CN104158610B - Receiver mixer output response modeling method - Google Patents

Abstract

Receiver mixer output response modeling method, comprises the steps: 1) obtain the local oscillator end signal of frequency mixer, radio-frequency head signal, local oscillator end leak into the signal of intermediate frequency end, radio-frequency head leaks into the signal of intermediate frequency end；2) local oscillator end signal and the product of radio-frequency head signal, local oscillator end are leaked into the signal of intermediate frequency end, radio-frequency head leaks into the signal three summation of intermediate frequency end, obtains the output response of receiver mixer.The present invention has considered the radio-frequency head of frequency mixer and has born three kinds of nonlinear effect factors such as gain transfer effect, local oscillator end switch effect and port effects of coupling between, it is calculated frequency mixer output response by known quantities such as frequency mixer performance parameter, input signals, ensure frequency mixer Nonlinear Modeling precision, Accurate Prediction and calculating receiver mixer nonlinear object response characteristic under interference environment.

Description

Receiver mixer output response modeling method

Technical field

The invention belongs to electromagnetic interference predictive simulation technical field, be specifically related to a kind of receiver mixer output response and build Mould method, for calculating receiver mixer output response characteristic under interference environment.

Background technology

The electronic equipment such as radar, communication is in when working under interference environment, and the frequency mixer of receiver is often in non-linear sound Answer state, more interfering frequency composition can be produced, affect the performance of late-class circuit.Clear and definite receiver is not yet had to be mixed at present Device nonlinear response model, it is impossible to accurately calculate frequency mixer output response under interference environment.Connect for Accurate Prediction and calculating Receipts machine frequency mixer non-linear response characteristic under interference environment, needs the foundation can the non-linear sound of accurate description receiver mixer Answer the computation model of characteristic.Three kinds of nonlinear effect factors such as negative gain transfer, switching effect and port coupling effect are mixing The build-in attribute of device, has embodiment in the measured data of frequency mixer output response, therefore, for ensureing frequency mixer Nonlinear Modeling essence Degree need to consider above-mentioned three kinds of nonlinear effect factors.

Summary of the invention

The technical problem to be solved in the present invention is, for existing receiver mixer response model above shortcomings, There is provided a kind of receiver mixer output response modeling method, this modeling method considered frequency mixer bear gain transfer, Three kinds of nonlinear effect factors such as switching effect and port coupling effect, can be used for calculating receiver mixer under interference environment Output response.

The present invention solves that above-mentioned technical problem be the technical scheme is that

The modeling method of receiver mixer output response, comprises the steps:

1) obtain the local oscillator end signal of frequency mixer, radio-frequency head signal, local oscillator end leaks into the signal of intermediate frequency end, radio-frequency head is let out Drain to the signal of intermediate frequency end；

2) local oscillator end signal and the product of radio-frequency head signal, local oscillator end are leaked into the signal of intermediate frequency end, radio-frequency head leakage Signal three to intermediate frequency end sues for peace, and the output obtaining receiver mixer responds:

S_IF(t)=S_LO(t)·S_RF(t)+S_LO-IF(t)+S_RF-IF(t) (1)

Wherein, S_IFT () is the output response of receiver mixer, S_LOT () is local oscillator end signal, S_RFT () is radio-frequency head letter Number, S_LO-IFT () is the signal that local oscillator end leaks into intermediate frequency end, S_RF-IFT () is the signal that radio-frequency head leaks into intermediate frequency end.

By such scheme, described local oscillator end shows as switching characteristic, local oscillator end signal S_LOT () uses odd harmonic multinomial Model taking after 5 subharmonic block is expressed as

$S_{\mathrm{LO}}\left(t\right)=A\·(\cos (2\mathrm{\π}\·f_{\mathrm{LO}}\·t)+\frac{1}{3}\·\cos (2\mathrm{\π}\·3f_{\mathrm{LO}}\·t)+\frac{1}{5}\·\cos (2\mathrm{\π}\·{5f}_{\mathrm{LO}}\·t))---\left(2\right)$

Wherein, f_LOFor local oscillator end signal frequency (f_LOAs frequency mixer running parameter, frequency mixer device unit provide, The amount of knowing), A is fundamental voltage amplitude, and the relational representation between fundamental voltage amplitude A and local oscillator end signal power is

$A=\sqrt{{2R}_L\·{10}^{{0.1P}_{\mathrm{dBm}}-3}}---\left(3\right)$

Wherein, P_dBmFor the local oscillator end signal power (P using dBm form to represent_dBmAs frequency mixer performance parameter by being mixed Device device unit provides, it is known that amount), R_LFor load resistance.

