CN104883171A - Radio-frequency switch circuit with high isolation and low substrate leakage - Google Patents

Abstract

Translated fromChinese

本发明公开了一种高隔离度、低衬底泄露的射频开关电路，将传统的单刀多掷开关电路，多掷分组，每组并联不超过4掷，每掷由一个串联MOSFET管和一个并联MOSFET管组成，每组电路再串联一个MOSFET管，然后相互并联到主通路；每个MOSFET管的衬底都串联一个电容，电容的另一端接地；电路中栅极控制电压接在每个MOS管的栅极，衬底控制电压接在衬底与电容间的节点上。本发明结构较为简单、功耗小、电路集成度高。

The invention discloses a radio frequency switch circuit with high isolation and low substrate leakage. The traditional single-pole multi-throw switch circuit is grouped with multiple throws, and each group is connected in parallel with no more than 4 throws. Each throw is composed of a series MOSFET and a parallel MOSFET. Composed of MOSFET tubes, each group of circuits is connected in series with a MOSFET tube, and then connected in parallel to the main channel; the substrate of each MOSFET tube is connected in series with a capacitor, and the other end of the capacitor is grounded; the gate control voltage in the circuit is connected to each MOS tube The gate of the substrate control voltage is connected to the node between the substrate and the capacitor. The invention has relatively simple structure, low power consumption and high circuit integration degree.

Description

Translated fromChinese

一种高隔离度、低衬底泄露的射频开关电路A RF switch circuit with high isolation and low substrate leakage

技术领域technical field

本发明涉及射频开关电路，具体涉及一种高线性度、高隔离度适用于单刀十掷以上的射频开关电路。The invention relates to a radio frequency switch circuit, in particular to a radio frequency switch circuit with high linearity and high isolation suitable for single-pole ten-throw.

背景技术Background technique

在无线通信系统的收发机中，高性能的开关用于发射通路和接收通路信号的选择，开关的插入损耗、线性度、隔离度等性能直接制约着整个系统的输出功率、噪声系数等性能。尤其在如今的3G、4G广泛应用于移动电话的通信和导航中，收发机需要进行多个频段多种模式的选择，因此高性能的单刀多掷开关不可缺少。现今以硅为衬底的CMOS工艺仍是射频开关的主流工艺，该工艺以其超低的成本，优异的射频性能（低插入损耗、高隔离度和高线性度）被广泛应用于无线通信系统中。In the transceiver of the wireless communication system, the high-performance switch is used to select the signal of the transmission path and the reception path. The insertion loss, linearity, and isolation of the switch directly restrict the output power, noise figure, and other performance of the entire system. Especially in today's 3G and 4G widely used in the communication and navigation of mobile phones, the transceiver needs to select multiple frequency bands and multiple modes, so high-performance single-pole multi-throw switches are indispensable. Today, the silicon-based CMOS process is still the mainstream process for RF switches. This process is widely used in wireless communication systems due to its ultra-low cost and excellent RF performance (low insertion loss, high isolation and high linearity). middle.

传统的射频开关电路都是由一条与天线相连的主路引出几条相同的支路设计而成的。每条支路上通常都是串联一个MOSFET管和并联一个MOSFET管，通过控制MOSFET管的开（ON）和关（OFF）来实现电路的功能。在理想状态下，射频信号通过打开的MOSFET管，对于关闭的MOSFET管，射频信号完全反射回来，但由于MOSFET管高频条件下的一些寄生效应，实际中信号会发生一些损耗和泄漏（主要是衬底泄漏），当输入大信号时，这种效应会更加明显，而且大摆幅的电压通过MOSFET管时，输出端会产生高次谐波，会导致开关总体线性度降低，这些现象对我们在实际设计电路时将造成很大的困难。尤其是设计单刀十掷以上的射频开关，电路不仅存在信号衬底泄漏的问题，每条支路间的信号隔离也成为主要解决问题之一。Traditional radio frequency switch circuits are designed by leading several identical branch circuits from a main circuit connected to the antenna. Each branch usually connects a MOSFET tube in series and a MOSFET tube in parallel, and realizes the function of the circuit by controlling the opening (ON) and closing (OFF) of the MOSFET tube. In an ideal state, the RF signal passes through the turned-on MOSFET. For the turned-off MOSFET, the RF signal is completely reflected back. However, due to some parasitic effects under the high-frequency conditions of the MOSFET, some loss and leakage of the signal will occur in practice (mainly Substrate leakage), when a large signal is input, this effect will be more obvious, and when the large swing voltage passes through the MOSFET tube, the output terminal will generate high-order harmonics, which will cause the overall linearity of the switch to decrease. These phenomena are important to us It will cause great difficulty when actually designing the circuit. Especially in the design of RF switches with more than single pole ten throw, the circuit not only has the problem of signal substrate leakage, but also the signal isolation between each branch circuit has become one of the main problems to be solved.

