{state\}\}">g</figure-callout>\; </figure-callout>}}_m=2\sqrt{\frac{1}{2}{\mathrm{\&mu;}}_n{C}_{\mathrm{OX}}\frac{W}{L}(1+{\mathrm{\&lambda;V}}_{\mathrm{DS}}){\mathrm{<figure-callout\; id="2"\; label="I\; D"\; filenames="H2007101799793E00011.png"\; state="\{\{state\}\}">I</figure-callout>}}_D}---\left(1\right)$

In the formula (1), electron mobility μ _n=600～800cm ²/ (Vgs), C _OXBe constant with λ, as source-drain voltage V _DS, when technological parameter breadth length ratio W/L is definite value, can be by increasing the operating current I of transconductance stage NMOS pipe 2,3 _D2,3Increase g _M2,3In conjunction with Fig. 1 as can be known:

$I_{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="H2007101799793E00011.png"\; state="\{\{state\}\}">\; <figure-callout\; id="3"\; label="D"\; filenames="H2007101799793E00011.png"\; state="\{\{state\}\}">D</figure-callout>\; </figure-callout>}\mathrm{2,3}}=\frac{1}{2}{I}_{\mathrm{SS}}---\left(2\right)$

Can be by increasing I _SSImprove mutual conductance g _M2,3But by aforementioned second problem as can be known, can cause the deterioration of switching stage NMOS pipe 4～7 noiseproof features like this, the design of promptly need between conversion gain and noiseproof feature, trading off.

The 4th, be unfavorable for the improvement of noiseproof feature.There is the thermal noise and the flicker noise of the thermal noise of resistance, metal-oxide-semiconductor in the main noise source that influences CMOS mixer noiser performance.In the lower CMOS down-conversion mixer of frequency, flicker noise is main low-frequency noise: for resistance, only when flowing through direct current in the resistance, flicker noise is arranged; For metal-oxide-semiconductor, can increase wide (width is called for short W) and long (length is called for short L) of its grid, promptly by increasing grid source parasitic capacitance C _GsReduce the corner frequency of flicker noise, and then reduce flicker noise.The flicker noise of frequency mixer input stage is because the effect of frequency inverted only appears at output near the odd harmonic of local frequency, and away from intermediate-freuqncy signal, this influence can be ignored usually; When there was offset voltage in switching tube, the flicker noise of input stage will exert an influence to the intermediate-freuqncy signal of output, but because numerical value is very little, also can be left in the basket; And when the intermediate frequency output signal frequency of frequency mixer was higher, the thermal noise that reduces resistance and metal-oxide-semiconductor should be a key of improving the mixer noiser performance.

Resistance Thermal Noise can reduce by reduction temperature, reduction system bandwidth.For the metal-oxide-semiconductor of transconductance stage, can reduce the thermal noise that it produces at output by the grid source effective voltage that increases the switching stage metal-oxide-semiconductor, the amplitude that reduces local oscillation signal.Under the situation of not considering parasitic capacitance, the power spectral density of the thermal noise electric current of switching stage output only is directly proportional with bias current, is inversely proportional to the amplitude of local oscillation signal.Therefore, be under the situation of definite value in the grid source effective voltage and the local oscillation signal amplitude of switching stage metal-oxide-semiconductor, the bias current that reduces switching stage can reduce thermal noise; Otherwise as described in second and third problem of preamble, increase switching stage biased electrical fails to be convened for lack of a quorum and causes the deterioration of mixer noiser performance.

Summary of the invention

The objective of the invention is based on a kind of folded common source and common grid structure, a kind of low voltage CMOS folded common source and common grid frequency mixer (folded-cascode mixer is provided, be called for short FCM), can be used for the application of deep-submicron RF cmos circuit, be particularly useful for the development and design of satellite navigation dual system compatible receiver radio frequency integrated circuit.

A kind of low voltage CMOS folded common source and common grid frequency mixer provided by the invention comprises following a few part: the switching stage of the transconductance stage that a pair of NMOS pipe is formed, two pairs of NMOS pipe compositions, load stage and the current source that a pair of NMOS pipe is formed.Mode with folded common source and common grid between the transconductance stage of this frequency mixer and the switching stage is connected, the source electrode that the substrate of all metal-oxide-semiconductors is all corresponding with it in the circuit connects, solve in the standard Gilbert type frequency mixer transconductance stage and switching stage and piled up the high power supply voltage problem of bringing, and a compromise difficult problem that designs between the low noise of the high transconductance of transconductance stage, high linear and switching stage; The low pressure and low consumption design of frequency mixer, the improvement that the while also helps conversion gain, power consumption, the linearity and the noiseproof feature of frequency mixer have been realized.

