TWI418802B - 用於儀表系統之綜合前端 - Google Patents

用於儀表系統之綜合前端 Download PDF

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TWI418802B
TWI418802B TW098123078A TW98123078A TWI418802B TW I418802 B TWI418802 B TW I418802B TW 098123078 A TW098123078 A TW 098123078A TW 98123078 A TW98123078 A TW 98123078A TW I418802 B TWI418802 B TW I418802B
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input
gain
amplifier
current
circuit
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TW201009354A (en
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Barrie Gilbert
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Analog Devices Inc
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Description

用於儀表系統之綜合前端
本明係為用於儀表系統之綜合前端。
 具電流模式輸入端、寬廣範圍之偏移量注入、及串級增益階段之示波器前端
第1圖顯示先前技術示波器輸入電路。該輸入信號係經由傳統BNC連接器施加至單一增益緩衝器放大器，其典型具有FET輸入階段。該輸入信號係由一1MΩ對地電阻器其提供經界定的輸入阻抗而終結。由於緩衝放大器直接測量跨終端電阻器之電壓，故第1圖電路可經決定其特徵為電壓模式電路。
使用FET放大器之原因在於其具有高靈敏度及高輸入阻抗，通常係當試圖測量高頻、低位準信號時為有利。但此種靈敏度使其對暫態及過載狀況易感。由於示波器係用於研究、開發、測試等，就定義上，示波器係連接至具有未知參數的信號源。此種信號源可施加以千伏特(kV)為單位測量之暫態電壓，以及其它類型之延長過載至輸入電路。因此，於輸入放大器前方須含括一暫態/過載保護電路。但保護電路複雜且價昂。實際上，保護電路所耗用的成本和空間傾向於超過實際輸入測量電路所耗用的成本和空間。此外，保護電路容易干擾測量電路之正常操作。
依據本發明之一實施例，係特地提出一種用於一儀表系統之輸入階段，該輸入階段包含：接收欲測量之一信號之一輸入終端；一加法節點；耦接於該輸入終端與該加法節點間之一電阻器；及設置來維持於該加法節點之電壓之一放大器。
 較佳實施例之詳細說明
第2圖顯示根據本專利案揭示之發明原理用於示波器之輸入電路之一實施例。輸入信號係施加至相對大數值的輸入電阻器(例如1MΩ)之一端。但該輸入電阻器之另一端係連接至於該放大器之反相(-)輸入端之一加法節點。如此，輸入信號即刻變換成電流，該電流繼續流經一回授電阻器，為求方便該電阻器也假設為1MΩ。
輸入至第2圖所示配置之輸入信號固有地限流，其提供高度保護免於暫態及過載情況。額外保護係由跨放大器之輸入端連接的、背對背二極體，較佳為蕭特基二極體提供。輸入電阻器及/或額外補償電容器及RC網路可實施為單晶片或外部組件。
使用多種技術，經由將偏移量信號注入加法節點可提供回軌(slideback，偏壓補償)特徵，其可維持於虛擬地電位。例如偏移量可由第2圖所示可變電流源提供，及/或回軌特徵可藉施加一數位字元至一數位至類比變換器實施，該變換器然後經由另一電阻器將該偏移量注入該加法節點。第2圖之配置可提供寬廣範圍之偏移量，其特別可用於實施示波器之回軌特徵來允許使用者觀看載波於遠較大的DC(或準DC或脈衝)信號位準上的小信號細節之精細位準。
第3圖顯示根據本專利案揭示之發明原理用於示波器之輸入電路之一實施例之若干可能的實施細節。電阻器R1將輸入信號變換成於加法節點N1之電流。輸入放大器包括JFET輸入電晶體Q1及Q2，其驅動差動對Q3及Q4，而其又經由疊接電晶體Q5及Q6驅動射極隨耦器Q7及Q8。如此，單端輸入信號於OUTP及OUTM被變換成良好平衡的完全差動輸出信號用以藉隨後階段進一步處理。於加法節點N1之終端SB提供用以注入回軌操作之偏移量信號之方便點。第3圖電路之另一特性為不具有顯著熱尾。換言之，當輸入信號被過驅時，電路快速復原，而當過載被移除時，不具有顯著過衝或下衝。
