Radio frequency switch unit, radio frequency switch network and circuit structure
By disconnecting the target port and the source and drain voltage connection in the RF switching unit, ensuring that the transistor is in the off state, the problems of decreasing output power and increasing chip area in the RF switching network are solved, and the RF switching performance and output power are improved.
Patent Information
- Application Number
- CN202323468410.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-19
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2033-12-19
AI Technical Summary
Existing RF switches cause actual output power to fall when forming a network, affecting switching performance, and the multi-stage MOS tube cascade structure leads to an increase in the chip layout area.
A radio frequency switching unit is designed in which the gate and body of the switching transistor are connected to the corresponding voltage by resistor, the source/drain is connected to the source/drain of the adjacent transistor, and is disconnected from the source/drain voltage at the target port, A cross node is formed to reduce bias resistance and ensure that the transistor is in the off state.
Improves the performance of RF switches in the network, reduces the chip layout area, and connects the target port to the source and drain voltage to ensure stable transistor shutdown and enhances output power.
Smart Images
Figure CN222147591U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of radio frequency technology, and in particular to a radio frequency switch unit and a radio frequency switch network. Background Art
[0002] Existing RF switches mostly use a multi-stage MOS tube cascade structure, please refer to Figure 1 , is a schematic diagram of the structure of an existing RF switch. The RF switch includes a plurality of cascaded NMOS transistors, the gate of which is connected to the gate resistor R G Connect to gate voltage V G , the source and drain of the transistor are connected through the resistor R D Connect to source-drain voltage V D , the body passes through the resistor R B Connect to the body voltage (eg Figure 1 middle ground).
[0003] By multiple Figure 1 The RF switches shown can form a switch network, but this often results in a decrease in actual output power and affects switch performance. Utility Model Content
[0004] The utility model provides a radio frequency switch unit, a radio frequency switch network and a circuit structure, which can improve the performance of the radio frequency switch unit in an access circuit network and reduce the chip layout area of the radio frequency switch circuit.
[0005] The utility model proposes a radio frequency switch unit, comprising: a switch path composed of a plurality of cascaded switch transistors, the gates of the switch transistors are electrically connected to a gate voltage through a gate resistor, the body electrodes are electrically connected to a body voltage through a body resistor, the source / drain of the switch transistor and the source / drain of an adjacent switch transistor are connected in sequence; a source / drain on one side of at least one switch transistor located at an end of the switch path is connected to the source / drain of an adjacent switch transistor, and the source / drain of the other switch transistors is electrically connected to a source-drain voltage through a bias resistor; the source / drain on the other side, as a target port of the switch path, is disconnected from the source-drain voltage and is used to be connected to a line cross node of a circuit network.
[0006] Optionally, the voltage at the cross node is affected by another circuit branch other than the radio frequency switch unit and connected to the cross node.
[0007] The present application also provides a radio frequency switch network, comprising: at least three radio frequency switch units as described above; the target ports of the switch paths of the respective radio frequency switch units are interconnected to form a cross node of the radio frequency switch network.
[0008] Optionally, the other end of the switch path of the radio frequency switch unit other than the cross node serves as a signal input end or a signal output end.
[0009] Optionally, a DC blocking capacitor is connected in series to both the signal input terminal and the signal output terminal of the radio frequency switch network.
[0010] Optionally, the switch network includes n radio frequency switch units, and when the radio frequency switch network operates normally, at least two of the radio frequency switch units are in different working states, and n≥3.
[0011] Optionally, among the n RF switch units, at least one RF switch unit serves as an input signal path, and the remaining RF switch units serve as switchable output signal paths; when one of the input signal paths is connected to any one of the RF switch units serving as the output signal path, and the other RF switch units are closed, the output power of the switch network is: Pout = (N-1)*[2*(Vdd+Vth)] 2 / Zo+[2*(Vth)] 2 / Zo, where Vdd is the source-drain voltage, Vth is the threshold voltage of the switching transistor, N is the number of switching transistors cascaded in the RF switch unit, and Zo is the characteristic impedance of the RF working environment in which the RF switch unit is located, which is generally 50 ohms.
[0012] The present application also provides a circuit structure, comprising: a radio frequency switch unit as described in any of the above items, and at least one circuit branch; one end of the circuit branch is connected to a target port of the radio frequency switch unit to form a cross node; the voltage at the cross node is affected by the circuit branch.
[0013] Optionally, the circuit branch has an equivalent DC path connected from the cross node to another voltage source.
[0014] Optionally, when the circuit structure is in a working state, the circuit branch and the radio frequency switch unit have different voltage requirements at the cross node.