The supply voltage of reduction system can reduce the power consumption of system greatly.Adopt foldable structure among the present invention, reduced the requirement of system, help realizing the reduction of power consumption supply voltage.

See into to transconductance stage and switching stage respectively that from two common drains of switching stage the former impedance will be much smaller than the latter's impedance, therefore, the bias current overwhelming majority that current source provides flows to transconductance stage, becomes the bias current of transconductance stage; Have only a part seldom to flow into switching stage, become the bias current of switching stage.Less bias current helps to reduce the thermal noise that switching stage produces, and improves the noiseproof feature of frequency mixer.

Switching stage is being approximately under the situation of perfect switch, can improving the linearity of transconductance stage, and then improving the linearity of frequency mixer, promptly increasing the output current of current source by the bias current that improves transconductance stage; As can be known described by preamble, the bias current that flows through switching stage only accounts for the seldom part that current source provides bias current, therefore the output current that increases current source can't cause the remarkable increase of switching stage bias current, can not cause the obvious deterioration of noiseproof feature, reduce the difficulty of compromise design between the linearity and the noiseproof feature.Improve the linearity and needn't adopt transconductance stage source electrode commonly used to add degenerative mode again this moment, promptly avoided the design of trading off between the linearity and conversion gain.

Owing to when increasing the output current of current source, can't cause the obvious increase of switching stage bias current.Therefore, increase the transconductance stage gain, when improving conversion gain, can not cause the obvious deterioration of switching stage noiseproof feature, alleviated in standard Gilbert type frequency mixer the difficulty of compromise design between the conversion gain and noiseproof feature.

In addition, switching stage and load stage among the FCM of the present invention are connected in series, because the bias current that flows through switching stage seldom, the bias current of the load stage that causes flowing through also seldom, make load stage that higher output impedance can be provided, help increasing the conversion gain of frequency mixer.Among the FCM of the present invention, replaced the load resistance R of standard Gilbert type frequency mixer with load stage NMOS pipe, the output impedance that provides can reach more than the hundreds of M Ω; And, can not cause the pressure drop on the load impedance excessive, can not cause the working point low excessively, improved the voltage remaining of circuit, be beneficial to the realization of low pressure and low consumption design.In order to obtain higher output impedance, load stage can be expanded to the stacked of two groups or more devices, but the increase that can bring extra voltage remaining demand simultaneously is unfavorable for the realization of low-pressure designs.

In addition, because on the device matching that CMOS technology is made, the NMOS pipe is better than resistance R.The impedance magnitude of load stage is directly connected to the size of conversion gain in FCM, therefore, with the load resistance R in the NMOS pipe replacement standard Gilbert type frequency mixer, can improve the precision of frequency mixer.

FCM compares with standard Gilbert type frequency mixer, and following advantage is arranged:

(1) solves in the standard Gilbert type frequency mixer transconductance stage and switching stage and piled up the high power supply voltage problem of bringing, helped the realization of low pressure and low consumption design;

(2) solve the difficult problem of trading off and designing between the low noise of the high transconductance of transconductance stage, high linearity and switching stage, helped the improvement of mixer noiser performance;

(3) reduced the compromise difficulty that designs between the linearity and noiseproof feature, the linearity and the conversion gain;

(4) reduced the compromise difficulty that designs between conversion gain and the noiseproof feature;

(5) replace load resistance R in the standard Gilbert type frequency mixer with a pair of NMOS pipe, when bigger output impedance can be provided, improved the precision of frequency mixer.

Description of drawings

Fig. 1 is standard Gilbert type double balanced mixer figure;

Fig. 2 is the circuit diagram of low voltage CMOS folded common source and common grid frequency mixer of the present invention;

The impedance schematic diagram that Fig. 3 sees into from the A point for the transconductance stage of mixer core circuit of the present invention;

The impedance schematic diagram that Fig. 4 sees into from the A point for the switching stage of mixer core circuit of the present invention.

Embodiment

The present invention is further detailed explanation below in conjunction with accompanying drawing.

Fig. 2 is the circuit diagram of low voltage CMOS folded common source and common grid frequency mixer of the present invention.FCM provided by the invention comprises following a few part: the switching stage of the transconductance stage that a pair of NMOS pipe is formed, two pairs of NMOS pipe compositions, load stage and the current source that a pair of NMOS pipe is formed.Mode with folded common source and common grid between the transconductance stage of this frequency mixer and the switching stage is connected, and load stage has adopted a pair of NMOS pipe, the source electrode connection that the substrate of all metal-oxide-semiconductors is all corresponding with it in the circuit.