輸入電阻器R1組合回授電阻器R2設定總增益。R1及R2值可設定為最終期望值，或可製造來協助使用者調整性。舉例言之，若R1及R2為1.5MΩ，則使用者可跨INP與SB終端以及OUTP與SB終端連結適當電阻器，來準確微調輸入電阻至1MΩ或用於示波器之輸入端為方便的其它數值，同時仍然維持正確增益。
電容器C2提供回授補償。電容器C1顯示作為可變電容器，其可經微調來調整HF補償，例如作為單次(one-time)單晶片調整。額外補償係由R3及C3提供，其可為單晶片組件、外部組件、或單晶片組件與外部組件的組合。
第4圖顯示根據本專利案揭示之發明原理用於示波器前端之一新穎架構。本實例中，目標係提供以0.01分貝增量之40分貝增益。但其原理並未囿限說明書的此等實例。反而試圖以單一可變增益放大器(VGA)提供整個增益範圍，該增益範圍分解成數個串級階段。本實例中，可變增益係由三個中間階段提供，各個階段具有前方有個數位選擇性可變衰減器之一固定式增益主放大器。固定式增益輸入階段及固定式增益輸出階段前方有一可變衰減器來完成該信號路徑。
此種配置有若干優勢。第一，示波器輸入信號要求高的總頻寬。VGA分解成數個階段，允許該系統具有比較否則於單一階段所能達成之產物，更高增益頻寬的產物。第二，經由配置該等增益階段，故隨著增益的增加可被激勵，可達成比較單一VGA階段更佳的信號對雜訊比(SNR)。
第三，經由分裂VGA成多個階段，更容易允許各個階段對其特定任務為最佳化，甚至於第4圖所示多晶片配置中使用不同的半導體技術亦如此。舉例言之，輸入階段可於GaAs晶片上實施，而其它階段係於矽晶片實施，而全部晶片皆係安裝於單一頭座上。但全部階段皆可製作於單一晶片上，而多種其它配置亦屬可能。至於又一實例，輸出階段可對用於驅動A/D變換器最佳化。進一步，將VGA分裂成多個階段，允許定位增益選擇功能為最有利之處。本實例中，可變增益係由三個中間階段提供，但可變增益功能另外或此外可位於輸入階段、輸出階段等。此外，粗、中、及細增益增量可以任一種適當方式分布；例如，粗增益位於三個中間階段之中央者，中增益位於三個中間階段之第一者，而細增益位於三個中間階段之最末者。前文討論之電流模式輸入階段特別可優異地用作為輸入階段。
第四，來自於同時示波器中之類比前端電路的輸出信號一成不變地耦接至A/D變換器用於進一步處理且顯示於數位域。A/D變換器要求於輸入端之抗頻疊濾波器用以獲得適當操作，通常以較高階濾波器為佳。相當容易於個別階段含括較低階濾波器，因此藉由將多個增益階段串級在一起，總體結果為獲得用於抗頻疊目的為理想的極高階濾波器。
具低慣量轉向之可變增益放大器
第5圖顯示先前技術可變增益放大器(VGA)，其中輸入信號VIH 、VIL 係施加至有多個輸出分接點的衰減器之輸入端，且連續插補的跨導(gm)階段係用來將輸出信號從一個或多個選定的分接點轉向至主放大器。此種大致配置稱作為X-AMP，且有多種變化，包括此處顯示的差動版本及單端版本。gm階段係藉一系列插補器電流控制，該等電流通常係呈重疊高斯電流脈衝形式，其漸進地順著衰減器之縱向，允許gm階段可動作與不允許動作來沿著衰減器轉向輸出信號，因而改變增益。
於若干應用中，例如示波器前端，VGA須對低增益及高頻寬為最佳化。使用X-AMP，將涉及增加gm胞元中的電晶體尺寸。但加大電晶體尺寸造成額外問題，諸如與各個接面相關聯之電容增加。如此導致高頻電流之饋穿(或洩漏)通過gm胞元，此種程序偶爾稱作為「漏電流」。所得結構變笨重且效果不彰。
第6圖顯示根據本專利案揭示之發明原理VGA電路之一實施例。經由以低慣量開關諸如絕緣體上矽(SOI)電晶體置換gm胞元，可達成高頻寬操作而無顯著有害效應，諸如饋穿。此外，SOI電晶體可以飽和操作來提供極低on電阻，但末造成大型基質電流，原因在於於NPN開關之情況下，並未關聯基質PNP。
如第6圖所示，輸入信號係施加至具有共用模式終端ACM之一差動衰減器的輸入端INP、INM。成對SOI電晶體Q1、Q1’至Q4、Q4’係配置來將該信號從成對分接點轉向至連結至OPP及OPM之主放大器。轉向電晶體係藉可由任何適當來源所產生之可規劃選擇電流I1、I1’至I4、I4’驅動。本實例中，選擇電流係由電流源電晶體Q5、Q5’至Q8、Q8’回應於增益選擇信號S1-S4而產生。基極電阻器RB防止來自於電流源電晶體的任何漏電流啟動轉向電晶體。轉向電晶體的基極當為off時，另外可直接連結至某一型地電位節點，但使用基極電阻器可能足以防止任何信號的傳送至輸出端。又另外，基極電阻器之其它端可接地，但如此可能造成基極電阻器變成衰減器之一部分，特別係朝向輸出端。
