WO2014139076A1 - 基于pmos晶体管的源级跟随器 - Google Patents

基于pmos晶体管的源级跟随器 Download PDF

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Publication number
WO2014139076A1
WO2014139076A1 PCT/CN2013/072409 CN2013072409W WO2014139076A1 WO 2014139076 A1 WO2014139076 A1 WO 2014139076A1 CN 2013072409 W CN2013072409 W CN 2013072409W WO 2014139076 A1 WO2014139076 A1 WO 2014139076A1
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source
pmos transistor
source follower
well
parasitic capacitance
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PCT/CN2013/072409
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English (en)
French (fr)
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刘松
杨飞琴
吴柯
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香港中国模拟技术有限公司
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Priority to PCT/CN2013/072409 priority Critical patent/WO2014139076A1/zh
Publication of WO2014139076A1 publication Critical patent/WO2014139076A1/zh

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    • HELECTRICITY
    • H03ELECTRONIC CIRCUITRY
    • H03FAMPLIFIERS
    • H03F3/00Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/50Amplifiers in which input is applied to, or output is derived from, an impedance common to input and output circuits of the amplifying element, e.g. cathode follower
    • H03F3/505Amplifiers in which input is applied to, or output is derived from, an impedance common to input and output circuits of the amplifying element, e.g. cathode follower with field-effect devices
    • HELECTRICITY
    • H03ELECTRONIC CIRCUITRY
    • H03KPULSE TECHNIQUE
    • H03K19/00Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits
    • H03K19/01Modifications for accelerating switching
    • H03K19/017Modifications for accelerating switching in field-effect transistor circuits

Definitions

  • the invention belongs to the field of source follower technology and relates to a source follower based on a PMOS transistor. Background technique
  • Source followers based on MOS devices are widely used in various functional circuits.
  • MOSFETs i.e., MOS transistors
  • a source follower can typically be used as a high-speed input buffer, which has a simple circuit, a source follower that provides high input impedance, low output impedance, and wide signal bandwidth; compared to a closed-loop-driven op amp, source There is no stability problem with the polar follower. Therefore, the source follower is ideal for buffers and driver circuits.
  • Figure 1 shows a schematic diagram of a conventional PMOS transistor, where) is a schematic diagram of its cross-section and (b) is an equivalent circuit diagram.
  • Figure 2 is a circuit diagram showing a conventional source follower formed based on the PMOS transistor shown in Figure 1.
  • a conventional PMOS transistor is selected to be formed on a P-type substrate or substrate U 1 , which includes an N well 1 13 , a source region 121 , a depletion region 122 , and a bulk terminal (hereinafter referred to as B).
  • 132 a source (hereinafter referred to as S) 133, a gate (Gate, hereinafter abbreviated as G) 134, a drain (Drain, hereinafter abbreviated as D) 135, and a gate dielectric layer 140.
  • the N well 1 13 may be of the N conductivity type, which may be formed by patterning the P type substrate 11 1 by N-type doping to form a PMOS transistor; in the N well 1 13 , patterning doping to form a source region 121 and the drain region 122, both of which may be formed by doping, may also be formed by step doping, and both of which are of the P conductivity type, the doping concentration is not limited, in the source region 121 and the drain region Between 122, a channel can be formed under the control of the gate bias; the source 133 can be formed by drawing a metal electrode from the source region 121, the drain electrode 135 can be formed by drawing a metal electrode from the drain region 122; and the body end 132 is formed from the N-well U3.
  • the gate dielectric layer 140 may be specifically, but not limited to, Si0 2 , which may be formed by patterning the surface of the substrate 11 of the silicon material, and the gate electrode 134 is formed between the source 133 and the drain 135. In order to avoid forward biasing of the above parasitic diode, the P-type substrate 111 biases the ground signal GND.
  • a PMOS transistor as shown in FIG. 1(a) is formed, and parasitic capacitances Csb , Cdb and Cb are usually formed in the PMOS transistor, wherein Csb is a source.
  • Region 121 and the diode formed between N-well 13 is 1 '(as shown in (a) 1) in junction capacitance, a diode between the drain region is formed ⁇ 113122 is C db and the N-well (FIG. 1)
  • the junction capacitance shown, Cb is the junction capacitance of the diode formed between the N well 1 13 and the P-type substrate 11 1 (as shown in Figure 1 (a)).
