Small-step adjustable broadband resistance attenuator

Abstract

The invention discloses a small-step adjustable broadband resistance attenuator, which relates to the technical field of attenuators and comprises a first port resistor, a second port resistor, a first-stage resistance attenuator and a second-stage resistance attenuator. One end of the first port resistor is connected with the anode of the current input port, and the other end is connected with a virtual ground point. One end of the second port resistor is connected with the cathode of the current input port, and the other end is connected with a virtual ground point. The first port resistor and the second port resistor play a role in impedance matching. The input end of the first-stage resistance attenuator is connected with the current input port, and the output end of the first-stage resistance attenuator is connected with the input end of the second-stage resistance attenuator. 2dB attenuation adjustment is realized by using a resistor shunting principle. And the output end of the second-stage attenuator is connected with the voltage output port of the integral attenuator. And the second-stage attenuator adopts an R-2R structure, so that 6dB attenuation adjustment can be realized, and meanwhile, high load impedance is supported. The whole attenuator can realize a 22dB attenuation adjustment range and 2dB adjustment stepping. Due to the fact that the output impedance of the attenuator is not greatly changed when the attenuations are different, the attenuator can be applied to a broadband scene.

Description

Technical Field

[0001] The invention relates to the technical field of attenuators, in particular to a broadband resistance attenuator which is adjustable in small steps. Background Art

[0002] In the industrial field, attenuators are widely used in chips, especially in communication transceiver chips, where they play important roles in adjusting signal size, current-to-voltage conversion, impedance matching, and increasing dynamic range.

[0003] Traditional baseband attenuators mainly use the R-2R ladder structure, which is suitable for circuits with high impedance in the subsequent input impedance, so it is often used in baseband circuits. And because of its inherent R-2R characteristics, the step length of the attenuator is 6dB, and it cannot be finely adjusted. Traditional RF attenuators can easily achieve small step-length precision adjustment, but they are only suitable for circuits with low impedance in the subsequent input impedance. Therefore, realizing an attenuator suitable for high impedance in the subsequent input impedance and adjustable in small steps is a major difficulty in attenuator design. Summary of the invention

[0004] In order to solve the deficiencies mentioned in the above background technology, the purpose of the present invention is to provide a broadband resistor attenuator with small step adjustable, which can support application scenarios with high load impedance and realize fine attenuation adjustment by combining resistor shunt and R-2R technology.

[0005] In the first aspect, the purpose of the present invention can be achieved by the following technical solution: a broadband resistance attenuator adjustable in small steps, comprising:

[0006] A first port resistor, a second port resistor, a first-stage resistor attenuator, and a second-stage resistor attenuator;

[0007] One end of the first port resistor is connected to the positive electrode of the current input port, and the other end is connected to the virtual ground point; one end of the second port resistor is connected to the negative electrode of the current input port, and the other end is connected to the virtual ground point;

[0008] The input end of the first-stage resistance attenuator is connected to the current input port, the output end of the first-stage resistance attenuator is connected to the input end of the second-stage resistance attenuator, and the output end of the second-stage attenuator is connected to the voltage output port of the overall attenuator.

[0009] In combination with the first aspect, in some implementations of the first aspect, the device further includes: the first-stage resistance attenuator includes a transistor M1, a transistor M2, a transistor M3, a transistor M4, a resistor R3, a resistor R4, a resistor R5, and a resistor R6;

[0010] One end of the resistor R3 is connected to the positive electrode Iin+ of the current input port, and the other end is connected to the drain of the transistor M1; the source of the transistor M1 is connected to the virtual ground point A; one end of the resistor R4 is connected to the negative electrode Iin- of the current input port, and the other end is connected to the drain of the transistor M2; the source of the transistor M2 is connected to the virtual ground point A; one end of the resistor R5 is connected to the positive electrode Iin+ of the current input port, and the other end is connected to the drain of the transistor M3; the source of the transistor M3 is connected to the virtual ground point A; one end of the resistor R6 is connected to the negative electrode Iin- of the current input port, and the other end is connected to the drain of the transistor M4; the source of the transistor M4 is connected to the virtual ground point A.