第6圖之電路提供比較使用gm胞元所能達成者之一總體較低慣量系統，且進一步，主放大器現在可實施為低雜訊放大器(LNA)。差動結構協助抵消由開關及相關聯之支援電路所造成的偏位，以及因開關的on電阻低，故雜訊低。
第6圖之電路也可實施為只有單一系列低慣量開關的單端電路。轉向動作可為連續，亦即插置於分接點間，或可使用介於分接點間的分開切換。衰減器係顯示為梯階型網路，但可利用其它類型多重分接衰減器網路。
主放大器
第7圖顯示根據本專利案揭示之發明原理用於具有可變衰減器前端之VGA之主放大器之一實施例。第7圖之實施例係顯示為單端電路，但本發明原理也預期涵蓋差動實施例。輸入信號施加至藉尾電流IT 施加偏壓之gm胞元之一個輸入端。該gm胞元係經由一疊接階段而負載低雜訊電流源I1 及I2 。差動放大器10具有一差動輸入端連結至來自於疊接階段的輸出端各側。該輸出端係經由設定總放大器增益的回授網路R1、R2而耦接回該gm胞元的另一個輸入端。
疊接階段減少gm胞元內該等電晶體間的功率耗散變化，因而最小化暫態熱效應。舉例言之，於施加至gm胞元的輸入信號偏移一個極性期間，該gm胞元的一側將攜載較多電流。疊接階段協助提高gm胞元另一側的電壓，使得藉該gm胞元另一側耗散的功率(藉電壓與電流的乘積測定)更接近等於藉該gm胞元之第一側所耗散的功率。疊接電晶體之偏壓或錨定電壓可設定為一電壓，該電壓係經實驗測定可環繞位移該功率耗散來提供適當熱效應。
電容器C2於閉環頻率響應形成第一極(或主極)，而電容器C1於閉環頻率響應形成第二極(或輔極)。該等電容器可實施為交換電容器或可變電容器，而尾電流IT 可變更來提供整合型濾波器控制，容後詳述。
第7圖之主放大器可用於任何適當輸入裝置，包括任一型可變衰減器輸入裝置，但特別為如前文說明之具有低慣量轉向之衰減器之輸入裝置。
具整合型濾波器控制之放大器
可變增益放大器常用作為A/D變換器的輸入裝置。典型要求抗頻疊濾波器係介於該放大器與A/D變換器間。先前技術配置利用分開的抗頻疊濾波器，造成系統的成本與複雜度的增高。
若干額外本專利案揭示之發明原理係有關具有低通濾波器之放大器，該等濾波器係與主放大器整合且提供寬廣調整範圍。該拓樸結構允許藉切換不同電容器數值(例如用於粗調)、及藉改變通過主放大器之偏壓電流(例如用於細調)而達成極所在位置的調整。
濾波器與主放大器整合提供簡化且緊密整合的解決之道。此外，若此整合型低通濾波器配置係利用於一系列串級增益階段，則可實現有極多個極的抗頻疊濾波器，原因在於多個增益階段各自貢獻一極或二極予總濾波操作。又，電路拓樸結構允許使用低回動電流鏡(又稱V鏡)作為主放大器上的負載，藉此提供極高準確度。
第8圖顯示根據本專利案揭示之發明原理具有整合型濾波器控制之放大器之一實施例。第8圖之實施例係基於第7圖之拓樸結構，但此處該等電容器係連結於信號路徑的一側與一共用點間來協助不同的電容器值之切換。gm胞元現在藉電流鏡攜載，而輸出信號係自電流鏡之一側輸出且施加至一緩衝放大器12。
濾波器控制可藉多項技術提供。第一，電容器值可切換而改變低通濾波器角頻率。第二，電容器值可切換來改變系統之Q。第三，尾電流IT 可變更來提供額外控制程度，原因在於改變尾電流可改變gm胞元之電晶體之re，其變更角頻率。如此可用作為例如精細控制來內插於電容器各階級間。藉由將電容器連結拉出IC上的端子，電容器可從外部切換，或藉使用內部開關諸如SOI開關切換。
第9圖顯示根據本專利案揭示之發明原理之放大器之另一實施例。第9圖之實施例完全以一共用終端ACM為中心差動，該ACM可設定作為AC共用模式節點。gm胞元Q1-Q4及Q5-Q8係實施為藉電流源IT1-IT4施加偏壓之多雙曲正切胞元。疊接電晶體Q9、Q10、Q9’、Q10’係錨定於偏壓電壓VB。電流鏡14及16係實施為V鏡，如下所示。
於電路上半部，緩衝放大器係由射極隨耦器電晶體Q11及Q12形成，其係藉尾電流IT6施加偏壓且提供輸出端OPP。電晶體Q13及Q14於電路下半部形成緩衝電路且藉電流IT7施加偏壓。電阻器R1-R4形成增益設定回授網路。當緩衝放大器實施為射極隨耦器時，V鏡的使用特別有利，原因在於例如Q11基極的電壓於操作期間須顯著改變。於其它型電流鏡之輸入端之此種電壓擺動可能造成操作不準確。但V鏡可減少此項效應。
切換式電容器網路或以其它方式可選擇之電容器網路18、20、22及24提供可調整式多極濾波器控制。電容器網路之共用端可連結至該共用模式終端ACM或任何其它適當點。
於電路之上半部，電容器網路20與gm胞元之射極電阻共同工作而形成一第一極。第二電容器網路18形成第二極，該第二極可於第一極之相同頻率，但非於原點。如此，第一極呈1/sT1 形式，而第二極呈1/(1+sT2 )形式。如此，總開環響應為1/[sT1 (1+sT2 )]，各極係於s平面環繞移動而提供適當響應。於電路下半部的電容器網路提供類似效應。