  • the existing source follower formed based on the PMOS transistor shown in FIG. 1 inevitably there are at least three parasitic capacitances of C sb , C db , and C b . Since the PMOS transistor has a characteristic that the gain varies with the voltage of the output signal, that is, there is voltage dependency, the existing PMOS transistor-based source follower is prone to large distortion when the input signal swing is large. Therefore, it is easy to linearly distort and has poor linearity.
  • the high frequency performance of the source follower of the PMOS transistor has an effect. Therefore, when the source follower of the existing PMOS transistor is applied at a high frequency or a high speed, dynamic distortion is likely to occur.
  • One of the objects of the present invention is to improve the linearity of the source follower.
  • the present invention provides a PMOS transistor-based source follower comprising a current source and a PMOS transistor serving as an input device, wherein a gate of the PMOS transistor is defined as the source An input terminal (V in ) of the follower, a source of the PMOS transistor is defined as an output terminal (V. ut ) of the source follower, and a drain of the PMOS transistor is connected to a ground signal (GND), high a level signal (V DD ) is connected from one end of the current source, and the other end of the current source outputs a current to the source;
  • the body end of the PMOS transistor is connected to the input terminal (V in ) such that the voltage (V sb ) between the source and the body terminal remains substantially constant in the case where the input signal changes.
  • the source follower, wherein the PMOS transistor comprises:
  • a first parasitic capacitance (C sb ) caused by a diode formed between the source region and the N well, and between the drain region and the N well a second parasitic capacitance (C db ) caused by the formed diode, a third parasitic capacitance (C b ) caused by a diode formed between the N well and the P-type substrate.
  • the first parasitic capacitance (C sb ) is equivalently placed between the source and the body end, and the second parasitic capacitance (C db ) and the third parasitic capacitance (C b ) are equivalent.
  • Ground is placed in parallel between the body end and the drain end.
  • the P-type bottom is grounded.
  • the technical effect of the present invention is that by connecting the body end of the N-well with the input terminal V in , on the one hand, the gain of the source follower can be affected by the receptor effect, the linearity is improved, and the linear distortion is greatly reduced; in one aspect, can be skillfully the source follower output of the parasitic capacitance of a significant reduction in the frequency of the input terminal V in the input signal is changed, the dynamic distortion, to solve the problem in case T high frequency input signal dynamic distortion . Therefore, the source follower of the present invention is well suited for high speed, large negative 3 ⁇ 4 applications.
  • FIG. 1 is a schematic diagram of a conventional PMOS transistor, in which (a) is a cross-sectional structure thereof, and (b) is an equivalent circuit diagram thereof.
  • FIG. 2 is a circuit diagram of a source follower formed based on the PMOS transistor shown in FIG. 1.
  • FIG. 3 is a circuit diagram of a source follower formed in accordance with an embodiment of the present invention based on a PMOS transistor. detailed description
  • FIG. 2 is a circuit diagram showing a source follower formed based on the PMOS transistor shown in FIG.
  • the PMOS transistor is used as an input device
  • the gate of the PMOS transistor is used as the input terminal V in
  • the input signal (for example, the signal outputted from the previous stage) is input from the gate
  • the source of the PMOS transistor is used as the output terminal V.
  • Ut drain bias ground signal GND, the body terminal is also biased to ground signal GND; and, the current source is placed between the power signal V DD and the source, which provides a constant bias current for the input device, high level
  • the power signal V DD is biased at the source after passing through the current source.
  • C db is placed between the drain D and the body terminal B
  • C sb is placed between the source S and the body terminal B
  • C b is also placed between the drain D and the body terminal B in parallel with 'Cdb.
  • the output signal of the source follower shown in Figure 2 can follow the input signal change, and its gain (? can be calculated by the following formula (1):
  • r 0 is the output impedance of the input device (here a PMOS transistor), which is in parallel with the current source;
  • C ⁇ is the transconductance of the PMOS transistor.
  • the gain Gain of the source follower is approximately equal to 1, that is, the output signal substantially follows the input signal.
  • the gain is similarly calculated by the formula (1).
  • the actual input device r It varies with the change of the voltage level of the output signal, so that its gain Gain also changes with the voltage of the output signal.
  • This characteristic is usually called voltage dependence. This voltage dependence causes the source follower to exhibit a nonlinear characteristic when the input signal swings at a high amplitude, that is, large distortion is likely to occur when the input signal swing is large.