By such scheme, described radio-frequency head signal S_RFT () is that radio-frequency head is born gain output signal and leaked into local oscillator end and penetrate Frequently the signal sum of end:

S_RF(t)=y (t)+S_LO-RF(t) (4)

Wherein, y (t) is that radio-frequency head bears gain output signal, S_LO-RFT () is the signal that local oscillator end leaks into radio-frequency head；

I () described radio-frequency head is born gain output signal y (t) and is used three rank multinomial models to calculate, and by many for three rank Even order components in item formula model filters through rear class filter circuit, and the expression formula obtaining three rank multinomial models is as follows:

y(t)≈a₁x(t)+a₃x³(t) (5)

Wherein, x (t) is input signal, and a1 is the linear term coefficient of output signal y (t), and a1 is expressed as

a₁=10^G/20 (6)

Wherein, G be use the frequency mixer that represents of dB form bear gain (G as frequency mixer performance parameter by frequency mixer device Unit provides, it is known that amount)；

a₃For three rank term coefficient of output signal y (t), a₃It is expressed as

$a_3=-\frac{{{2a}_1}^3}{{3R}_L\·{10}^{{0.1P}_{I3}-3}}---\left(7\right)$

Wherein, P_I3For the third order intermodulation point (P using dBm form to represent_I3As frequency mixer performance parameter by frequency mixer device Part unit provides, it is known that amount)；

(ii) described local oscillator end leaks into the signal S of radio-frequency head_LO-RFT () is expressed as

$S_{\mathrm{LO}-\mathrm{RF}}\left(t\right)=S_{\mathrm{LO}}\left(t\right)/{10}^{{\mathrm{dB}}_{\mathrm{LO}-\mathrm{RF}}/20}---\left(8\right)$

Wherein dB_LO-RFFor using the local oscillator end that represents of dB form to the degree of coupling (dB of radio-frequency head_LO-RFAs frequency mixer Can parameter be provided by frequency mixer device unit, it is known that amount).

By such scheme, described local oscillator end leaks into the signal S of intermediate frequency end_LO-IFT () is expressed as

$S_{\mathrm{LO}-\mathrm{IF}}\left(t\right)=S_{\mathrm{LO}}\left(t\right)/{10}^{{\mathrm{dB}}_{\mathrm{LO}-\mathrm{IF}}/20}---\left(9\right)$

Wherein, dB_LO-IFFor using the local oscillator end that represents of dB form to the degree of coupling (dB of intermediate frequency end_LO-IFAs frequency mixer Can parameter be provided by frequency mixer device unit, it is known that amount).

By such scheme, described radio-frequency head leaks into the signal S of intermediate frequency end_RF-IFT () is expressed as

$S_{\mathrm{RF}-\mathrm{IF}}\left(t\right)=S_{\mathrm{RF}}\left(t\right)/{10}^{{\mathrm{dB}}_{\mathrm{RF}-\mathrm{IF}}/20}---\left(10\right)$

Wherein dB_RF-IFFor using the radio-frequency head that represents of dB form to the degree of coupling (dB of intermediate frequency end_RF-IFAs frequency mixer Can parameter be provided by frequency mixer device unit, it is known that amount).

The operation principle of the present invention: according to above procedure, it is considered to radio-frequency head bears gain transfer effect, local oscillator end switch effect And the nonlinear effect such as port effects of coupling between, the known quantities such as frequency mixer performance parameter, input signal it is calculated mixing Device output response.

The beneficial effects of the present invention is: this receiver mixer output response modeling method has considered frequency mixer and born Three kinds of nonlinear effect factors such as gain transfer, switching effect and port coupling effect, it is ensured that frequency mixer Nonlinear Modeling precision, Accurate Prediction and calculating receiver mixer nonlinear object response characteristic under interference environment, improve late-class circuit performance.