電路各側也提供額外射極隨耦器階段。於上半部，此乃電晶體Q15其係連結至來自Q11之電流鏡負載之對側。電晶體Q15主要由R15載荷，R15調整為粗略等於載荷Q11的R11。藉由連結射極隨耦器至電流鏡兩側，由於兩側顯示來自於射極隨耦器之類似效應，故減低差動電流。也含括電阻器R17及R18來交叉耦合Q15及Q16之輸出端至電路相對兩側提供基極電流及獨特補償方案，該補償方案可使用V鏡協助。
第10圖顯示V鏡之一般實施例。此型電流鏡之大致操作係說明於美國專利案第6,437,630號，發明人同本案，以引用方式併入此處。第11圖顯示根據本專利案揭示之發明原理適合用於放大器之V鏡之一實施例。
當前文說第7圖至第11圖說明之發明原理結合多階段前端系統諸如前文於第4圖所示系統使用時，其提供順著信號鏈的進行性濾波，符合非線性假信號之減至最低。濾波器可實施為純粹RC型，而非gm/C拓樸結構之某個變化結構俾便減少頻帶外失真(因大的高頻信號造成交互調變之假信號)。若用於第4圖之實施例，兩個階段提供可規劃共軛極對、或總四極響應。全部設定值中，響應可於時域調整為最大平坦。
前文說明之原理特別可用於儀表系統之類比前端，諸如示波器或超音波系統，此處其協力工作來提供調整適應該系統之獨特特性的綜合解決辦法。雖言如此，該等原理也可分開利用且應用於其它用途。
10．．．差動放大器
12．．．緩衝放大器
14．．．電流鏡
16．．．電流鏡
18、20、22、24．．．電容器網路
ACM．．．共用模式終端
C1-C3．．．電容器
Q1-Q16、Q1’-Q10’．．．電晶體
R1．．．輸入電阻器
R2．．．回授電阻器
Q1、Q2．．．JFET輸入電晶體
Q3、Q4．．．差動對電晶體
Q5、Q6．．．疊接電晶體
Q7、Q8．．．射極隨耦器電晶體
I1 、I2 ．．．低雜訊電流源
IT1-IT7．．．電流源
IT ．．．尾電流
INP．．．差動衰減器之輸入端
INM．．．差動衰減器之輸入端
I1-I4、I1’-I4’．．．可規劃選擇電流
N1．．．加法節點
NPN．．．開關
OPP．．．輸出端
OPM．．．輸出端
Q5-Q8、Q5’-Q8’．．．電流源電晶體
LNA．．．低雜訊放大器
OUTP．．．終端
SB．．．終端
VB．．．偏壓電壓
N1．．．節點
PNP．．．基質
R1-R18．．．電阻器
S1-S4．．．增益選擇信號
RB．．．基極電阻器
LNA．．．低雜訊放大器
第1圖顯示先前技術示波器輸入電路。
第2圖顯示根據本專利案揭示之發明原理用於示波器之輸入電路之一實施例。
第3圖顯示根據本專利案揭示之發明原理用於示波器之輸入電路之一實施例之若干可能的實施細節。
第4圖顯示根據本專利案揭示之發明原理用於示波器前端之一新穎架構。
第5圖顯示先前技術可變增益放大器(VGA)。
第6圖顯示根據本專利案揭示之發明原理VGA電路之一實施例。
第7圖顯示根據本專利案揭示之發明原理用於具有可變衰減器前端之VGA之主放大器之一實施例。
第8圖顯示根據本專利案揭示之發明原理具有整合型濾波器控制之放大器之一實施例。
第9圖顯示根據本專利案揭示之發明原理之放大器之另一實施例。
第10圖顯示V鏡，又名低回動電流鏡之一般實施例。
第11圖顯示根據本專利案揭示之發明原理適合用於放大器之V鏡之一實施例。

Claims (2)

  1. 一種用於一儀表系統之輸入系統，該輸入系統包含：一輸入級，其接收欲被測量之一信號；及一可變增益放大器，其具有耦接至該輸入級之一輸出端之一輸入端；其中該可變增益放大器包含二個或多個增益級；及其中該等二個或多個增益級之各者對整個該輸入系統之響應設置一低通濾波器極點；其中該等二個或多個增益級之各者包含一固定增益放大器及一可變衰減器。
  2. 如申請專利範圍第1項之輸入系統，進一步包含一輸出級，其具有耦接至該可變增益放大器之一輸出端之一輸入端。
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Publication number Priority date Publication date Assignee Title
US7088179B2 (en) * 2003-09-15 2006-08-08 Analog Devices, Inc. Single-ended input, differential output low noise amplifier
EP2075910A1 (en) * 2007-12-28 2009-07-01 Varian B.V. Instrumentation amplification with input offset adjustment