  • the fundamental cause of linear distortion in the source follower is the one that causes voltage dependence.
  • body effect This is because / ⁇ varies with the bias voltage between the source and the substrate ( ⁇ ), that is, with V sb ; when the substrate is grounded, the source is the voltage of the output signal (approximately equal to the voltage of the input signal) ), V sb varies with the voltage of the input signal, and the gain Gain of ra and the source follower changes with the voltage of the input signal.
  • the body terminal B of the PMOS transistor is normally directly connected to its source S.
  • the voltage V sb between the source S and the body terminal B is substantially constant to zero, thus substantially eliminating the body effect, and the gain Gain of the w and source follower does not follow the input of the source follower (ie The voltage of the input signal of the gate) changes, and the voltage dependency is also eliminated.
  • the source follower shown in Figure 2 greatly reduces linear distortion and provides relatively better linearity.
  • the output terminal V. Ui is connected to the parasitic capacitances Cdb and C b (C sb is not present at the output due to the substrate connection); when the input signal frequency rises, part of the output current through the PM 0 S transistor is shunted to the capacitor channel at the output ( Negative capacitance or parasitic capacitance), since this dynamic current varies with the input signal frequency, which causes the output impedance ra of the input device to be voltage dependent. Therefore, the gain Gain of the source follower varies with the signal voltage. , causing dynamic distortion. The higher the frequency of the input signal, the larger the capacitance (including parasitic capacitance) at the output and the more severe the dynamic distortion.
  • FIG. 3 is a circuit diagram of a source follower formed in accordance with an embodiment of the present invention based on the PMOS transistor shown in FIG. 1.
  • the PMOS transistor of the embodiment shown in FIG. 1 is also selected as the input device, the power supply voltage V DD is connected to the current source, and the current source is placed at the source and the high level of the power supply voltage (V DD ). Between, it is used to provide a substantially constant bias current for the input device; the input signal of the source follower is input from the gate G of the PMOS transistor, and the gate G is defined as the input terminal V m of the gate follower; the signal is from the PMOS The source S of the transistor is output and the source S' is defined as the output V of the source follower.
  • the drain D PMOS transistor and a P-type substrate 111 is grounded bias signal GND.
  • the body and the input terminal B or V in the gate G is connected, for example, in FIG. 1, the end member 132 may be directly to the gate 134 'is connected.
  • the source follower of the embodiment of Figure 3 will have both of the following advantages.
  • the effect of the effect is better than that of the conventional source follower, and the linear distortion is greatly reduced.
  • the source of the embodiment shown in FIG. 3 follows but reduces the linear distortion caused by the bulk effect, and also eliminates the dynamic distortion caused by the parasitic capacitance of the PMOS transistor. Large negative application occasions.
  • the input terminal V in is the input signal for the output circuit of the preceding stage, for example, the front-stage circuit may be an operational amplifier.
  • the specific type of input signal is not limiting.
  • the source follower of the embodiment of Figure 3 is not only suitable for fabrication in an integrated circuit, but is also suitable for connection by a PMOS transistor separation device through a line connection.