[0015] The source / drain of the switch transistor at one side of the end of the radio frequency switch unit provided by the utility model, which is used to connect to other circuits, is disconnected from the source-drain voltage, and is used to be connected to the circuit network, as the target port of the switch path, and is used to be connected to the line crossing node of the circuit network. Since the source / drain is disconnected from the source-drain voltage, the voltage at the line crossing node will not be affected by the bias voltage of the radio frequency switch unit. When the radio frequency switch unit is in the off state, the source-drain voltage is at a suitable bias voltage Vdd, ensuring that other switch transistors in the radio frequency switch unit are in the off state, thereby improving the performance of the radio frequency switch transistor in the switch network.
[0016] Furthermore, since the connection between the target port and the source-drain voltage is disconnected, the stable off state of the radio frequency switch unit is achieved by reducing the bias resistance, and there is no need to add additional isolation devices, which can reduce the chip area. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.
[0018] Figure 1 It is a structural schematic diagram of a radio frequency switch unit;
[0019] Figure 2 It is a structural schematic diagram of a radio frequency switch network;
[0020] Figure 3 It is a structural schematic diagram of a radio frequency switch network;
[0021] Figure 4 This is a schematic diagram of the structure of a radio frequency switch unit according to an embodiment of the present application;
[0022] Figure 5 This is a schematic diagram of the structure of a radio frequency switch network according to an embodiment of the present application;
[0023] Figure 6 A schematic diagram of the working state of a radio frequency switch network according to an embodiment of the present application;
[0024] Figure 7 FIG. 1 is a schematic diagram of a circuit structure according to an embodiment of the present application. DETAILED DESCRIPTION
[0025] The technical solutions in the embodiments of the present application are clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application. In the absence of conflict, the following embodiments and their technical features can be combined with each other.
[0026] Please refer to Figure 2 , in one implementation, using Figure 1 The radio frequency switch network composed of the radio frequency switch units.
[0027] When the RF switch units 10 and 12 are in the "ON" state, and the RF switch unit 11 is "OFF", the RF signal flow is as shown in the figure. The RF switch network usually connects a DC blocking capacitor C in series at the signal input and output ends. BLK , but each RF switch unit is usually directly connected to the network crosspoint VM.
[0028] According to the bias conditions of the switching state of the RF switch unit, Vds,on=0, and Vds,off=Vdd, then Figure 2 In this state, the V D,Off = Vdd, that is, the voltage at the S terminal of the RF switch unit 11 is Vdd; and the V D,on =0, the voltage at the S terminal of the RF switch unit 12 is 0; and similarly, the voltage at the D terminal of the RF switch unit 10 is V D,on =0; the three RF switch units are connected with a cross point VM, at which the voltage at VM is affected by the D end of the RF switch unit 10 and the S ends of the RF switch units 11 and 12. Since the states of the RF switch unit 11 and the RF switch unit 12 are different, there is a conflict in the voltage requirements at VM, and they have different bias voltage requirements, which will cause the S end voltage of the RF switch unit 11 to be affected by the S end voltage of the RF switch unit 12 and be pulled down, so that the off state of all the switch transistors in the RF switch unit 11 is affected, and the overall output power is greatly reduced.
[0029] For example, each RF switch unit has N switch transistors. Figure 2 In the case shown, Pout = N*[2*(Vth)] 2 / Zo, Zo is the characteristic impedance of the RF working environment where the RF switch unit is located, which is generally 50 ohms.
[0030] A single RF switch unit (such as Figure 1 ) output power, Pout = N*[2*(Vdd+Vth)] 2 / Zo. From this, we can see Figure 2 In this case, the output power of the composed RF switch network is much lower than the output power of a single RF switch unit, and the output power is greatly attenuated.
[0031] Please refer to Figure 3 , which is a structural diagram of another RF switch network.
[0032] In order to avoid voltage conflicts at VM, capacitors such as C1 and C2 can be connected in series at the connection of each RF switch unit of VM to isolate the bias voltage at each end of the connection of each RF switch unit to avoid conflicts and make the switch states of each switch branch independent of each other. However, due to the large size of capacitors, more capacitors need to be added for more complex RF switch networks, which will increase the chip area and cost.
[0033] In order to solve the above problems, the present application proposes a new structure of a radio frequency switch unit.
[0034] Please refer to Figure 4 , is a schematic structural diagram of a radio frequency switch unit according to an embodiment.
[0035] In this embodiment, the RF switch unit 100 includes: a switch path composed of a plurality of cascaded switch transistors M, the gates of the switch transistors M are connected through a gate resistor R G Electrically connected to the gate voltage V G , the body electrode is connected through the integrated electrode resistor R B Electrically connected to a body voltage. In this embodiment, the body voltage is ground. In other embodiments, it can be other voltages.