对于上述问题，传统的方法是通过改变MOSFET管的栅长栅宽以及MOSFET管堆叠的个数来折衷优化电路的最佳性能，但是并不能从根本上解决这些问题，致使射频开关存在一定的局限性。For the above problems, the traditional method is to compromise the optimal performance of the circuit by changing the gate length and width of the MOSFET tube and the number of stacked MOSFET tubes, but it cannot fundamentally solve these problems, resulting in certain limitations in the RF switch sex.

发明内容Contents of the invention

 本发明针对现有技术的不足，提出了一种高隔离度、低衬底泄露的射频开关电路。Aiming at the deficiencies of the prior art, the present invention proposes a radio frequency switch circuit with high isolation and low substrate leakage.

本发明一种高隔离度、低衬底泄露的射频开关电路，将传统的单刀多掷开关电路，多掷分组，每组并联不超过4掷，每掷由一个串联MOSFET管和一个并联MOSFET管组成，每组电路再串联一个MOSFET管，然后相互并联到主通路；每个MOSFET管的衬底都串联一个电容，电容的另一端接地；电路中栅极控制电压接在每个MOS管的栅极，衬底控制电压接在衬底与电容间的节点上。The present invention is a radio frequency switch circuit with high isolation and low substrate leakage. The traditional single-pole multi-throw switch circuit is grouped with multiple throws, and each group is connected in parallel with no more than 4 throws. Each throw consists of a series MOSFET tube and a parallel MOSFET tube. Each group of circuits is connected in series with a MOSFET tube, and then connected in parallel to the main channel; the substrate of each MOSFET tube is connected in series with a capacitor, and the other end of the capacitor is grounded; the gate control voltage in the circuit is connected to the gate of each MOS tube pole, the substrate control voltage is connected to the node between the substrate and the capacitor.

所述的电容为CMOS工艺上的电容，属于fF的数量级。The capacitance mentioned above is a capacitance on a CMOS process, which belongs to the order of fF.

    有益效果：本发明提供了一种射频开关电路模型，用MOSFET管分别将几组射频接收支路隔离开来，将起隔离作用的MOSFET管偏置在三极管区，MOSFET管等效为一组并联的电阻电容网络，调整它的栅宽与栅长比，使电阻电容网络中的电阻变的很小，电容增大，由于每组接收支路间存在这么一个电容，所以对于单刀十掷以上的射频开关，每条支路的隔离度会提升很多，而这个电阻电容网络中的电阻很小，所以对于所有射频支路来说，它的插入损耗也很小,时延也较短。另外，由于MOS管的栅极、漏极、源极和衬底之间都存在寄生电容，尤其是信号频率上了1GHz后，这些寄生电容的值会变的很大，一般都在100fP左右,本发明通过在所有MOS管的衬底上串联一小电容，来减小寄生电容的影响，控制好小电容的容值可使MOS管到地的寄生电容变的很小，有用信号将不容易从衬底泄漏出来，而信号的高次谐波可以从衬底和小电容流到地上，电路的线性度会有很大的提高，另外，该电路结构较为简单、功耗小、电路集成度高。Beneficial effects: the present invention provides a radio frequency switch circuit model, using MOSFET tubes to isolate several groups of radio frequency receiving branches, biasing the isolated MOSFET tubes in the triode region, and the MOSFET tubes are equivalent to a group of parallel circuits Resistor-capacitor network, adjust its grid width to gate length ratio, so that the resistance in the resistor-capacitor network becomes small and the capacitance increases. Since there is such a capacitor between each group of receiving branches, it is necessary for single-pole ten-throw For RF switches, the isolation of each branch will be greatly improved, and the resistance in this resistor-capacitor network is very small, so for all RF branches, its insertion loss is also small and the delay is short. In addition, because there are parasitic capacitances between the gate, drain, source and substrate of the MOS transistor, especially after the signal frequency increases to 1GHz, the value of these parasitic capacitances will become very large, generally around 100fP, The present invention reduces the influence of parasitic capacitance by connecting a small capacitor in series on the substrates of all MOS transistors. Controlling the capacitance of the small capacitor can make the parasitic capacitance from the MOS transistor to the ground very small, and the useful signal will not be easy It leaks from the substrate, and the high-order harmonics of the signal can flow from the substrate and small capacitors to the ground, and the linearity of the circuit will be greatly improved. In addition, the circuit structure is relatively simple, the power consumption is small, and the circuit integration degree high.