[0011] In combination with the first aspect, in some implementations of the first aspect, the device further includes: the second-stage resistance attenuator includes a switch S1, a switch S2, a switch S3, a switch S4, a switch S5, a switch S6, a switch S7, a switch S8, a resistor R7, a resistor R8, a resistor R9, a resistor R 10 , resistor R 11 , resistor R 12 , resistor R 13 , resistor R 14 , resistor R 15 , resistor R 16 , resistor R 17 , and resistor R 18 ;

[0012] The positive electrode Iin+ of the current input port, resistor R7, resistor R 11 , resistor R 15 The input ends of the switches S7 are connected in series, and the output end of the switch S7 is connected to the positive electrode Vout+ of the voltage output port; the input end of the switch S1 is connected to the positive electrode Iin+ of the current input port, and the input end of the switch S3 is connected to the resistor R7 and the resistor R 11 Connect node B, and the input of switch S5 is connected to resistor R 11 and resistor R 15 The node C connected, the output ends of switches S1, S3, and S5 are all connected to the positive electrode Vout+ of the voltage output port; one end of resistor R8 is connected to resistor R7 and resistor R 11 The other end of the resistor R is connected to the virtual ground point A. 12 One end of the resistor R 11 and resistor R 15 The other end of the resistor is connected to the virtual ground point A. 16 One end of the resistor R 15 The node D is connected to the input end of the switch S7, and the other end is connected to the virtual ground point A.

[0013] In combination with the first aspect, in some implementations of the first aspect, the device further includes: a negative electrode Iin- of the current input port, a resistor R 10 , resistor R 14 , resistor R 18 The input ends of the switches S8 are connected in series, the output end of the switch S8 is connected to the negative electrode Vout- of the voltage output port; the input end of the switch S2 is connected to the negative electrode Iin- of the current input port, and the input end of the switch S4 is connected to the resistor R 10 and resistor R 14 The node E is connected, and the input of switch S6 is connected to the resistor R 14 and resistor R 18 The node F connected, the output ends of switches S2, S4 and S6 are all connected to the negative electrode Vout- of the voltage output port; one end of resistor R9 is connected to resistor R 10 and resistor R 14 The other end of the resistor is connected to the virtual ground point A. 13 One end of the resistor R 14 and resistor R 18 The other end of the resistor is connected to the virtual ground point A. 17 One end of the resistor R 18 The node G connected to the input terminal of the switch S8 has the other end connected to the virtual ground point A.

[0014] In combination with the first aspect, in some implementations of the first aspect, the device further includes: the first port resistor R1, the second port resistor R2, a resistor R7, a resistor R 10 The resistance values ​​of resistors R3 and R4 are equal, and the resistance values ​​of resistors R5 and R6 are equal.

[0015] In combination with the first aspect, in certain implementations of the first aspect, the device further includes: the areas of the transistors M1, M2, M3, and M4 are equal, and all operate in a switching state, and the gate voltages are control voltage B1, control voltage B2, control voltage B3, and control voltage B4, respectively; when the control voltages B1 and B2 are switched from level 0 to level 1, the attenuation increases by 2dB; when the control voltages are switched from level 0 to level 1 at the same time, the attenuation increases by 4dB.

[0016] In combination with the first aspect, in some implementations of the first aspect, the device further includes: the switch S1, switch S2, switch S3, switch S4, switch S5, switch S6, switch S7, and switch S8 have the same structure, and include transistors M5 and M6; the drains of transistors M5 and M6 are connected as the input terminals IN of the switches, and the sources are connected as the output terminals OUT of the switches.

[0017] In combination with the first aspect, in some implementations of the first aspect, the device further includes: the transistor M5 is an N-type transistor, and the transistor M6 is a P-type transistor.