Abstract

本发明提供一种基于PMOS晶体管的源极跟随器,属于源极跟随器技术领域。该源极跟随器包括电流源和用作输入器件的PMOS晶体管,其中,所述PMOS晶体管的体端与源极跟随器的输入端(Vin)连接,以至于使N阱NMOS晶体管的源极与体端之间的电压(Vsb)在输入信号变化的情况下基本保持恒定。该源极跟随器失真小、线性度好,尤其适合于在高速大负载场合应用。

Description

基于 PMOS晶体管的源级跟随器 技术领域
本发明属于源极跟随器技术领域, 涉及基于 PMOS晶体管的源极 跟随器。 背景技术
基于 MOS器件(即 MOSFET, 也即 MOS晶体管)的源极跟随器 被广泛应用于各种功能电路中。 例如, 源极跟随器通常可以用作高速 输入援沖, 它电路结枸简单, 源极跟随器可以提供高输入阻抗、 低输 出阻抗和宽信号带宽; 相比于基于闭环驱动的运算放大器, 源极跟随 器不存在稳定性问题。 因此, 源极跟随器非常适用于緩冲器和驱动电 路。
图 1 所示为传统 PMOS晶体管的示意图, 其中 ) 为其截面结 构示意图, (b ) 为其等效电路示意图。 图 2所示为基于图 1 所示的 PMOS晶体管所形成的传统源极跟随器的电路示意图。
如图 1 ( a )所示, 传统 PMOS晶体管选择在 P型衬底或基片 U 1 上形成, 其包括 N阱 1 13、 源区 121、 竭区 122、 体端 (Bulk, 以下简 称为 B ) 132、 源极(Source, 以下筒称为 S ) 133、 栅极(Gate, 以下 简称为 G ) 134、 漏极 (Drain, 以下简称为 D ) 135和栅介质层 140。 其中, N阱 1 13可以为 N导电类型, 其可以通过对 P型衬底 1 1 1构 图 N型掺杂形成, 用来形成 PMOS晶 管; 在 N阱 1 13 中, 构图掺 杂形成源区 121和漏区 122, 二者可以,同^掺杂形成, 也可以分步掺 杂形成, 并且二者同为 P导电类型, 其具 掺杂浓度不是限制性的, 在源区 121和漏区 122之间, 可以栅偏压的控制下可以形成沟道; 源 极 133可以从源区 121 引出金属电极形成, 漏极 135可以从漏区 122 引出金属电极形成; 体端 132从 N阱 U3中引出形成; 栅介质层 140 具体可以但不限于为 Si02, 其可以通过对硅材料的衬底 1 1 1的表面构 图氧化形成, 栅极 134形成在源极 133和¾极 135之间。 为避免上述 寄生二极管正向偏置, P型村底 111偏置接地信号 GND。
按照以上实施例形成如图 1 ( a )所示的 PMOS晶体管的同时, 该 PMOS晶体管中通常会形成寄生电容 Csb 、 Cdb和 Cb, 其中, Csb为源 区 121 与 N阱 1 13之间形成的二极管 '(如图 1 ( a ) 中所示) 的结电 容, Cdb为漏区 122与 N阱 1 13之间形成^二极管 (如图 1 ) 中所 示)的结电容, Cb为 N阱 1 13与 P型衬底 1 1 1之间形成的二极管(如 图 1 ( a ) 中所示) 的结电容。
现有的基于图 1所示的 PMOS晶体管形成的源极跟随器中, 不可 避免地至少存在 Csb 、 Cdb和 Cb三个寄生电容。 由于 PMOS晶体管存 在增益 会随输出信号的电压的变化而变化的特性, 即存在电压 依赖性, 因此, 现有的基于 PMOS晶体管的源极跟随器在输入信号摆 幅较大时容易发生较大失真, 从而容易线性失真, 线性度差。
并且, 由于 Csb 、 Cdb和 Cb三个寄生电容的存在, 其容易对基于
PMOS晶体管的源极跟随器的高频性能产生影响,因此,现有的 PMOS 晶体管的源极跟随器高频或高速应用时, 容易产生动态失真。
有鉴于此, 有必要提出一种新型的源 跟随器。 发明内容
本发明的目的之一在于, 提高源极跟随器的线性度。
本发明的又一目的在于, 减小源极跟哆器的输出信号的线性失真 和动态失真。
为实现以上目的或者其他目的, 本发明提供一种基于 PMOS晶体 管的源极跟随器,包括电流源和用作输入器件的 PMOS晶体管,其中, 所述 PMOS晶体管的栅极被定义为所述源极跟随器的输入端 (Vin ) , 所述 PMOS晶体管的源极被定义为所述源极跟随器的输出端(V。ut ) , 所述 PMOS晶体管的漏极连接接地信号(GND ), 高电平信号( VDD ) 从所述电流源的一端接入, 并且所述电流源的另一端输出电流至所述 源极;
