【正文】 大器電路原理框圖低噪聲放大器主要指標(biāo)是噪聲系數(shù)Ts ，其與源反射系數(shù)的關(guān)系如下：其中 電阻，Topt是最佳源反射系數(shù)。． 將影響放大器的穩(wěn)定性、噪聲系數(shù)、增益、駐波等參數(shù)。2 低噪聲放大器的設(shè)計(jì)理論圖1是放大器電路原理框圖，其中r 表示源反射系數(shù)，r 表示負(fù)載反射系數(shù)。Advanced Design System(ADS)軟件是Agilent公司在HPEESOF系列EDA軟件基礎(chǔ)上發(fā)展完善的綜合設(shè)計(jì)軟件，內(nèi)含很多進(jìn)行小信號(hào)放大器設(shè)計(jì)的控件，能實(shí)現(xiàn)大量的計(jì)算和smith圓圖分析?；贏DS仿真的低噪聲放大器設(shè)計(jì)類別：模擬技術(shù)1 引 言低噪聲放大器(LNA)位于射頻接收機(jī)的前端，其主要功能是對(duì)微弱信號(hào)進(jìn)行低噪聲放大。在低噪聲放大器的設(shè)計(jì)過(guò)程中，要綜合考慮其放大能力、噪聲系數(shù)和匹配等因素，這需要大量的理論計(jì)算和smith圓圖分析，給設(shè)計(jì)工作帶來(lái)困難。以下將介紹如何利用ADS設(shè)計(jì)和仿真低噪聲放大器。不同的r 和r。設(shè)計(jì)放大器的過(guò)程就是根據(jù)放大器的s參數(shù)，以及噪聲系數(shù)、增益、駐波等的要求來(lái)確定TS和TL，然后根據(jù)TS和TL確定輸入、輸出匹配網(wǎng)絡(luò)。當(dāng)Ts=Topt時(shí)，可以獲得最低噪聲系數(shù) NFmin。3 低噪聲放大器設(shè)計(jì)仿真和優(yōu)化3．1 設(shè)計(jì)目標(biāo)低噪聲放大器設(shè)計(jì)的關(guān)鍵是電路的第一級(jí)。利用ATF一33143完成電路第一級(jí)的設(shè)計(jì)目標(biāo)是：頻率：1260MHz一1280MHz；增益：≥10dB；噪聲系數(shù)：≤0．5dB；輸入駐波比：≤1．5；輸出駐波比：≤1．5。(2)確定工作點(diǎn)及偏置電路根據(jù)芯片在各直流工作點(diǎn)條件下的性能選擇直流工作點(diǎn)。在該直流工作點(diǎn)狀態(tài)下的芯片最小噪聲系數(shù)ⅣF i =0．34dB 。電路絕對(duì)穩(wěn)定的充要條件是Mu1和Mu—Prime1。反饋元件常用一段微帶線來(lái)代替，它相當(dāng)于電感性元件的負(fù)反饋。采取的改善穩(wěn)定性措施為：在芯片源極添加電感構(gòu)成負(fù)反饋；在漏極添加LRC串聯(lián)電路。電路在0．7GHz～3GHz頻率處于絕對(duì)穩(wěn)定狀態(tài)，而工作頻率為1260MHz一1280MHz，故滿足穩(wěn)定性要求。圖3 等噪聲系數(shù)圓控件和等增益圓控件圖4是等增益圓和等噪聲系數(shù)圓以Smith圓圖形式表示的仿真結(jié)果。增益為11dB。圖4 噪聲系數(shù)圓、等增益圓和輸入匹配點(diǎn)的確定(5)優(yōu)化在上述中，分別設(shè)計(jì)了直流偏置電路和輸入、輸出匹配網(wǎng)絡(luò)，但是輸入、輸出匹配網(wǎng)絡(luò)的加入會(huì)改變場(chǎng)效應(yīng)管的S參數(shù)，從而惡化某些指標(biāo)。首先選取優(yōu)化變量，設(shè)置變量的變化范圍，然后根據(jù)設(shè)計(jì)目標(biāo)設(shè)置仿真目標(biāo)，優(yōu)化仿真變量，得到達(dá)到預(yù)設(shè)目標(biāo)的最佳電路設(shè)計(jì)參數(shù)。圖5 優(yōu)化后的仿真結(jié)果4 結(jié)束語(yǔ)由仿真結(jié)果可知，所設(shè)計(jì)的低噪聲放大器在頻帶1260Mhz～1280MHz工作時(shí)，增益約為l1dB，輸入、輸出駐波均小于1．5，噪聲系數(shù)約為0．2dB，在1 GHz一3Ghz頻率范圍內(nèi)絕對(duì)穩(wěn)定，所有指標(biāo)均滿足設(shè)計(jì)要求。（英文版 ） easily blame, to prevent the broken window effect. Supervise the leading cadres to play an exemplary role, take the lead in the strict implementation of the code and rule , lead to safeguard the solemnity and authority of the party discipline, ensure that the party discipline and the laws and regulations for implementation in place. Throughout the discipline in the daily supervision and management, strengthen supervision and inspection, from the thorough investigation of violations of discipline behavior. Strengthen to key areas, key departments and key projects as well as the masses reflect the concentration of the units and departments for supervision. strengthening supervision, discipline inspection and supervision of cadres to set an example for pliance with the code and rule is a man must be hexyl, blacksmith needs its own hardware. Discipline inspection organs as the executor of the party discipline, and supervisor of the defenders, for its supervision must be more strictly, discipline inspection and supervision of cadres to firmly establish the awareness of Party Constitution, sense of discipline and rules consciousness, politics loyalty, sense obey. Action speak Ji Ordinance to set an example of the regulations of the rule of law, strengthen supervision and accept the supervision of the firmness and consciousness, do ply with and . To firmly establish the discipline must first be disciplined, the supervisor will be subject to the supervision of concept, and consciously safeguard and implement party passes party, take the lead in practicing three strict real strict, so loyal, clean, play. To be good at learning, the Constitution and the code as morality, politics and brought to fruition。 