CN101783654B - High-gain broadband radio-frequency low noise amplifier - Google Patents

Abstract

The invention discloses a high-gain broadband radio-frequency low noise amplifier. A radio-frequency signal is input to the grid electrode of a MOS pipe NM2 by an inductor L0, the drain electrode of the NM2 is connected with a power source Vdd by a resistor R7, the source electrode of the NM2 is earthed, both ends of a capacitor C8 are respectively connected with the grid electrode and the drain electrode of the NM2, the drain electrode of the NM2 is connected with the grid electrode of a MOS pipe NM1 by a capacitor C9, the drain electrode of the NM1 is connected with the power source Vdd by an inductor L1 and a resistor R0 which are connected in series, the source electrode of the NM1 is earthed, both ends of a capacitor R1 are respectively connected with the grid electrode and the drain electrode of the NM1, both ends of a resistor R2 are respectively connected with the grid electrode and the source electrode of the NM1, the grid electrode and the drain electrode of a MOS pipe NM0 are in short-circuit connection, both ends of a resistor R8 are respectively connected with the grid electrodes of the NM2 and the NM0, the drain electrode of the NM0 is connected with the power source Vdd by a resistor R5, the source electrode of the NM0 is earthed, and both ends of a capacitor C2 are respectively connected with the grid electrode and the source electrode of the NM0. The invention has certain advantages in the aspects of input match, gain, noise and the like. Besides, the number of the used inductors of the invention is far less than that of the conventional amplifier, and therefore, the area of a chip is obviously reduced.

Description

A kind of high-gain broadband radio-frequency low noise amplifier

Technical field

The present invention relates to amplifier, relate in particular to a kind of high-gain broadband radio-frequency low noise amplifier.

Background technology

In recent years; Flourish along with radio communication and microelectric technique; The user of radio communication is the wireless handset users rapid growth particularly, and this has higher requirement to modern communications, particularly the 3G (Third Generation) Moblie technology; Its core business no longer is confined to voice, image, but the multimedia service of requirements at the higher level.This just requires capability of communication system constantly to enlarge, and the reliability and the fail safe of information improve constantly, and cause communications band more and more crowded.In order to change this situation, people have proposed the utilization ratio that various technology improve frequency spectrum.As (like OFDM, WCDMA) to improve transmission of Information efficient and reliability, digital modulation technique (like QPSK and 64QAM etc.) is to reach channel space distribution widely efficiently to adopt new wideband digital transmission technology.Because these technological message transmission all develop towards the direction of big capacity, multicarrier, many level, broadband and higher peak-to-average force ratio, this has proposed very high requirement to power amplifier.And, reduce cooling cost in order to reduce the operation cost of common carrier, and be easy to thermal control, just require to improve the efficient of power amplifier; Usage quantity for the sum of series power tube that reduces power amplification drives with lower power, reduces cost, and just requires to improve the gain of power amplifier; In order to increase the coverage of communication base station, the base station that reduces required setting in the FX reduces the size and the weight of circuit simultaneously to practice thrift cost, just requires to improve the power output of power amplifier.These all problems, all the design to power amplifier has proposed new requirement.

The wide band radio-frequency communicating requirement can have high data transmission rate and low in power consumption simultaneously, and the key issue of The Wide-Band Design is in a very wide bandwidth range, to keep the input coupling.On the other hand, the broadband operation network is to more responsive with inside and outside unwanted signal, so the linear of broadband reception device becomes more important.Low noise amplifier (LNA) is the unit of often using in the broadband system; Especially in the middle of wireless receiver; Will amplify through LNA from the faint small-signal of antenna feed-in, take the back level again and handle, its performance directly has influence on the overall performance of receiver.Therefore the LNA that designs a big bandwidth is an important link in the wireless system design.Different input matching process has caused the difference of LNA structure, and traditional input matching way has the inductance coupling, directly grid coupling etc. is mated, is total to resistors match, parallel resistance feedback, but they all can't guarantee the input coupling on the frequency range of broadband.The wideband operation frequency also is a challenge for the gain of circuit because in the circuit design because the restriction of gain bandwidth product, bandwidth needs to trade off each other with gain.Simultaneously, the small-signal transmission needs the noise factor NF (noise figure) of system also will reach the requirement of system, and also exists important trading off between input coupling and the noise factor.These all are the difficult points that present broadband LNA design exists

Summary of the invention

The objective of the invention is provides a kind of high-gain broadband radio-frequency low noise amplifier in order to overcome the weak point of prior art.