[0018] In combination with the first aspect, in some implementations of the first aspect, the device further includes: the resistor R7, the resistor R 10 , resistor R 11 , resistor R 14 , resistor R 15 , resistor R 18 , resistor R 16 , resistor R 17 The resistance values ​​of resistors R8, R9, and R 12 , resistor R 13 The resistance values ​​of resistor R8 are equal, and the resistance value of resistor R7 is twice that of resistor R7; when switch S1 and switch S2 are turned on and the other switches are not turned on, the second-stage resistor attenuator has no attenuation; when switch S3 and switch S4 are turned on and the other switches are not turned on, the attenuation of the second-stage resistor attenuator is 6dB; when switch S5 and switch S6 are turned on and the other switches are not turned on, the attenuation of the second-stage resistor attenuator is 12dB; when switch S7 and switch S8 are turned on and the other switches are not turned on, the attenuation of the second-stage resistor attenuator is 18dB.

[0019] Beneficial effects of the present invention:

[0020] The present invention utilizes the technology of combining resistor shunt and R-2R, which overcomes the disadvantage that the traditional R-2R ladder structure can only support 6dB step adjustment and cannot be finely adjusted, and can also be applied to circuits with high impedance in the subsequent input impedance. At the same time, based on the characteristic of small output impedance change, the attenuator has a good bandwidth. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 It is a structural schematic diagram of a broadband resistance attenuator with small-step adjustable width corresponding to the present invention;

[0023] Figure 2 is a circuit diagram of a switch circuit corresponding to the present invention;

[0024] Figure 3 It is a schematic diagram of a single-ended equivalent circuit of a resistor shunt attenuator of the present invention;

[0025] Figure 4 It is a schematic diagram of the R-2R ladder structure attenuator of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Embodiment 1:

[0028] like Figure 1 As shown, a broadband resistance attenuator adjustable in small steps comprises:

[0029] A first port resistor R1, a second port resistor R2, a first-stage resistor attenuator, and a second-stage resistor attenuator;

[0030] One end of the first-port resistor R1 is connected to the positive electrode Iin+ of the current input port, and the other end is connected to the virtual ground point A. One end of the second-port resistor R2 is connected to the negative electrode Iin- of the current input port, and the other end is connected to the virtual ground point A. The input end of the first-stage resistor attenuator is connected to the current input port Iin, and the output end is connected to the input end of the second-stage resistor attenuator, which uses the principle of resistor shunt to achieve 2dB attenuation adjustment. The output end of the second-stage attenuator is connected to the voltage output port Vout of the overall attenuator; the second-stage attenuator adopts an R-2R structure, which can achieve 6dB attenuation adjustment and support high load impedance.

[0031] The first-stage resistance attenuator includes a transistor M1, a transistor M2, a transistor M3, a transistor M4, a resistor R3, a resistor R4, a resistor R5, and a resistor R6;

[0032] One end of the resistor R3 is connected to the positive electrode Iin+ of the current input port, and the other end is connected to the drain of the transistor M1; the source of the transistor M1 is connected to the virtual ground point A; one end of the resistor R4 is connected to the negative electrode Iin- of the current input port, and the other end is connected to the drain of the transistor M2; the source of the transistor M2 is connected to the virtual ground point A; one end of the resistor R5 is connected to the positive electrode Iin+ of the current input port, and the other end is connected to the drain of the transistor M3; the source of the transistor M3 is connected to the virtual ground point A; one end of the resistor R6 is connected to the negative electrode Iin- of the current input port, and the other end is connected to the drain of the transistor M4; the source of the transistor M4 is connected to the virtual ground point A.