附图说明Description of drawings

图1为MOS管衬底串联电容的模型图；Figure 1 is a model diagram of the MOS tube substrate series capacitance;

图2为MOS管衬底串联电容的等效电路图；Fig. 2 is the equivalent circuit diagram of the MOS transistor substrate series capacitance;

图3为本发明的结构示意图；Fig. 3 is a structural representation of the present invention;

图4为传统单刀十二掷射频开关电路的结构示意图；Fig. 4 is a schematic structural diagram of a traditional single-pole twelve-throw radio frequency switch circuit;

    图5为本发明的一种单刀十二掷射频开关电路的结构示意图。Figure 5 is a schematic structural diagram of a single-pole twelve-throw radio frequency switch circuit of the present invention.

具体实施方式Detailed ways

如图1、图2、图3、图4所示，一种高隔离度、低衬底泄露的射频开关电路将传统的单刀多掷开关电路，多掷分组，每组并联不超过4掷，每掷由一个串联MOSFET管和一个并联MOSFET管组成，每组电路再串联一个MOSFET管，然后相互并联到主通路；每个MOSFET管的衬底都串联一个电容，电容的另一端接地；电路中栅极控制电压接在每个MOS管的栅极，衬底控制电压接在衬底与电容间的节点上；所述的电容为CMOS工艺上的电容，属于fF的数量级。As shown in Figure 1, Figure 2, Figure 3, and Figure 4, a high-isolation, low-substrate-leakage RF switch circuit divides the traditional single-pole multiple-throw switch circuit into groups of multiple throws, and each group is connected in parallel with no more than 4 throws. Each throw consists of a series MOSFET and a parallel MOSFET, and each group of circuits is connected in series with a MOSFET, and then connected in parallel to the main path; each MOSFET substrate is connected in series with a capacitor, and the other end of the capacitor is grounded; in the circuit The gate control voltage is connected to the gate of each MOS transistor, and the substrate control voltage is connected to the node between the substrate and the capacitor; the capacitor is a capacitor in a CMOS process, and belongs to the order of fF.