In the high-gain broadband radio-frequency low noise amplifier, radiofrequency signal is through the grid of inductance L 0 input metal-oxide-semiconductor NM2, and the drain electrode of metal-oxide-semiconductor NM2 is connected with power supply Vdd through resistance R 7; The source ground of metal-oxide-semiconductor NM2, capacitor C 8 two ends are connected with drain electrode with the grid of metal-oxide-semiconductor NM2 respectively, and the output of metal-oxide-semiconductor NM2 is connected with the grid of the second rank amplifier metal-oxide-semiconductor NM1 through capacitor C 9; The drain electrode of metal-oxide-semiconductor NM1 is connected with power supply Vdd with resistance R 0 through the inductance L 1 of series connection; The source ground of metal-oxide-semiconductor NM1, electric capacity R1 two ends are connected with drain electrode with the grid of metal-oxide-semiconductor NM1 respectively, and resistance R 2 two ends are connected with source electrode with the grid of metal-oxide-semiconductor NM1 respectively; The grid of metal-oxide-semiconductor NM0 and drain electrode short circuit; The grid of metal-oxide-semiconductor NM0 is connected back voltage Vbias for referencial use with resistance R 8, be connected with the grid of metal-oxide-semiconductor NM2, and the drain electrode of metal-oxide-semiconductor NM0 is connected with power supply Vdd through resistance R 5; The source ground of metal-oxide-semiconductor NM0, capacitor C 2 two ends are connected with source electrode with the grid of metal-oxide-semiconductor NM0 respectively.

Amplifier index of the present invention is: bandwidth of operation is at 2.3～3.8GHz, and input reflection coefficient S11 has reached the coupling requirement less than-9.34dB; Power gain (S21) is 12.6dB～14.2dB, and fluctuation range has only 1.6dB; Noise factor NF is 2.39dB～2.59dB in the whole frequency band scope, and input 1dB compression point be-4.2dBm, imports three rank section IIP3 to be-24.6dBm, and chip area as shown in Figure 2 is 0.356mm2 (0.99mm * 0.36mm).The present invention has certain advantage at aspects such as input coupling, power gain, noises, and since the inductance number that uses far fewer than traditional amplifier, chip area has obtained reducing significantly.

Description of drawings

Fig. 1 is the high-gain broadband radio-frequency low noise amplifier circuit diagram;

Fig. 2 is the domain of radio frequency low-noise amplifier of the present invention;

Fig. 3 is the small-signal equivalent schematic diagram of amplifier input coupling of the present invention;

Fig. 4 is simplified to the Principle of Process figure of equivalent model for amplifier input coupling of the present invention;

Fig. 5 (a) is the amplifier first rank small-signal equivalent circuit schematic diagram of the present invention;

Fig. 5 (b) is the second rank small-signal equivalent circuit schematic diagram of amplifier.