其中, 所迷 PMOS晶体管的体端 与所述输入端( Vin )连接, 以至于使所述源极与所述体端之间的电压 ( Vsb )在输入信号变化的情 况下基本保持恒定。
按照本发明一实施例的源极跟随器, 其中, 所述 PMOS晶体管包 括:
P型衬底;
在所述 P型衬底中构图掺杂形成的 N阱; 从所述 N阱中引出的体端 (B ) ;
在所迷 N阱中构图掺杂形成的源区和漏区;
从所迷漏区中引出的源极 (S ) ;
从所述漏区中引出的漏极 (D ) ; 以及
栅极 ( G ) 。
在一实施例中, 所述 PMOS晶体管中, 存在所迷源区与所述 N阱 之间形成的二极管所导致的第一寄生电容(Csb ) 、 所述漏区与所述 N 阱之间形成的二极管所导致的第二寄生电容 (Cdb ) 、 所述 N 阱与所 述 P型衬底之间形成的二极管所导致的第三寄生电容 (Cb ) 。
其中, 所述第一寄生电容(Csb )等效地置于所述源极和所述体端 之间, 所述第二寄生电容(Cdb ) 、 第三寄生电容(Cb )等效地并联置 于所述体端和所述漏端之间。
具体地, 所述 P型村底接地。
本发明的技术效果是, 通过将 N阱的体端与输入端 Vin连接在一 起, 一方面可以使源极跟随器的增益不受体效应影响, 提高线性度并 且线性失真大大减小; 另一方面, 可以巧妙地使源极跟随器的输出端 的寄生电容显著减少, 在输入端 Vin的 入信号的频率发生变化时, 动态失真小,解决在高频输入信号的情 T 动态失真的问题。 因此, 本发明的源极跟随器非常适合于高速大负 ¾场合应用。 附图说明
从结合附图的以下详细说明中, 将会使本发明的上述和其他目的 及优点更加完整清楚,其中,相同或相似的要素采用相同的标号表示。
图 1是传统 PMOS晶体管的示意图, 其中 (a ) 为其截面结构示 意图, (b ) 为其等效电路示意图。
图 2是基于图 1所示的 PMOS晶体管所形成的一种源极跟随器的 电路示意图。
图 3是基于图 1所示的 PMOS晶体.管所形成的按照本发明一实施 例的源极跟随器的电路示意图。 具体实施方式
下面介绍的是本发明的多个可能实施例中的一些, 旨在提供对本 发明的基本了解, 并不旨在确认本发明的关键或决定性的要素或限定 所要保护的范围。 容易理解, 根据本发明的技术方案, 在不变更本发 明的实质精神下, 本领域的一般技术人员可以提出可相互替换的其他 实现方式。 因此, 以下具体实施方式以及附图仅是对本发明的技术方 案的示例性说明, 而不应当视为本发明的全部或者视为对本发明技术 方案的限定或限制。
将理解, 当据称将部件 "连接 "到另一个部件时, 它可以直接连接 到另一个部件或可以存在中间部件。相反, 当据称将部件 "直接连接" 到另一个部件时, 则表示不存在中间部件:
图 2所示为基于图 1所示的 PMOS晶体管所形成的一种源极跟随 器的电路示意图。 其中, PMOS晶体管用作输入器件, PMOS晶体管 的栅极用作输入端 Vin, 输入信号 (例如前一级输出的信号) 从栅极 输入; PMOS晶体管的源极用作输出端 V。ut;漏极偏置接地信号 GND , 体端也偏置接地信号 GND; 并且, 将电流源置于电源信号 VDD和源 极之间, 其为输入器件提供恒定的偏置电流, 高电平的电源信号 VDD 经过电流源后偏置在源极上。 因此, Cdb置于漏极 D和体端 B之间, Csb置于源极 S和体端 B之间, Cb也与 ' Cdb并联地置于漏极 D和体端 B之间。 图 2所示的源极跟随器的输出信号可以跟随输入信号变化, 其增益(? 可以通过以下公式 ( 1 ) 计算:
Gain = ― ("
ro +——
Gm
其中, r0是输入器件 (在此为 PMOS晶体管) 的输出阻抗, 其与 电流源并联; C ^是 PMOS 晶体管的跨导。 通常 r0 » l/G , 因此, 源 极跟随器的增益 Gain接近等于 1 ,也即,输出信号基本跟随输入信号。
传统的 PMOS 晶体管的源极跟随器中, 也是类似地以公式 ( 1 ) 来计算增益。 但是, 由于实际上输入器件的 r。是随输出信号的电压电 平的变化而有所变化的, 从而导致其增益 Gain 亦随输出信号的电压 的变化而变化, 这种特性通常称为电压依赖性。 这种电压依赖性会导 致输入信号在高幅度摆动时, 源极跟随器呈现非线性特性, 也即, 在 输入信号摆幅较大时容易发生较大失真。