US8289811B2 (en) * 2009-09-01 2012-10-16 The Johns Hopkins University System and method for determining location of submerged submersible vehicle
US7714658B1 (en) * 2008-11-24 2010-05-11 Linear Technology Corporation Method and system for variable-gain amplifier
US8456173B2 (en) * 2009-09-30 2013-06-04 Tektronix, Inc. Signal acquisition system having probe cable termination in a signal processing instrument
US8436624B2 (en) * 2009-09-30 2013-05-07 Tektronix, Inc. Signal acquisition system having reduced probe loading of a device under test
US8564308B2 (en) * 2009-09-30 2013-10-22 Tektronix, Inc. Signal acquisition system having reduced probe loading of a device under test
US8278940B2 (en) * 2009-09-30 2012-10-02 Tektronix, Inc. Signal acquisition system having a compensation digital filter
US8405455B2 (en) * 2010-09-27 2013-03-26 EADS North America, Inc. Amplifier and method for linearizing same
EP2490332A1 (en) * 2011-02-16 2012-08-22 Nxp B.V. A variable gain amplifier
RU2468503C1 (ru) * 2011-09-28 2012-11-27 Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Южно-Российский государственный университет экономики и сервиса" (ФГБОУ ВПО "ЮРГУЭС") Каскодный усилитель
CN102427359B (zh) * 2011-12-06 2014-03-26 四川和芯微电子股份有限公司 插值电路及插值系统
CN102684621B (zh) * 2012-05-22 2014-11-05 华为技术有限公司 可变增益放大器
TWI445971B (zh) * 2012-07-20 2014-07-21 Wistron Corp 信號量測系統
US10161977B2 (en) * 2014-06-12 2018-12-25 Taiwan Semiconductor Manufacturing Company, Ltd. Circuit and method for gain measurement
US9929694B2 (en) * 2014-09-30 2018-03-27 Skyworks Solutions, Inc. Schottky enhanced bias circuit
KR101953496B1 (ko) 2014-12-03 2019-02-28 텔레호낙티에볼라게트 엘엠 에릭슨(피유비엘) 감쇠기
IT201600110367A1 (it) * 2016-11-03 2018-05-03 St Microelectronics Srl Procedimento per il controllo di amplificatori, circuito e dispositivo corrispondenti
CN106646000A (zh) * 2016-12-19 2017-05-10 西安微电子技术研究所 一种测量模拟开关电荷注入量的装置及方法
CN106841976A (zh) * 2016-12-19 2017-06-13 西安微电子技术研究所 一种测试模拟开关通道转换无效输出时间的装置