Embodiment

As shown in Figure 1, in the high-gain broadband radio-frequency low noise amplifier, radiofrequency signal is through the grid of inductance L 0 input metal-oxide-semiconductor NM2; The drain electrode of metal-oxide-semiconductor NM2 is connected with power supply Vdd through resistance R 7, the source ground of metal-oxide-semiconductor NM2, and capacitor C 8 two ends are connected with drain electrode with the grid of metal-oxide-semiconductor NM2 respectively; The output of metal-oxide-semiconductor NM2 is connected with the grid of the second rank amplifier metal-oxide-semiconductor NM1 through capacitor C 9, and the drain electrode of metal-oxide-semiconductor NM1 is connected the source ground of metal-oxide-semiconductor NM1 through the inductance L 1 of series connection with resistance R 0 with power supply Vdd; Electric capacity R1 two ends are connected with drain electrode with the grid of metal-oxide-semiconductor NM1 respectively; Resistance R 2 two ends are connected with source electrode with the grid of metal-oxide-semiconductor NM1 respectively, and the grid of metal-oxide-semiconductor NM0 is connected back voltage Vbias for referencial use with drain electrode short circuit, the grid of metal-oxide-semiconductor NM0 with resistance R 8; Be connected with the grid of metal-oxide-semiconductor NM2; The drain electrode of metal-oxide-semiconductor NM0 is connected with power supply Vdd through resistance R 5, the source ground of metal-oxide-semiconductor NM0, and capacitor C 2 two ends are connected with source electrode with the grid of metal-oxide-semiconductor NM0 respectively.

In the wide band radio-frequency low noise amplifier of high-gain; Radiofrequency signal gets into the single order amplifier; The coupling of the inductance that equivalent series electric capacity, the resistance that adopts the Miller effect to produce is realized linking to each other with single order amplifier transistor grid is guaranteeing that high linearity carries out the part amplification under requiring.First rank have been introduced in mixed semiconductor's technology wide-band matching method commonly used-utilize the Miller effect and have been produced that equivalent series electric capacity comes with resistance and the inductance that is connected to the transistor gate level matees, and radiofrequency signal is tentatively amplified.This RCL cascaded structure can obtain desirable Broadband Matching, but therefore the quality factor q of circuit can reduce small inductor and a big electric capacity (capacitance depends on the center matching frequency) in the circuit about 1nH of existence.Because input stage has only been used a small inductor, so can reduce the area of LNA effectively.Can know that according to noise cascade formula the prime noise is maximum to the contribution of overall noise, so mainly come the noise of step-down amplifier here from several aspects such as raceway groove noise of source resistance, integrated inductor loss, transistor NM2.Further amplify radiofrequency signal on second rank, simultaneously the noise of rejective amplifier.Metal-oxide-semiconductor NM0, capacitor C 2, resistance R 5, the biasing circuit that R8 forms has determined the size of reference voltage, influences the working point and the gain of amplifier.

The detailed description of the wide band radio-frequency low noise amplifier that the present invention proposes is following:

The radio frequency amplifier that the present invention proposes comprises three parts: the first rank amplifying circuit, and second rank amplifying circuit and the biasing circuit, explain the concrete structure of each several part and annexation front, no longer repeats here.

The input compatible portion of LNA is extracted, and it is as shown in Figure 3 to turn to small-signal equivalent circuit.Gd1 looks back circuit from capacitor C, then the impedance of this part

$Z=\frac{s{R}_1(C_{\mathrm{gd}1}+C_{\mathrm{load}})+1}{s{C}_{\mathrm{gd}1}(s{R}_1{C}_{\mathrm{load}}+1+g_{m1}{R}_1)}$

$=\frac{C_{\mathrm{gd}1}+C_{\mathrm{load}}}{C_{\mathrm{gd}1}\·C_{\mathrm{load}}}\frac{s+\frac{1}{R_1(C_{\mathrm{gd}1}+C_{\mathrm{load}})}}{s(s+\frac{1+g_{m1}{R}_1}{R_1{C}_{\mathrm{load}}})}.---\left(1\right)$

Order

$A_v=1+g_{m1}{R}_1;a=\frac{1}{R_1(C_{\mathrm{gd}1}+C_{\mathrm{load}})}.$

$b=\frac{A_v}{R_1{C}_{\mathrm{load}}}.---\left(2\right)$

$C_{\mathrm{tot}}=\frac{C_{\mathrm{gd}1}+C_{\mathrm{load}}}{C_{\mathrm{gd}1}\·C_{\mathrm{load}}}.$

Then formula (1) can be reduced to

$Z=C_{\mathrm{tot}}\frac{s+a}{s(s+b)}$

$=\frac{1}{\frac{s}{C_{\mathrm{tot}}}+\frac{\text{1}}{\frac{C_{\mathrm{tot}}}{b-a}+\frac{a\·C_{\mathrm{tot}}}{s(b-a)}}}.---\left(3\right)$