The transconductance stage of mixer is connected to form in the common source mode by a pair of NMOS pipe 10,11: a pair of radio-frequency differential voltage signal RF+, RF-are from two grids inputs of this a pair of NMOS pipe 10,11, two source groundings of this a pair of NMOS pipe 10,11, two drain electrodes link to each other with corresponding two common drain A, B in the switching stage respectively.

The switching stage of mixer is made up of two pairs of NMOS pipes 12～15: the drain electrode of first NMOS pipe 12 is connected with the drain electrode of the 3rd NMOS pipe 14, the drain electrode of second NMOS pipe 13 is connected with the drain electrode of four NMOS pipe 15, and two drain electrodes of transconductance stage NMOS pipe 10,11 link to each other with two common drain A, B of these two pairs of NMOS pipes 12～15 respectively; The grid of first NMOS pipe 12 is connected with the grid of four NMOS pipe 15, the grid of second NMOS pipe 13 is connected with the grid of the 3rd NMOS pipe 14, and a pair of local oscillator differential voltage signal LO+, LO-are from two common gate C, D inputs of these two pairs of NMOS pipes 12～15; The source electrode of first NMOS pipe 12 is connected with the source electrode of second NMOS pipe 13, the source electrode of the 3rd NMOS pipe 14 is connected with the source electrode of four NMOS pipe 15, and a pair of middle frequency difference divided voltage signal IF+, IF-are from two common source E, F outputs of these two pairs of NMOS pipes 12～15.

The load stage of mixer is made up of a pair of NMOS pipe 16,17: the grid of a pair of NMOS pipe 16,17 connects, drain electrode is connected with two common source E, F of switching stage respectively, source electrode all is connected with ground GND, and bias voltage Vbr imports this common gate G to NMOS pipe 16,17.

As shown in Figure 2, current source Irf is connected respectively by two grids of a pair of resistance 18,19 with a pair of NMOS pipe 10,11 of transconductance stage, current source Ilo is connected respectively two common gate C, the Ds of resistance 20,21 with two pairs of NMOS pipes 12～15 of switching stage by another, current source Issa is connected between the common drain A of two couples of NMOS pipe 12～15 of power vd D and switching stage, and current source Issb is connected between another common drain B of two pairs of NMOS pipes 12～15 of power vd D and switching stage.

A pair of radio-frequency differential voltage signal RF+, the RF-of FCM shown in Fig. 2 import transconductance stage, a pair of local oscillator differential voltage signal LO+, LO-difference input switch level, and a pair of middle frequency difference divided voltage signal IF+, IF-are from difference output between switching stage and the load stage; Load stage provides load impedance for frequency mixer; Current source provides various bias currents for frequency mixer.Wherein, the output current of current source Issa and Issb provides bias current for transconductance stage and the switching stage of FCM; The electric current that current source Irf provides by a pair of resistance 18,19 for transconductance stage provides gate bias voltage, so that it works in the saturation region; The electric current that current source Ilo provides by another to resistance 20,21 for switching stage provides gate bias voltage, so that it can work on off state under the effect of a pair of local oscillator differential voltage signal LO+, LO-; Bias voltage Vbr provides gate bias voltage for load stage, so that it works in the saturation region, for FCM provides load impedance.

FCM provided by the present invention compares with standard Gilbert type frequency mixer, and following characteristics and improvement are arranged:

The first, the supply voltage that reduces system can reduce the power consumption of system greatly; And the FCM among the present invention adopts foldable structure, adopts the structure of folded common source and common grid to be connected between transconductance stage and the switching stage, has reduced the requirement of system to supply voltage, has realized the low pressure and low consumption design.

Second, transconductance stage NMOS pipe 10,11 produces the small-signal drain current that is directly proportional with the radio frequency input voltage, the small-signal drain currents that switching stage NMOS pipe 12～15 produces transconductance stage NMOS pipe 10, the 11 load stage NMOS pipe 16,17 of flowing through changes into a pair of middle frequency difference divided voltage signal IF+, the output of IF-difference.The output current of current source Issa and Issb provides bias current for transconductance stage NMOS pipe 10,11 and the switching stage NMOS pipe 12～15 of FCM; Since from A point or B point to transconductance stage and switching stage minute although enter, the latter's impedance will be much larger than the former impedance, because this FCM circuit structure symmetry, so only to see into from the A point and to be example with the left half of circuit of switching stage NMOS pipe 12～15, when a pair of local oscillator differential voltage signal LO+, LO-make NMOS manage 12 conductings, NMOS pipe 13 by the time, as shown in Figure 3 and Figure 4.