to discipline a ruler, often the control inspection, and consciously in the ideological red line to draw the row Ming Good accumulation is indeed the bottom line, so that the heart has fear, said to have quit, the line has ended. Attached: indifferent to heart, calmly to the table in our life, there are many unpredictable things will happen, some good, some bad things, we cannot control is powerless to stop, but with time, you will find in life sometimes turns out to be not good, some bad things finally turned out to be a good thing, but then we muddy however did not know, this is the life teach us things. 1, life can be plex, can also be simple. Want simple life of precipitation, to have enough time to reflect, to make Bee more perfect. Life is the most important thing is not to win, but the struggle。 not disillusioned after the heart, such as ashes, but experience the storm after the enlightenment。t always take everything back to things, and don39。t want to face, don39。 I am not afraid of the truth to tell the best friend, I39。t 6, when we are in a positive frame of mind, you will find many good things。 life happy and worry, all is you of life attitude, optimistic, good luck。 heart tired, calm. Grow up, mature, this society read. Tired and sad, squat down, to their a hug. Because the world no one can sympathize with you, have mercy on you. You cry, tears is your own。 now want anything, for fear that others know, or like to lose the same. 9, the heart move, everything in the world is followed by birth, Rangrang, important thing is often the most difficult to open one39。 to let strangers people care about your life in the good things, the original is not easy 10, do not blame, do not laugh at who, also don39。 no matter how many grievances, how unfortable, and ultimately to heal themselves or their own, others may got you to fort, but never know your heart is how wanjianchuanxin. 12, ma39。 and an exception is better to give than to what 13, don39。t lose your life and the life, respectively is: the former is a we experienced cannot escape in a day finally will last minute, while the latter is our persistent, we want to cherish the memory of those people and things. 14, learn to smile, learn to strong, the world you know so many people, so many people and you are, you cannot change also can39。 you learn knowledge, is you have weapons, you can start from scratch, but not unarmed。 to be alive, you will have trouble. Life is the most afraid of what all want to care about, but also what all grasp is not firm, without scenery, separated populations, such as not to desire, all docked in the fate of the end. Why is too rigid, the natural, to go stay not to live, let go of obsession, revel is 20, if the fate of the broken Hopes of sailing, please don39。t helpless, because they are still alive, is still a dream, the sun still, we still. Lost, keep memories。 but the most important is good to cherish their own. 21, life, select the plex, is to choose the pain。t mis