[0033] The second-stage resistance attenuator includes switch S1, switch S2, switch S3, switch S4, switch S5, switch S6, switch S7, switch S8, resistor R7, resistor R8, resistor R9, resistor R 10 , resistor R 11 , resistor R 12 , resistor R 13 , resistor R 14 , resistor R 15 , resistor R 16 , resistor R 17 , and resistor R 18 ;

[0034] The positive electrode Iin+ of the current input port, resistor R7, resistor R 11 , resistor R 15 The input ends of the switches S7 are connected in series, and the output end of the switch S7 is connected to the positive electrode Vout+ of the voltage output port; the input end of the switch S1 is connected to the positive electrode Iin+ of the current input port, and the input end of the switch S3 is connected to the resistor R7 and the resistor R 11 Connect node B, and the input of switch S5 is connected to resistor R 11 and resistor R 15 The node C connected, the output ends of switches S1, S3, and S5 are all connected to the positive electrode Vout+ of the voltage output port; one end of resistor R8 is connected to resistor R7 and resistor R 11 The other end of the resistor R is connected to the virtual ground point A. 12 One end of the resistor R 11 and resistor R 15 The other end of the resistor is connected to the virtual ground point A. 16 One end of the resistor R 15 The node D is connected to the input end of the switch S7, and the other end is connected to the virtual ground point A.

[0035] The negative electrode Iin- of the current input port, the resistor R 10 , resistor R 14 , resistor R 18 The input ends of the switches S8 are connected in series, the output end of the switch S8 is connected to the negative electrode Vout- of the voltage output port; the input end of the switch S2 is connected to the negative electrode Iin- of the current input port, and the input end of the switch S4 is connected to the resistor R 10 and resistor R 14 The node E is connected, and the input of switch S6 is connected to the resistor R 14 and resistor R 18 The node F connected, the output ends of switches S2, S4 and S6 are all connected to the negative electrode Vout- of the voltage output port; one end of resistor R9 is connected to resistor R 10 and resistor R 14The other end of the resistor is connected to the virtual ground point A. 13 One end of the resistor R 14 and resistor R 18 The other end of the resistor is connected to the virtual ground point A. 17 One end of the resistor R 18 The node G connected to the input terminal of the switch S8 has the other end connected to the virtual ground point A.

[0036] The first port resistor R1, the second port resistor R2, the resistor R7, the resistor R 10 The resistance values ​​of resistors R3 and R4 are equal, and the resistance values ​​of resistors R5 and R6 are equal.

[0037] The areas of the transistors M1, M2, M3 and M4 are equal, and they all work in a switching state, and their gate voltages are control voltage B1, control voltage B2, control voltage B3 and control voltage B4 respectively; when the control voltages B1 and B2 are switched from level 0 to level 1, the attenuation increases by 2dB; when the four control voltages are switched from level 0 to level 1 at the same time, the attenuation increases by 4dB.

[0038] like Figure 2 As shown, the switch S1, switch S2, switch S3, switch S4, switch S5, switch S6, switch S7, and switch S8 have the same structure, and include transistors M5 and M6; the drains of transistors M5 and M6 are connected as the input end IN of the switch, and the sources are connected as the output end OUT of the switch. The transistor M5 is an N-type transistor, and the transistor M6 is a P-type transistor.

[0039] Resistor R7, resistor R 10 , resistor R 11 , resistor R 14 , resistor R 15 , resistor R 18 , resistor R 16 , resistor R 17 The resistance values ​​of resistors R8, R9, and R 12 , resistor R 13 The resistance values ​​of resistor R8 are equal, and the resistance value of resistor R7 is twice that of resistor R7; when switch S1 and switch S2 are turned on and the other switches are not turned on, the second-stage resistor attenuator has no attenuation; when switch S3 and switch S4 are turned on and the other switches are not turned on, the attenuation of the second-stage resistor attenuator is 6dB; when switch S5 and switch S6 are turned on and the other switches are not turned on, the attenuation of the second-stage resistor attenuator is 12dB; when switch S7 and switch S8 are turned on and the other switches are not turned on, the attenuation of the second-stage resistor attenuator is 18dB.

[0040] Specifically, the present invention is further described below by way of embodiments:

[0041] like Figure 3 As shown in the figure, this circuit is a single-ended equivalent circuit diagram of a resistor shunt attenuator, where resistor R0 is the input port impedance and resistor R L is the load impedance; the resistor R 19 , switch S9, resistor R 20 , switch S 10 As an attenuation adjustment module.