Equivalent model is as shown in Figure 4, its impedance

$Z^{\′}=\frac{1}{\frac{s}{C_1}+\frac{1}{R+\frac{1}{s{C}_2}}}.---\left(4\right)$

Can find that Z ' has identical form with equality 3, so can make

$C_1=\frac{1}{C_{\mathrm{tot}}};R=\frac{C_{\mathrm{tot}}}{b-a};C_2=\frac{b-a}{a{C}_{\mathrm{tot}}}.---\left(5\right)$

Just can obtain input impedance Z _InExpression formula

$\mathrm{Zin}=\frac{1+s{C}_{2}R}{s(C_2+C_m)+s^2{C}_{2}R{C}_m}$

$\≈\frac{1+s{C}_{2}R}{s(C_2+C_m)}+\frac{C_{2}R}{C_2+C_m}.---\left(6\right)$

C wherein _m=C ₁+ C _Gs1So input matching network is only by L _g, C _gAnd R _gForm

$C_g=C_2+C_m=\frac{b-a}{a{C}_{\mathrm{tot}}}+\frac{1}{C_{\mathrm{tot}}}+C_{\mathrm{gs}1}---\left(7\right)$

＝A _vC _gd1+C _gs1.

$R_g=\frac{C_{2}R}{C_2+C_m}=\frac{R_1(1+\frac{C_{\mathrm{gd}1}}{C_{\mathrm{load}}})}{\frac{C_{\mathrm{gs}}}{C_{\mathrm{load}}}+A_v\frac{C_{\mathrm{gd}1}}{C_{\mathrm{load}}}}---\left(8\right)$

$\≈\frac{1+\frac{C_{\mathrm{load}}}{C_{\mathrm{gd}1}}}{g_m}.$

According to above-mentioned equality, can be through regulating R ₁, g _mAnd C _LoadTo C _Gd1Ratio make R _gNear 50 ohm, and C _gBe and C _Gs1The Miller effect electric capacity of parallel connection.

Be reduced to the small-signal equivalent model to the LNA two-stage circuit, shown in Fig. 5 (a), the gain expressions of the first order does

$G_{v1}=\frac{V_g}{V_s}\frac{s{C}_{\mathrm{gd}1}-g_{m1}}{s(C_{\mathrm{gd}1}+C_{\mathrm{load}})+1/R_1}---\left(9\right)$

$=\frac{R_g+1/s{C}_g}{R_g+1/s{C}_g+s{L}_g}\frac{s{C}_{\mathrm{gd}1}-g_{m1}}{s(C_{\mathrm{gd}1}+C_{\mathrm{load}})+1/R_1}.$

At the resonance frequency place

$G_{v1}=(1-\mathrm{jQ})\frac{(s{C}_{\mathrm{gd}1}-g_{m1})}{s(C_{\mathrm{gd}1}+C_{\mathrm{load}})+1/R_1}.---\left(10\right)$

Make Q=1, and ignore the influence of electric capacity, then the DC current gain in the equality 10

$G_{v1}=-\sqrt{2}{g}_{m1}{R}_1.---\left(11\right)$

Shown in Fig. 5 (b), partial gain expressions does

$G_{v2}=\frac{s{C}_{\mathrm{gd}2}+G_f-g_{m2}}{s(C_{\mathrm{gd}2}+G_f+C_L)+1/(R_2+s{L}_2)}---\left(12\right)$

$=\frac{-g_{m2}(R_2+s{L}_2)}{s{C}_L(R_2+s{L}_2)+1}.$

Can know that from equality 11 and equality 12 expression formula of the overall gain of LNA does

$G_v=G_{v1}{G}_{v2}$

$=\frac{\sqrt{2}{g}_{m1}{g}_{m2}{R}_1(R_2+s{L}_2)}{(1+\mathrm{sR}{C}_{\mathrm{load}})[s{C}_L(R_2+s{L}_2)+1]}.---\left(13\right)$