US9866179B1 (en) * 2017-04-05 2018-01-09 SiTune Corporation Multipath linear low noise amplifier
US10284144B2 (en) * 2017-10-04 2019-05-07 Novatek Microelectronics Corp. Amplifier circuit of high response speed and related clamping method
JP2019146163A (ja) * 2018-02-05 2019-08-29 テクトロニクス・インコーポレイテッドＴｅｋｔｒｏｎｉｘ，Ｉｎｃ． ノイズ・フィルタ及びノイズ低減方法
WO2019222648A1 (en) * 2018-05-18 2019-11-21 Gentex Corporation Headset communication system
US11063564B2 (en) 2019-02-15 2021-07-13 Semiconductor Components Industries, Llc Bidirectional leakage compensation circuits for use in integrated circuits and method therefor
TWI716817B (zh) * 2019-02-19 2021-01-21 立積電子股份有限公司 其電晶體都是雙極性接面型電晶體的功率偵測器
WO2020259804A1 (en) * 2019-06-25 2020-12-30 Huawei Technologies Co., Ltd. Amplifier with a converting circuit with reduced intrinsic time constant
CN112468104A (zh) * 2019-09-09 2021-03-09 深圳市中兴微电子技术有限公司 一种运算放大器
CN111610365A (zh) * 2020-05-09 2020-09-01 深圳市火乐科技发展有限公司 频谱分析装置及频谱分析方法
US11979125B2 (en) 2022-03-09 2024-05-07 Analog Devices, Inc. Techniques to externally control amplifier gain

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TW406192B (en) * 1997-11-14 2000-09-21 Ibm High input impedance single ended, low supply voltage magnetoresistive preamplifier circuits
US6504393B1 (en) * 1997-07-15 2003-01-07 Applied Materials, Inc. Methods and apparatus for testing semiconductor and integrated circuit structures
TWI232942B (en) * 2003-10-03 2005-05-21 Rich Wave Technology Corp Analytical apparatus and method for power gain and loss in multi-stage RF amplifier

Family Cites Families (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3308392A (en) * 1965-02-04 1967-03-07 Esso Production Company Seismic amplifier having means for changing the amplification of the seismic signal by discrete steps proportional to a given power of two
US3436673A (en) * 1965-11-22 1969-04-01 Monsanto Co Converter circuit