[0042] When both switches are off, it can be calculated that

[0043] When only switch S9 is turned on, it can be calculated that

[0044] When switch S9, switch S 10 When both are conducting, we can calculate

[0045]

[0046] Therefore, when adjusting the switch, the current attenuation of this circuit will change, and the resistor R should be designed properly. 19 , resistor R 20 The value of can achieve fine attenuation adjustment, for example, setting the step size to 2dB can achieve 2dB and 4dB attenuation; the first-stage resistance attenuator in the present invention is designed based on this theory.

[0047] like Figure 4 As shown, the second-stage resistor attenuator in the present invention utilizes an R-2R ladder structure, and the circuit schematic diagram of the structure is shown in the figure; for the convenience of analysis, it is divided into n resistor units, namely cell1 to celln; the voltage gain of each unit is 1 / 2, so the voltage gain of n units can be obtained: That is -n×6dB; in addition, no matter how many resistance units there are, the input impedance of the circuit is fixed at 2R; the second-stage resistance attenuator uses 3 such resistance units to achieve a maximum voltage attenuation of 18dB, which controls the position of the output node through the switch to achieve attenuation adjustment of 0dB, 6dB, 12dB, and 18dB.

[0048] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0049] The above shows and describes the basic principles, main features and advantages of the present disclosure. Those skilled in the art should understand that the present disclosure is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present disclosure. Without departing from the spirit and scope of the present disclosure, the present disclosure may have various changes and improvements, and these changes and improvements fall within the scope of the present disclosure to be protected.

Claims

1. A broadband resistance attenuator with small step adjustable, characterized in that: include: A first port resistor, a second port resistor, a first-stage resistor attenuator, and a second-stage resistor attenuator; One end of the first port resistor is connected to the positive electrode of the current input port, and the other end is connected to the virtual ground point; one end of the second port resistor is connected to the negative electrode of the current input port, and the other end is connected to the virtual ground point; The input end of the first-stage resistance attenuator is connected to the current input port, the output end of the first-stage resistance attenuator is connected to the input end of the second-stage resistance attenuator, and the output end of the second-stage attenuator is connected to the voltage output port of the overall attenuator.

2. A broadband resistance attenuator with small step adjustable according to claim 1, characterized in that: The first-stage resistance attenuator includes a transistor M1, a transistor M2, a transistor M3, a transistor M4, a resistor R3, a resistor R4, a resistor R5 and a resistor R6; One end of the resistor R3 is connected to the positive electrode Iin+ of the current input port, and the other end is connected to the drain of the transistor M1; The source of transistor M1 is connected to virtual ground point A; one end of resistor R4 is connected to the negative electrode Iin- of the current input port, and the other end is connected to the drain of transistor M2; the source of transistor M2 is connected to virtual ground point A; one end of resistor R5 is connected to the positive electrode Iin+ of the current input port, and the other end is connected to the drain of transistor M3; the source of transistor M3 is connected to virtual ground point A; one end of resistor R6 is connected to the negative electrode Iin- of the current input port, and the other end is connected to the drain of transistor M4; the source of transistor M4 is connected to virtual ground point A.