As seen from Figure 3, see into to transconductance stage NMOS pipe 10 from the A point that the circuit diagram that the circuit diagram in left side can be reduced to the right side among Fig. 3 is analyzed, this moment, this circuit can be considered a resistance r _O10, then its output impedance is:

R ₁₀＝r _o10 (3)

As seen from Figure 4, see into to switching stage NMOS pipe 12 from the A point that the circuit diagram that the circuit diagram in left side can be reduced to the right side among Fig. 4 is analyzed, this moment, left half of circuit can be considered a band negative feedback resistor r _O16Common source, then its output impedance is:

R ₁₂＝[1+(g _m12+g _mb12)r _o12]r _o16+r _O12(4)

In FCM of the present invention, the latter's impedance R ₁₂Can be designed as and be about as much as the former impedance R ₁₀10 ⁵Doubly, therefore, the output current of current source Issa and Issb almost all flows to transconductance stage NMOS pipe 10,11, and for transconductance stage NMOS pipe 10,11 provides bias current, the bias current of transconductance stage is equivalent to the I in the formula (2) at this moment _SSHave only about 1/10 ⁵Current source Issa and the output current of Issb flow to switching stage NMOS pipe 12～15, become the bias current of switching stage NMOS pipe 12～15, promptly help to reduce the thermal noise that switching stage produces, improve the noiseproof feature of frequency mixer.

The 3rd, switching stage NMOS pipe 12～15 is being approximately under the situation of perfect switch, can improve the linearity of transconductance stage by the bias current that improves transconductance stage NMOS pipe 10,11, and then improve the linearity of frequency mixer, promptly increase the output current of current source Issa and Issb; Owing to can't cause the remarkable increase of switching stage NMOS pipe 12～15 bias currents, therefore can not cause the obvious deterioration of noiseproof feature, reduced the difficulty of compromise design between the linearity and the noiseproof feature.Improve the linearity and needn't adopt the transconductance stage source electrode to add degenerative mode again this moment, promptly avoided the design of trading off between the linearity and conversion gain.

The 4th, in FCM of the present invention, the bias current of switching stage NMOS pipe 12～15 approximately only accounts for current source Issa and Issb provides 1/10 of bias current owing to flow through ⁵, when increasing the output current of current source Issa and Issb, can't cause the obvious increase of switching stage NMOS pipe 12～15 operating currents.Therefore, increase the transconductance stage gain, when improving conversion gain, can not cause the obvious deterioration of switching stage noiseproof feature, alleviated in standard Gilbert type frequency mixer the difficulty of compromise design between the conversion gain and noiseproof feature.

The 5th, because the bias current that flows through switching stage NMOS pipe 12～15 seldom, the bias current of the load stage NMOS pipe 16,17 that causes flowing through also seldom makes load stage NMOS pipe 16,17 that high output impedance can be provided, and helps increasing the conversion gain of frequency mixer.Formula (5) as follows:

${\mathrm{<figure-callout\; id="16"\; label="r\; ds"\; filenames="H2007101799793E00021.png,H2007101799793E00032.png"\; state="\{\{state\}\}">\; <figure-callout\; id="17"\; label="r\; ds"\; filenames="H2007101799793E00021.png"\; state="\{\{state\}\}">r</figure-callout>\; </figure-callout>}}_{\mathrm{ds}}\&ap;\frac{1}{\mathrm{\&lambda;}}\&CenterDot;\frac{1}{I_{\mathrm{<figure-callout\; id="16"\; label="D"\; filenames="H2007101799793E00021.png,H2007101799793E00032.png"\; state="\{\{state\}\}">D</figure-callout>}\mathrm{16,17}}}---\left(5\right)$

Load stage NMOS pipe 16,17 all works in the saturation region.In the formula, r _Ds16,17Be the output impedance of load stage NMOS pipe 16 or 17; λ is the raceway groove index of modulation, and representative value is 10 ^-2/ V; I _D16,17Drain current for load stage NMOS pipe 16 or 17.By following formula as seen, r _Ds16,17Drain current I with NMOS pipe 16 or 17 _D16,17Be inversely proportional to, very little drain current I promptly only is provided _D16,17, just can obtain very high load impedance.Among the FCM of the present invention, replaced the load resistance R8,9 of standard Gilbert type frequency mixer with load stage NMOS pipe 16,17, the output impedance that provides can reach more than the hundreds of M Ω; And, can not cause the pressure drop on the load impedance excessive, can not cause the working point low excessively, improved the voltage remaining of circuit, be beneficial to the realization of low pressure and low consumption design.In order to obtain higher output impedance, load stage NMOS pipe 16,17 can be expanded to the stacked of two groups or more devices, but the increase that can bring extra voltage remaining demand simultaneously is unfavorable for the realization of low-pressure designs.