Detailed description of the invention

Below in conjunction with embodiment, the present invention is described in detail.

As a example by certain receiver mixer, its important technological parameters: frequency mixer bears gain G for-6dB, third order intermodulation point P_I3 For 30dBm, degree of coupling dB of local oscillator end to intermediate frequency end_LO-IFFor 20dB, degree of coupling dB of radio-frequency head to intermediate frequency end_RF-IFFor 20dB, Local oscillator end is to degree of coupling dB of radio-frequency head_LO-RFFor 30dB.Main input parameter: local oscillator end signal power P_dBmFor 30dBm, local oscillator End signal frequency f_LOFor 800MHz, load resistance R_LIt is 50 Ω.

According to load resistance R_L, local oscillator end signal power P_dBmAnd formula (3) obtains fundamental voltage amplitude A=10；

According to fundamental voltage amplitude A, local oscillator end signal frequency f_LOAnd formula (2) obtains local oscillator end signal S_LO(t) be

$S_{\mathrm{LO}}\left(t\right)=10\·(\cos (2\mathrm{\π}\·800\·{10}^6\·t)+\frac{1}{3}\·\cos (2\mathrm{\π}\·3\·800\·{10}^6\·t)+\frac{1}{5}\·\cos (2\mathrm{\π}\·5\·800\·{10}^6\·t))---\left(11\right)$

Gain G, load resistance R is born according to frequency mixer_L, third order intermodulation point P_I3And formula (4)～formula (7), obtain radio-frequency head Signal S_RF(t) be

$S_{\mathrm{RF}}\left(t\right)={10}^{-0.3}\·x\left(t\right)-\frac{{2\·10}^{-0.9}}{150}\·x^3\left(t\right)+S_{\mathrm{LO}-\mathrm{RF}}\left(t\right)---\left(12\right)$

Degree of coupling dB according to local oscillator end to radio-frequency head_LO-RFAnd formula (8), obtain local oscillator end and leak into the signal of radio-frequency head S_LO-RF(t) be

S_LO-RF(t)=S_LO(t)/10^-0.3 (13)

Degree of coupling dB according to local oscillator end to intermediate frequency end_LO-IFAnd formula (9), obtain local oscillator end and leak into the signal of intermediate frequency end S_LO-IF(t) be

S_LO-IF(t)=S_LO(t)/10 (14)

Degree of coupling dB according to radio-frequency head to intermediate frequency end_RF-IFAnd formula (10), obtain radio-frequency head and leak into the letter of intermediate frequency end Number S_RF-IF(t) be

S_RF-IF(t)=S_RF(t)/10 (15)

Equation (12)～equation (15) are substituted into equation (1), obtains the output response S of receiver mixer_IFT () is (the most mixed Device response model needs intermediate frequency end signal frequently that solve) be

$S_{\mathrm{IF}}\left(t\right)=[S_{\mathrm{LO}}\left(t\right)+0.1]\·[{10}^{-0.3}\·x\left(t\right)-\frac{{2\·10}^{-0.9}}{150}\·x^3\left(t\right)+S_{\mathrm{LO}}\left(t\right)/{10}^{-0.3}]+S_{\mathrm{LO}}\left(t\right)/10---\left(16\right)$

Local oscillator end signal S_LOT () and input signal x (t) are all known quantities, thus can solve the output in formula (17) and ring Answer S_IF(t)。

Such as, it is the typical linear FM signal as described in following formula for input signal x (t):

$x\left(t\right)=\cos (2\mathrm{\πft}+\mathrm{\π}\frac{B}{\mathrm{\τ}}{t}^2)---\left(17\right)$

Wherein, f is the carrier frequency of input signal, and B is the bandwidth of input signal, and τ is the pulse width of input signal；

The output response S obtaining receiver mixer is solved according to equation (16)_IF(t)。

The above-described presently preferred embodiments of the present invention that is only, can not limit the right model of the present invention with this certainly Enclose, the equivalence change therefore made according to scope of the present invention patent, still belong to protection scope of the present invention.