源极跟随器产生线性失真的根本原因在于引起电压依赖性的一 个重要因素: 体效应。 这是由于, /Ό是随源极和衬底 (Β ) 之间的偏 压而变化, 也即随 Vsb变化; 当衬底接地时, 源极为输出信号的电压 (约等于输入信号的电压) , Vsb随输入信号的电压而变化, ra和源 极跟随器的增益 Gain均随输入信号的电压变化而变化。
因此, 在图 2所示实施例的源极跟随器中, 通常地, 将 PMOS晶 体管的体端 B与自身的源极 S直接连接在一起。 这样, 源极 S与体端 B之间的电压 Vsb基本恒定为零, 这样, 基本消除了体效应, w和源 极跟随器的增益 Gain 并不会随源极跟随器的输入端 (即栅极) 的输 入信号的电压变化而变化, 也消除了电压依赖性。 与传统的源极跟随 器相比较, 图 2所示的源极跟随器大大减小了线性失真, 可以提供相 对更好的线性度。
但是, 申请人发现, 在图 2实施例的源极跟随器中, 输出端 V。ui 连接寄生电容 Cdb和 Cb ( Csb因衬底连接^ ^路, 不呈现在输出端) ; 当输入信号频率上升时,通过 P M 0 S晶体管的部分输出电流会分流到 输出端的电容通道(负栽电容或寄生电容) , 由于这个动态电流是随 输入信号频率而变化, 这会导致输入器,件的输出阻抗 ra也具有电压依 赖性,因此,源极跟随器的增益 Gain随信号电压变化, 引起动态失真。 输入信号的频率越高, 输出端的电容(包括寄生电容) 越大, 动态失 真越严重。
图 3所示为基于图 1所示的 PMOS晶体管所形成的按照本发明一 实施例的源极跟随器的电路示意图。 在图 3所示实施例中, 同样选择 图 1所示实施例的 PMOS晶体管作为输入器件, 电源电压 VDD接入电 流源, 电流源置于源极和高电平的电源电压 (VDD ) 之间, 其用于为 输入器件提供基本恒定的偏置电流; 源 跟随器的输入信号从 PMOS 晶体管的栅极 G输入, 栅极 G被定义 ^极跟随器的输入端 Vm; 信 号从 PMOS晶体管的源极 S输出,源极 S'被定义为源极跟随器的输出 端 V。ut; 进一步, PMOS晶体管的漏极 D和 P型衬底 1 1 1偏置接地信 号 GND。 尤其地, 将体端 B与输入端 Vin或栅极 G连接, 例如, 在图 1 中, 可以将体端 132与栅极 134直接'连接。 这样, 图 3所示实施例 的源极跟随器将同时具有以下两方面的优点。
第一, 考虑了基于 PMOS晶体管的源极跟随器的体效应问题。 可 以注意到, 在图 3所示实施例中, 由于体端 B与输入端 Vin或栅极 G 连接, 体端 B等于栅极 G的电位, 因此 Vsb=Vsg; 又由于源极跟随器 中源极 S电压跟随输入栅极 G, 因此 Vsg将是一个常量, 它不会随输 入信号的电压的变化而改变, 也即, 不存在电压依赖性问题。 图 3所 示的源极跟随器的增益 Gain ( Gain的 可以类似地通过公式 ( 1 ) 计算, 其中, r0是输入器件的输出阻抗.; :Gm是 PMOS晶体管的跨导) 也不受体效应影响, 相比传统的源极跟随器, 其线性度好, 线性失真 大大减小。
第二,考虑了输出端的寄生电容对刼态失真的影响。可以注意到, 在图 3所示实施例中, 通过将体端 B与输入端 Vin或栅极 G连接, Cdb 和 Cb并联地置于体端 B与漏端 D之间, Cdb和 Cb不再出现在输出端 Vout; 并且对于 Csb来说, 虽然其置于源端 S和体端 B之间, 但是如 前所述, Vsb=Vsg, Vsb电压值也为一常量(不随输入信号的电压变化 而变化) , 从而寄生电容 Csb不会增加输出端 V。ut的电容总量。 这样, 与图 4所示源极跟随器结构相比, 其输出端的寄生电容显著减少, 在 输入端 Vin的输入信号的频率发生变化时, 不会出现以上图 4所示源 极跟随器的电压依赖性问题和动态失真 ^。
综上, 图 3所示实施例的源极跟随 但减少了由体效应引起的 线性失真,还消除了 PMOS晶体管的寄生黾容所导致的动态失真的问 具有良好的高^特性 非常适合在高速大负栽场合应用。 ' 一 、 需要理解的是, 输入端 Vin的输入信号可以为前一级电路的输出, 例如, 前一级电路可以为运算放大器。 输入信号的具体类型不是限制 性的。
还需要理解的是, 图 3所示实施例的源极跟随器不仅适于在集成 电路中制造形成, 也适于由 PMOS 晶体管分离器件通过线路连接形 成。