In addition, because on the device matching that CMOS technology is made, the NMOS pipe is better than resistance R.The impedance magnitude of load stage NMOS pipe 16,17 is directly connected to the size of conversion gain in FCM, and therefore, the load resistance R with in the NMOS pipe replacement standard Gilbert type frequency mixer can improve the precision of frequency mixer when big output impedance is provided.

Claims (5)

1. low-voltage frequency mixer, it is characterized in that, this frequency mixer comprises following a few part: the transconductance stage that a pair of NMOS pipe is formed, two pairs of switching stages that the NMOS pipe is formed, load stage and current source that a pair of NMOS pipe is formed, mode with folded common source and common grid between the transconductance stage of this frequency mixer and the switching stage is connected, load stage is connected between the source electrode and ground of switching stage, a pair of current source is connected between the drain electrode and power supply of switching stage, another is connected between the grid and ground of transconductance stage to current source, between the grid and ground of switching stage, the source electrode that the substrate of all metal-oxide-semiconductors is all corresponding with it in the frequency mixer connects.

2. a kind of low-voltage frequency mixer according to claim 1, the transconductance stage that it is characterized in that described frequency mixer is managed (10,11) by a pair of NMOS and is connected to form in the common source mode:

Radio-frequency differential voltage signal (RF+, RF-) is from two grid inputs of this a pair of NMOS pipe (10,11), and this a pair of NMOS manages two source groundings of (10,11), and two drain electrodes link to each other with corresponding two common drains (A, B) in the switching stage respectively.

3. a kind of low-voltage frequency mixer according to claim 1, the switching stage that it is characterized in that described frequency mixer is managed (12～15) by two couples of NMOS and is formed:

The drain electrode of first NMOS pipe (12) is connected with the drain electrode of the 3rd NMOS pipe (14), the drain electrode of second NMOS pipe (13) is connected with the drain electrode of four NMOS pipe (15), and two drain electrodes of transconductance stage NMOS pipe (10,11) link to each other with two common drains (A, B) of these two pairs of NMOS pipes (12～15) respectively;

The grid of first NMOS pipe (12) is connected with the grid of four NMOS pipe (15), the grid of second NMOS pipe (13) is connected with the grid of the 3rd NMOS pipe (14), and local oscillator differential voltage signal (LO+, LO-) is from two common gates (C, D) input of these two pairs of NMOS pipes (12～15);

The source electrode of first NMOS pipe (12) is connected with the source electrode that second NMOS manages (13), the source electrode of the 3rd NMOS pipe (14) is connected with the source electrode of four NMOS pipe (15), and middle frequency difference divided voltage signal (IF+, IF-) is from two common sources (E, F) output of these two pairs of NMOS pipes (12～15).

4. a kind of low-voltage frequency mixer according to claim 1, the load stage that it is characterized in that described frequency mixer is managed (16,17) by a pair of NMOS and is formed:

The grid of a pair of NMOS pipe (16,17) connects, and drain electrode is connected with two common sources (E, F) of switching stage respectively, and source electrode all is connected with ground (GND), and bias voltage Vbr imports this common gate (G) to NMOS pipe (16,17).

5. a kind of low-voltage frequency mixer according to claim 1 is characterized in that:

The current source Irf of described frequency mixer is connected respectively by two grids of a pair of resistance (18,19) with a pair of NMOS pipe (10,11) of transconductance stage;

The current source Ilo of described frequency mixer is connected respectively two common gates (C, D) of resistance (20,21) with two pairs of NMOS pipes (12～15) of switching stage by another;

Two couples of NMOS that the current source Issa of described frequency mixer is connected in power supply (VDD) and switching stage manage between the common drain (A) of (12～15);

Two couples of NMOS that the current source Issb of described frequency mixer is connected in power supply (VDD) and switching stage manage between another common drain (B) of (12～15).

Images