3. The broadband resistance attenuator with small step adjustable according to claim 1, characterized in that: The second-stage resistance attenuator includes a switch S1, a switch S2, a switch S3, a switch S4, a switch S5, a switch S6, a switch S7, a switch S8, a resistor R7, a resistor R8, a resistor R9, a resistor R 10 , resistor R 11 , resistor R 12 , resistor R 13 , resistor R 14 , resistor R 15 , resistor R 16 , resistor R 17 , and resistor R 18 ; The positive electrode Iin+ of the current input port, resistor R7, resistor R 11 , resistor R 15 The input ends of switch S7 are connected in series, and the output end of switch S7 is connected to the positive electrode Vout+ of the voltage output port; the input end of switch S1 is connected to the positive electrode Iin+ of the current input port, and the input end of switch S3 is connected to the resistor R7 and the resistor R 11 Connect node B, and the input of switch S5 is connected to resistor R 11 and resistor R 15 The node C connected, the output ends of switches S1, S3, and S5 are all connected to the positive electrode Vout+ of the voltage output port; one end of resistor R8 is connected to resistor R7 and resistor R 11 The other end of the resistor R is connected to the virtual ground point A. 12 One end of the resistor R 11 and resistor R 15 The other end of the resistor is connected to the virtual ground point A. 16 One end of the resistor R 15 The node D is connected to the input end of the switch S7, and the other end is connected to the virtual ground point A.

4. A broadband resistance attenuator with small step adjustable according to claim 3, characterized in that: The negative electrode Iin- of the current input port and the resistor R 10 , resistor R 14 , resistor R 18 The input ends of the switches S8 are connected in series, the output end of the switch S8 is connected to the negative electrode Vout- of the voltage output port; the input end of the switch S2 is connected to the negative electrode Iin- of the current input port, and the input end of the switch S4 is connected to the resistor R 10 and resistor R 14 The node E is connected, and the input of switch S6 is connected to the resistor R 14 and resistor R 18 The node F connected, the output ends of switches S2, S4 and S6 are all connected to the negative electrode Vout- of the voltage output port; one end of resistor R9 is connected to resistor R 10 and resistor R 14 The other end of the resistor is connected to the virtual ground point A. 13 One end of the resistor R 14 and resistor R 18 The other end of the resistor is connected to the virtual ground point A. 17 One end of the resistor R 18 The node G connected to the input terminal of the switch S8 has the other end connected to the virtual ground point A.

5. The broadband resistance attenuator with small step adjustable according to claim 1, characterized in that: The first port resistor R1, the second port resistor R2, the resistor R7, the resistor R 10 The resistance values ​​of resistors R3 and R4 are equal, and the resistance values ​​of resistors R5 and R6 are equal.

6. The broadband resistance attenuator with small step adjustable according to claim 2, characterized in that: The areas of the transistors M1, M2, M3 and M4 are equal and all work in a switching state, and the gate voltages are control voltage B1, control voltage B2, control voltage B3 and control voltage B4 respectively; when the control voltages B1 and B2 are switched from level 0 to level 1, the attenuation increases by 2dB; when the control voltages are switched from level 0 to level 1 at the same time, the attenuation increases by 4dB.

7. The broadband resistance attenuator with small step adjustable according to claim 3, characterized in that: The switches S1, S2, S3, S4, S5, S6, S7 and S8 have the same structure and include transistors M5 and M6; The drains of the transistor M5 and the transistor M6 are connected to serve as the input terminal IN of the switch, and the sources are connected to serve as the output terminal OUT of the switch.

8. The broadband resistance attenuator with small step adjustable according to claim 7, characterized in that: The transistor M5 is an N-type transistor, and the transistor M6 is a P-type transistor.

9. The broadband resistance attenuator with small step adjustable according to claim 8, characterized in that: The resistor R7, the resistor R 10 , resistor R 11 , resistor R 14 , resistor R 15 , resistor R 18 , resistor R 16 , resistor R 17 The resistance values ​​of resistors R8, R9, and R 12 , resistor R 13 The resistance values ​​of resistor R8 are equal, and the resistance value of resistor R7 is twice that of resistor R7; when switch S1 and switch S2 are turned on and the other switches are not turned on, the second-stage resistor attenuator has no attenuation; when switch S3 and switch S4 are turned on and the other switches are not turned on, the attenuation of the second-stage resistor attenuator is 6dB; when switch S5 and switch S6 are turned on and the other switches are not turned on, the attenuation of the second-stage resistor attenuator is 12dB; when switch S7 and switch S8 are turned on and the other switches are not turned on, the attenuation of the second-stage resistor attenuator is 18dB.

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