[0036] The source and drain of the switch transistor M are connected to the source and drain of the adjacent switch transistor in sequence; the source and drain of at least one switch transistor M1 located at the end of the switch path is connected to the source and drain of the adjacent switch transistor, and is connected to the source and drain of the other switch transistors through a bias resistor R D Electrically connected to source-drain voltage V D The other side source-drain electrode S of the switch transistor M1 at the end of the switch path is used as the target port of the switch path and the source-drain voltage V D The circuits are disconnected and used to connect to the line crossing nodes of the circuit network.
[0037] In particular, it is especially applicable that the voltage at the cross node is affected by another circuit branch other than the RF switch unit 100 and connected to the cross node.
[0038] The present application also provides a radio frequency switch network, comprising at least two Figure 4 The RF switch unit 100 described in the embodiment: The target ports of the switch paths of each RF switch unit 100 are connected to each other to form a cross node of the RF switch network.
[0039] Please refer to Figure 5 , is a schematic diagram of the structure of a radio frequency switch network according to an embodiment of the present application.
[0040] The RF switch network includes at least three Figure 4The RF switch units 100a, 100b and 100c described in the embodiment; the target ports of the switch paths of each RF switch unit are connected to each other to form a cross node VM of the RF switch network. Each RF switch unit serves as a branch of the RF switch network.
[0041] The other end of the switch path of the RF switch unit other than the cross node serves as a signal input end or a signal output end. Specifically, the RF switch unit 100a serves as a signal input branch, and the drain D of the switch transistor M1 at one end of the switch path serves as a signal output end, connected to the cross node VM, disconnected from the source-drain voltage VD, and the source S of the switch transistor at the other end of the switch path serves as a signal input end; while the RF switch units 100b and 100c serve as signal output branches, and the source S of the switch transistor M1 at one end of the switch path serves as a signal input end, connected to the cross node VM, and disconnected from the source-drain voltage VD, and the drain D of the transistor at the other end is connected to the source-drain voltage VD, serving as a signal output end.
[0042] In this embodiment, the signal input end (the source S of the switching transistor on the input end side of the RF switch unit 100a) and the signal output end (the drain D of the switching transistor on the output end side of the RF switch units 100b and 100c) of the entire RF switch network are both connected in series with a DC blocking capacitor C BLK , to improve the isolation performance of the entire RF switch network.
[0043] Please refer to Figure 6 ,for Figure 5 A schematic diagram of a working state of the radio frequency switch network.
[0044] The RF switch units 100a and 100c are turned on, which is in the "ON" state, while the RF switch network 100b is turned off, which is in the "OFF" state, and the RF signal is output through the RF switch network 100a and the RF switch unit 100c.
[0045] In order to meet the above working conditions, the RF switch network 100a and the RF switch network 100c meet the bias condition Vds,on=0; the source-drain voltage VD of the RF switch network 100a and the RF switch network 100c is set to V D =0.
[0046] The RF switch network 100b needs to satisfy the bias condition Vds,off=Vdd, and the source-drain voltage V D Set to Vdd.
[0047] Since the source voltage Vs of the switch transistor M1 in the RF switch unit 100 a is VD=0, and the drain voltage Vd of the switch transistor M1 in the RF switch unit 100 c is VD=0, the voltage at the cross node VM is zero.
[0048] The drain voltage Vd of the switch transistor M1 of the RF switch unit 100b is V D =Vdd, drain voltage Vs=0. Although the bias voltage of the switching transistor M1 is asymmetric, it can ensure that the source and drain of other transistors in this unit are connected to the bias voltage Vdd, ensuring that they are in the off state, thereby ensuring that the switch branch of the RF switch unit 100b is in the "OFF" state.
[0049] When the input signal path is connected to any RF switch unit as the output signal path, the other RF switch units are turned off, for example Figure 6 At this time, the output power of the RF switch network Pout = (N-1)*[2*(Vdd+Vth)] 2 / Zo+[2*(Vth)] 2 / Zo, where Vdd is the source-drain voltage, Vth is the threshold voltage of the switching transistor, N is the number of switching transistors cascaded in the RF switch unit, and Zo is the characteristic impedance of the RF working environment in which the RF switch unit is located, which is generally 50 ohms.
[0050] In other embodiments, the switch network may include n RF switch units, wherein one RF switch unit serves as an input signal path, and the remaining n-1 RF switch units serve as switchable output signal paths, respectively, and the target ports of the n RF switch units are connected; wherein n≥3.