FR2558997B1 (fr) * 1984-01-31 1989-02-03 Thomson Csf Amplificateur correcteur du temps de propagation de groupe de signaux electriques et chaine d'amplification a frequence intermediaire de faisceaux hertziens comportant un tel amplificateur
US5077541A (en) * 1990-08-14 1991-12-31 Analog Devices, Inc. Variable-gain amplifier controlled by an analog signal and having a large dynamic range
US6011431A (en) 1994-11-23 2000-01-04 Analog Devices, Inc. Automatically tracking multiple-pole active filter
US5572166A (en) 1995-06-07 1996-11-05 Analog Devices, Inc. Linear-in-decibel variable gain amplifier
US6437630B1 (en) * 1999-12-28 2002-08-20 Analog Devices, Inc. RMS-DC converter having gain stages with variable weighting coefficients
US7072427B2 (en) 2001-11-09 2006-07-04 Parkervision, Inc. Method and apparatus for reducing DC offsets in a communication system
JP2003234629A (ja) * 2002-02-12 2003-08-22 Hitachi Ltd 自動利得調整回路及びそれを用いた増幅器
US6753727B2 (en) * 2002-06-13 2004-06-22 Skyworks Solutions, Inc. Sequential DC offset correction for amplifier chain
US7088179B2 (en) * 2003-09-15 2006-08-08 Analog Devices, Inc. Single-ended input, differential output low noise amplifier
JP4750463B2 (ja) 2005-05-11 2011-08-17 ルネサスエレクトロニクス株式会社 高周波電力増幅器およびそれを用いた送信器および移動体通信端末
US7397295B2 (en) * 2006-02-02 2008-07-08 Lsi Corporation Active current cancellation for high performance video clamps
US7400203B2 (en) * 2006-08-03 2008-07-15 Broadcom Corporation Circuit with Q-enhancement cell having feedback loop

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6504393B1 (en) * 1997-07-15 2003-01-07 Applied Materials, Inc. Methods and apparatus for testing semiconductor and integrated circuit structures
TW406192B (en) * 1997-11-14 2000-09-21 Ibm High input impedance single ended, low supply voltage magnetoresistive preamplifier circuits
TWI232942B (en) * 2003-10-03 2005-05-21 Rich Wave Technology Corp Analytical apparatus and method for power gain and loss in multi-stage RF amplifier

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