Can know according to noise cascade formula; The prime noise is maximum to the contribution of overall noise; So mainly consider several aspects such as raceway groove noise of source resistance, integrated inductor loss, transistor NM2 here; And after ignoring parameters such as bulk effect, channel length modulation effect, parasitic capacitance, obtain the expression formula of output noise

$\stackrel{\‾}{V_{n,\mathrm{out}}^2}=(\stackrel{\‾}{i_{n,R_1}^2}+\stackrel{\‾}{i_{n,M1}^2})R_2^2$

$+(\stackrel{\‾}{V_{n,R_s}^2}+\stackrel{\‾}{V_{n,L_g}^2}){\left(\sqrt{1+Q^2}{g}_{m1}{g}_{m2}{R}_1{R}_2\right)}^2---\left(14\right)$

$+\stackrel{\‾}{V_{n,R_1}^2}{\left(g_{m2}{R}_2\right)}^2.$

So the expression formula of noise factor F does

$F=[(\stackrel{\‾}{i_{n,R_2}^2}+\stackrel{\‾}{i_{n,M2}^2})R_2^2$

$+(\stackrel{\‾}{V_{n,R_s}^2}+\stackrel{\‾}{V_{n,L_g}^2}){\left(\sqrt{1+Q^2}{g}_{m1}{g}_{m2}{R}_1{R}_2\right)}^2$

$+(\stackrel{\‾}{v_{n,R_1}^2}+\stackrel{\‾}{i_{n,M1}^2}{R}_1^2){\left(g_{m2}{R}_2\right)}^2]$

$/\left[\stackrel{\‾}{v_{n,R_s}^2}{\left(\sqrt{1+Q^2}{g}_{m1}{g}_{m2}{R}_1{R}_2\right)}^2\right]$

$\≈1+\frac{R_g}{R_s}+\frac{R_1}{R_s}\frac{1}{(1+Q^2){\left(g_{m1}{R}_1\right)}^2}$

$+\frac{1}{3g_{m1}{R}_s}.$

Through each size of devices size correctly is set; Low noise amplifier of the present invention can be implemented in input coupling in the bandwidth of 2.3～3.8GHz＜-9.3dB; Power gain＞12.6dB; The index request of noise factor＜2.6dB, chip area are 0.356mm2, much smaller than traditional similar design.

Claims (1)

1. high-gain broadband radio-frequency low noise amplifier is characterized in that: radiofrequency signal is through the grid of inductance L 0 input metal-oxide-semiconductor NM2, and the drain electrode of metal-oxide-semiconductor NM2 is connected with power supply Vdd through resistance R 7; The source ground of metal-oxide-semiconductor NM2; Capacitor C 8 two ends are connected with drain electrode with the grid of metal-oxide-semiconductor NM2 respectively, and the output of metal-oxide-semiconductor NM2 is connected with the grid of the second rank amplifier metal-oxide-semiconductor NM1 through capacitor C 9, and the drain electrode of metal-oxide-semiconductor NM1 is connected with power supply Vdd with resistance R 0 through the inductance L 1 of series connection; The source ground of metal-oxide-semiconductor NM1; Resistance R 1 two ends are connected with drain electrode with the grid of metal-oxide-semiconductor NM1 respectively, and resistance R 2 two ends are connected with source electrode with the grid of metal-oxide-semiconductor NM1 respectively, the grid of metal-oxide-semiconductor NM0 and drain electrode short circuit; One end of resistance R 8 links to each other with the grid of metal-oxide-semiconductor NM0; The other end of resistance R 8 links to each other with reference voltage Vbias, and reference voltage Vbias is connected with the grid of metal-oxide-semiconductor NM2, and the drain electrode of metal-oxide-semiconductor NM0 is connected with power supply Vdd through resistance R 5; The source ground of metal-oxide-semiconductor NM0, capacitor C 2 two ends are connected with source electrode with the grid of metal-oxide-semiconductor NM0 respectively.

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