[0051] In the above embodiment, by disconnecting the input / output terminal of the transistor of the RF switch unit connected to the network cross node from the source-drain voltage, the voltage requirements of each RF switch unit at the cross node in different switching states do not conflict, ensuring that the RF switch unit in the "OFF" state can maintain the "OFF" state, thereby improving the output power of the RF switch network.
[0052] An embodiment of the present application further provides a circuit structure, which includes the radio frequency switch unit in the above embodiment and at least one circuit branch. One end of the circuit branch is connected to the target port of the radio frequency switch unit to form a cross node VM; the voltage at the cross node VM is affected by the circuit branch.
[0053] In some embodiments, the circuit branch has an equivalent DC path from the crossover node to another voltage source. For example, the circuit branch may include an inductor or other DC path connected in series between the crossover node and ground.
[0054] Please refer to Figure 7 In the embodiment, two RF switch units 100 and a circuit branch 200 are used. In this embodiment, the circuit branch 200 is a RF impedance matching network with a bandpass filter function. Since the inductor has a path to the ground, the DC potential of the cross node VM is "0". And because the S end of the first switch transistor in the RF switch unit 100 is not forcibly set with a bias voltage, it can be biased to 0 with the VM DC, and the bias state of all other switch transistors in the unit is in a safe and stable "OFF" state, so that a larger and more stable RF output power is obtained in a smaller circuit layout area.
[0055] In other embodiments, when the circuit structure is in working state, the circuit branch and the RF switch unit have different voltage requirements for the cross node. Since the target port of the RF switch unit is disconnected from the source-drain voltage, the voltage at the cross node will not be affected by the source-drain voltage used to provide the bias voltage, so that the RF switch unit can operate in a normal bias state.
[0056] The above descriptions are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structural or equivalent process transformations made using the contents of the specification and drawings of the present application, such as the mutual combination of technical features between the embodiments, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.
Claims
1. A radio frequency switch unit, It is characterized in that include: A switch path composed of a plurality of cascaded switch transistors, wherein the gates of the switch transistors are electrically connected to a gate voltage through a gate resistor, the body electrodes are electrically connected to a body voltage through a body resistor, and the source / drain of the switch transistor is connected in sequence to the source / drain of an adjacent switch transistor; A source / drain of at least one switching transistor located at the end of the switching path is connected to the source / drain of an adjacent switching transistor, and the source / drain of the other switching transistors is electrically connected to the source-drain voltage through a bias resistor; The source / drain on the other side, as the target port of the switch path, is disconnected from the source-drain voltage and is used to be connected to a line cross node of the circuit network.
2. The radio frequency switch unit according to claim 1, It is characterized in that The voltage at the cross node is affected by another circuit branch other than the radio frequency switch unit and connected to the cross node.
3. A radio frequency switching network, It is characterized in that include: At least three radio frequency switch units according to any one of claims 1 to 2; The target ports of the switch paths of the various RF switch units are connected to each other to form a cross node of the RF switch network.
4. The radio frequency switch network according to claim 3, It is characterized in that The other end of the switch path of the radio frequency switch unit other than the cross node serves as a signal input end or a signal output end.
5. The radio frequency switch network according to claim 4, It is characterized in that The signal input end and the signal output end of the radio frequency switch network are both connected in series with a DC blocking capacitor.
6. The radio frequency switch network according to claim 4, It is characterized in that The switch network includes n radio frequency switch units. When the radio frequency switch network works normally, at least two of the radio frequency switch units are in different working states, and n≥3.
7. The radio frequency switch network according to claim 6, It is characterized in that Among the n RF switch units, at least one RF switch unit is used as an input signal path, and the remaining RF switch units are respectively used as switchable output signal paths; when one of the input signal paths is connected to any one of the RF switch units used as the output signal path, and the other RF switch units are closed, the output power of the switch network is: Pout=(N-1)*[2*(Vdd+Vth)] 2 / Zo+[2*(Vth)] 2 / Zo, wherein Vdd is the source-drain voltage, Vth is the threshold voltage of the switching transistor, N is the number of switching transistors cascaded in the RF switch unit, and Zo is the characteristic impedance of the RF working environment in which the RF switch unit is located.
8. A circuit structure, It is characterized in that include: The radio frequency switch unit according to any one of claims 1 to 2, and at least one circuit branch; One end of the circuit branch is connected to the target port of the radio frequency switch unit to form a cross node; The voltage at the cross node is affected by the circuit branch.
9. The circuit structure according to claim 8, It is characterized in that The circuit branch has an equivalent DC path from the crossover node to another voltage source.
10. The circuit structure according to claim 8, It is characterized in that When the circuit structure is in a working state, the circuit branch and the radio frequency switch unit have different voltage requirements on the cross node.