Claims (1)

1. the modeling method of receiver mixer output response, it is characterised in that comprise the steps:

1) obtain the local oscillator end signal of frequency mixer, radio-frequency head signal, local oscillator end leaks into the signal of intermediate frequency end, radio-frequency head leaks into The signal of intermediate frequency end；

2) local oscillator end signal and the product of radio-frequency head signal, local oscillator end are leaked into the signal of intermediate frequency end, during radio-frequency head leaks into Frequently the signal three summation of end, the output obtaining receiver mixer responds:

S_IF(t)=S_LO(t)·S_RF(t)+S_LO-IF(t)+S_RF-IF(t) (1)

Wherein, S_IFT () is the output response of receiver mixer, S_LOT () is local oscillator end signal, S_RFT () is radio-frequency head signal, S_LO-IFT () is the signal that local oscillator end leaks into intermediate frequency end, S_RF-IFT () is the signal that radio-frequency head leaks into intermediate frequency end；

Described local oscillator end signal S_LOT () uses odd harmonic multinomial model taking after 5 subharmonic block to be expressed as

$S_{LO}\left(t\right)=A\·\left(cos\right(2\mathrm{\π}\·f_{LO}\·t)+\frac{1}{3}\·cos(2\mathrm{\π}\·3f_{LO}\·t)+\frac{1}{5}\·cos(2\mathrm{\π}\·5f_{LO}\·t\left)\right)---\left(2\right)$

Wherein, f_LOFor local oscillator end signal frequency, A is fundamental voltage amplitude, between fundamental voltage amplitude A and local oscillator end signal power Relational representation be

$A=\sqrt{2R_L\·{10}^{0.1P_{dBm}-3}}---\left(3\right)$

Wherein, P_dBmFor the local oscillator end signal power using dBm form to represent, R_LFor load resistance；

Described radio-frequency head signal S_RFT () is that radio-frequency head is born gain output signal and local oscillator end and leaked into the signal sum of radio-frequency head:

S_RF(t)=y (t)+S_LO-RF(t) (4)

Wherein, y (t) is that radio-frequency head bears gain output signal, S_LO-RFT () is the signal that local oscillator end leaks into radio-frequency head；

I () described radio-frequency head is born gain output signal y (t) and is used three rank multinomial models to calculate, and by three rank multinomials Even order components in model filters through rear class filter circuit, and the expression formula obtaining three rank multinomial models is as follows:

y(t)≈a₁x(t)+a₃x³(t) (5)

Wherein, x (t) is input signal, a₁For the linear term coefficient of output signal y (t), a₁It is expressed as

a₁=10^G/20 (6)

Wherein, G is that gain born by the frequency mixer using dB form to represent；

a₃For three rank term coefficient of output signal y (t), a₃It is expressed as

$a_3=-\frac{2{a_1}^3}{3R_L\·{10}^{0.1P_{I3}-3}}---\left(7\right)$

Wherein, P_I3For the third order intermodulation point using dBm form to represent；

(ii) described local oscillator end leaks into the signal S of radio-frequency head_LO-RFT () is expressed as

$S_{\mathrm{LO}-\mathrm{RF}}\left(t\right)=S_{\mathrm{LO}}\left(t\right)/{10}^{d{B}_{\mathrm{LO}-\mathrm{RF}}/20}---\left(8\right)$

Wherein dB_LO-RFFor using the local oscillator end that represents of dB form to the degree of coupling of radio-frequency head；

Described local oscillator end leaks into the signal S of intermediate frequency end_LO-IFT () is expressed as

$S_{LO-IF}\left(t\right)=S_{LO}\left(t\right)/{10}^{{\mathrm{dB}}_{LO-IF}/20}---\left(9\right)$

Wherein, dB_LO-IFFor using the local oscillator end that represents of dB form to the degree of coupling of intermediate frequency end；

Described radio-frequency head leaks into the signal S of intermediate frequency end_RF-IFT () is expressed as

$S_{RF-IF}\left(t\right)=S_{RF}\left(t\right)/{10}^{{\mathrm{dB}}_{RF-IF}/20}---\left(10\right)$

Wherein dB_RF-IFFor using the radio-frequency head that represents of dB form to the degree of coupling of intermediate frequency end.