图5为基于本发明的单刀十二掷射频开关的电路结构示意图，开关的总路与天线（ANT）相连，开关的十二个接收支路被分成三组，第一组有四条接收支路，这四条支路通过一个串联的MOSFET管（Stack I）与ANT相连，每条支路都串联一个MOS Stack和并联一个MOS Stack，Stack I、Stack A-D和Stack 1-4都是由MOSFET管堆叠而成的，每个MOSFET管的衬底都串联一个小电容，小电容另一端接地。第二组和第三组与第一组电路结构相同，由四条并联的接收支路与一个MOSFET管（Stack II、Stack III）串联而成，每条接收支路都串联一个MOS Stack和并联一个MOS Stack，Stack II-III、Stack E-L和Stack 5-12都是由MOSFET管堆叠而成的，同样的，每个MOSFET管的衬底都串联一个小电容，小电容另一端接地。每个MOSFET的栅极都接一个电压源，每个MOSFET的衬底与小电容间的节点也同样接一个电压源，当RF1支路上的Stack I和Stack 1管栅极电压为高电平，衬底电压为低电平，其它MOSFET管的栅极和衬底都为低电平，此时，Stack I和Stack 1管打开，其他MOSFET管都闭合，RF1支路为射频信号的收发通路，RF2～RF12以相同的原理工作。电路中的Stack I、Stack II和Stack III用于几组电路信号的隔离，改变对应MOS管的栅宽栅长之比，使两个堆叠管表现为很大电容特性，很小的电阻特性。与衬底相连的小电容为CMOS工艺上的电容，用于抵消寄生电容，减小信号的衬底泄漏，一般取到fF的数量级，可以很好的提高射频开关的线性度和隔离度。本发明的一种单刀十二掷射频开关电路结构对称、效果改善明显，不仅大大提高了每条支路间的隔离度，还改善了开关整体的线性度。Figure 5 is a schematic diagram of the circuit structure of the single-pole twelve-throw radio frequency switch based on the present invention, the main circuit of the switch is connected to the antenna (ANT), and the twelve receiving branches of the switch are divided into three groups, and the first group has four receiving branches , these four branches are connected to ANT through a series MOSFET tube (Stack I), each branch is connected in series with a MOS Stack and in parallel with a MOS Stack, Stack I, Stack A-D and Stack 1-4 are all stacked by MOSFET tubes The substrate of each MOSFET tube is connected in series with a small capacitor, and the other end of the small capacitor is grounded. The second and third groups have the same circuit structure as the first group, consisting of four parallel receiving branches connected in series with a MOSFET tube (Stack II, Stack III), and each receiving branch is connected in series with a MOS Stack and in parallel with a MOS Stack, Stack II-III, Stack E-L and Stack 5-12 are all stacked by MOSFET tubes. Similarly, the substrate of each MOSFET tube is connected in series with a small capacitor, and the other end of the small capacitor is grounded. The gate of each MOSFET is connected to a voltage source, and the node between the substrate and the small capacitor of each MOSFET is also connected to a voltage source. When the gate voltage of Stack I and Stack 1 on the RF1 branch is high, The substrate voltage is at low level, and the gates and substrates of other MOSFETs are at low level. At this time, Stack I and Stack 1 are turned on, and other MOSFETs are closed. The RF1 branch is the transceiver channel of radio frequency signals. RF2~RF12 work on the same principle. Stack I, Stack II and Stack III in the circuit are used to isolate several groups of circuit signals, and change the ratio of gate width to gate length of the corresponding MOS transistors, so that the two stacked transistors exhibit large capacitance characteristics and small resistance characteristics. The small capacitance connected to the substrate is the capacitance on the CMOS process, which is used to offset the parasitic capacitance and reduce the substrate leakage of the signal. Generally, it is on the order of fF, which can improve the linearity and isolation of the RF switch. The structure of the single-pole twelve-throw radio frequency switch circuit of the present invention is symmetrical, and the effect is significantly improved, which not only greatly improves the isolation between each branch circuit, but also improves the overall linearity of the switch.

以上实施方式仅用于说明本发明，这些描述都是示例，并不是对本发明应用范围的限制，本领域技术人员可以根据本发明的原理和电路模型对本发明做出各种变型和修改，这些变型和修改也在本申请的范围内。The above embodiments are only used to illustrate the present invention, and these descriptions are all examples, and are not intended to limit the scope of application of the present invention. Those skilled in the art can make various variations and modifications to the present invention according to the principles and circuit models of the present invention. and modifications are also within the scope of this application.

Claims (2)

Translated fromChinese

1. 一种高隔离度、低衬底泄露的射频开关电路，其特征在于：将传统的单刀多掷开关电路，多掷分组，每组并联不超过4掷，每掷由一个串联MOSFET管和一个并联MOSFET管组成，每组电路再串联一个MOSFET管，然后相互并联到主通路；每个MOSFET管的衬底都串联一个电容，电容的另一端接地；电路中栅极控制电压接在每个MOS管的栅极，衬底控制电压接在衬底与电容间的节点上。1. A radio frequency switch circuit with high isolation and low substrate leakage, characterized in that: the traditional single-pole multi-throw switch circuit is grouped with multiple throws, and each group is connected in parallel with no more than 4 throws, and each throw is composed of a series MOSFET tube and Each group of circuits is composed of a parallel MOSFET tube, and each group of circuits is connected in series with a MOSFET tube, and then connected in parallel to the main channel; the substrate of each MOSFET tube is connected in series with a capacitor, and the other end of the capacitor is grounded; the gate control voltage in the circuit is connected to each The gate of the MOS transistor and the substrate control voltage are connected to the node between the substrate and the capacitor.2.根据权利要求1所述的一种高隔离度、低衬底泄露的射频开关电路，其特征在于：所述的电容为CMOS工艺上的电容，属于fF的数量级。2. A radio frequency switch circuit with high isolation and low substrate leakage according to claim 1, characterized in that: said capacitance is a capacitance on CMOS technology, which belongs to the order of fF.