以上例子主要说明了本发明的基于 PMOS晶体管的源极跟随器。 尽管只对其中一些本发明的实施方式进;f了描述, 但是本领域普通技 术人员应当了解, 本发明可以在不偏离^" 旨与范围内以许多其他的 形式实施。 闳此, 所展示的例子与实施 '方式 '被视为示意性的而非限制 性的, 在不脱离如所附各权利要求所定义的本发明精神及范围的情况 下, 本发明可能涵盖各种的修改与替换。

Claims

权 利 要 求
1. 一种基于 PMOS 晶体管的源极跟随器, 包括电流源和用作输 入器件的 PMOS晶体管, 其中, 所述 PMOS晶体管的栅极被定义为所 述源极跟随器的输入端(Vin) , 所述 PMOS晶体管的源极被定义为所 述源极跟随器的输出端 (V。ut) , 所迷 PMOS晶体管的漏极连接接地 信号 (GND) , 高电平信号 (VDD) 从所述电流源的一端接入, 并且 所述电流源的另一端输出电流至所述源极; 'ί
其特征在于, 所述 PMOS晶体管的体 ¾ (Β)与所述输入端( Vin) 连接, 以至于使所述源极与所述体端之间的电压(Vsb)在输入信号变 化的情况下基本保持恒定。
2. 如权利要求 1 所述的源极跟随器, 其特征在于, 所迷 PMOS 晶体管包括:
P型衬底;
在所述 P型衬底中构图掺杂形成的 N阱;
从所述 N阱中引出的体端 (B) ;
在所述 N阱中构图掺杂形成的源区和漏区;
从所迷漏区中引出的源极 (S),
从所述漏区中引出的漏极 (D), ; 以及
栅极 ( G ) 。
3. 如权利要求 1 所述的源极跟随器, 其特征在于, 所迷 PMOS 晶体管中,存在所述源区与所迷 N阱之间形成的二极管所导致的第一 寄生电容 (Csb) 、 所迷漏区与所述 N 阱之间形成的二极管所导致的 第二寄生电容 (Cdb) 、 所述 N阱与所迷 P型村底之间形成的二极管 所导致的第三寄生电容 (Cb) 。
4. 如权利要求 3所迷的源极跟随器, 其特征在于, 所述第一寄生 电容(Csb)等效地置于所述源极和所述体端之间, 所述第二寄生电容 ( Cdb) 、 第三寄生电容(Cb)等效地并,联置于所述体端和所述漏端之 间。
5. 如权利要求 2所述的源极跟随器, 其特征在于, 所述 P型衬底 接地。
PCT/CN2013/072409 2013-03-11 2013-03-11 基于pmos晶体管的源级跟随器 WO2014139076A1 (zh)

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JPH05191170A (ja) * 1992-01-13 1993-07-30 Nippon Telegr & Teleph Corp <Ntt> ソースフォロワ回路
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CN101647194A (zh) * 2007-03-29 2010-02-10 Nxp股份有限公司 一种改进的放大器
CN102084489A (zh) * 2008-07-02 2011-06-01 美国亚德诺半导体公司 动态驱动的深n阱电路
CN102110697A (zh) * 2009-12-03 2011-06-29 索尼公司 成像元件和相机系统
CN103199848A (zh) * 2013-03-11 2013-07-10 香港中国模拟技术有限公司 基于pmos晶体管的源极跟随器
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05191170A (ja) * 1992-01-13 1993-07-30 Nippon Telegr & Teleph Corp <Ntt> ソースフォロワ回路
CN101218683A (zh) * 2005-07-11 2008-07-09 派瑞格恩半导体有限公司 用累积电荷吸收器改进mosfet的线性的方法和设备
CN101647194A (zh) * 2007-03-29 2010-02-10 Nxp股份有限公司 一种改进的放大器
CN102084489A (zh) * 2008-07-02 2011-06-01 美国亚德诺半导体公司 动态驱动的深n阱电路
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