A voltage-controlled attenuator and radio frequency chip

Abstract

The present disclosure relates to the field of integrated circuits. To address the problem of large attenuation slope errors in voltage-controlled attenuators, a voltage-controlled attenuator and radio frequency chip are provided. The attenuation slope error of the voltage-controlled attenuator is reduced, comprising a signal attenuation circuit and a first control circuit. The first control circuit comprises a current mirror structure having an input branch and an output branch, wherein the output branch replicates the current of the input branch. The input branch comprises a first transistor, wherein a first resistor is connected between the output end of the first transistor and a standard ground, and the output end of the first transistor is connected to an external voltage interface. The output branch comprises a second transistor, wherein an analog branch is connected between the output end of the second transistor and the standard ground, and the analog branch has the same structure as the attenuation branch in the signal attenuation circuit. The attenuation branch comprises a third transistor, wherein the control end of the third transistor is directly or indirectly connected to the output end of the second transistor. The voltage-controlled attenuator has a reduced attenuation slope error.

Description

Technical Field

[0001] The present disclosure relates to the field of integrated circuits, and in particular to a voltage-controlled attenuator and a radio frequency chip. Background Art

[0002] An RF attenuator is a passive device primarily used to reduce the strength of RF signals and improve impedance matching. It is widely used in communication systems, instrumentation, and various test systems. RF attenuators are specifically categorized as digital attenuators and voltage-controlled attenuators (VVAs). A voltage-controlled attenuator is a module that continuously adjusts the network attenuation value by changing the conduction state of an internal transistor based on an externally input main control voltage. It is typically used in RF links or low-frequency power regulation circuits. A linear voltage-controlled attenuator is a subdivision of a voltage-controlled attenuator that utilizes the impedance characteristics of the transistor's linear region to achieve a linear relationship between attenuation and the main control voltage (i.e., the slope of attenuation as the main control voltage changes is fixed).

[0003] However, due to temperature and process errors, current linear voltage-controlled attenuators always have attenuation slope errors (that is, the slope of the attenuation as the main control voltage changes is not completely fixed), which affects the overall performance of the device. Summary of the Invention

[0004] To address the problem of large fluctuations in the attenuation slope of a voltage-controlled attenuator, the present disclosure provides a voltage-controlled attenuator and a radio frequency chip.

[0005] The technical solution of the present disclosure is achieved as follows:

[0006] In a first aspect, an embodiment of the present disclosure provides a voltage-controlled attenuator, comprising:

[0007] a signal attenuation circuit, the signal attenuation circuit comprising a transmission trunk and an attenuation branch, the transmission trunk being connected to the radio frequency link, the attenuation branch being connected to the transmission trunk; the signal attenuation circuit being configured to attenuate the radio frequency signal in the transmission trunk via the attenuation branch;

[0008] A first control circuit includes: a current mirror structure; the current mirror structure has an input branch and an output branch, the output branch replicating the current of the input branch; the input branch includes a first transistor, a first resistor is connected between the output end of the first transistor and a standard ground, and the output end of the first transistor is connected to an external voltage interface; the output branch includes a second transistor, an analog branch is connected between the output end of the second transistor and the standard ground, and the analog branch has the same structure as the attenuation branch;

[0009] The attenuation branch includes a third transistor, and a control terminal of the third transistor is directly or indirectly connected to the output terminal of the second transistor.

[0010] In this way, an analog branch is introduced into the first control circuit, and the analog branch and the attenuation branch have the same device electrical performance information μ o C ox , so that the voltage at the output of the second transistor contains the electrical performance information μ o C ox When this voltage is used to control the third transistor, it will offset the device electrical performance information μ of the third transistor. o C ox Therefore, within the linear operating range, the degree of opening of the third transistor and the voltage at the output of the second transistor present a more accurate linear relationship, and there is no o C ox The additional attenuation slope error introduced by different values ​​at different temperatures realizes temperature compensation of the attenuation slope.

[0011] In some embodiments, the output terminal of the first transistor is directly connected to the external voltage interface;

[0012] or,

[0013] The first control circuit further includes: a clamping circuit; the clamping circuit is connected to the external voltage interface and the output end of the first transistor respectively, and is configured to clamp the voltage value of the output end of the first transistor to the voltage value of the external voltage interface.

[0014] In this way, if the voltage value of the external voltage interface can be given to the output end of the first transistor without loss, the output end of the first transistor is directly connected to the external voltage interface, and the structure is simple; if the voltage value of the external voltage interface cannot be given to the output end of the first transistor without loss, the clamping circuit is used to make the voltage at the output end of the first transistor the same as the voltage of the external voltage interface, thereby avoiding transmission loss and further reducing the fluctuation of the attenuation slope.

[0015] In some embodiments, the first control circuit further includes: a voltage regulation circuit; the voltage regulation circuit is connected to the output end of the second transistor and is configured to regulate the voltage of the output end of the second transistor to a preset voltage range to generate a main control voltage; the control end of the third transistor receives the main control voltage.

[0016] In this way, the voltage regulating circuit regulates the voltage value of the output terminal of the second transistor to be within the linear working range corresponding to the attenuation branch, thereby driving the attenuation branch to work and accurately regulating its attenuation amount.

[0017] In some embodiments, the resistance of the first resistor is adjustable; and / or the temperature coefficient of the first resistor is less than or equal to a preset value.

[0018] In this way, by calibrating the resistance of the first resistor, the attenuation slope can be shifted, compensating for the simulation error of the transistor threshold voltage, and further compensating for the attenuation slope error caused by temperature. In addition, the effect of temperature on the resistance of the first resistor is almost negligible, avoiding the introduction of additional errors.

[0019] In some embodiments, the first resistor includes a resistor array consisting of a plurality of resistors.

[0020] In this way, the resistance of the first resistor can be flexibly adjusted at a low cost.

[0021] In some embodiments, the analog branch includes an analog transistor, which has the same device type and width-to-length ratio as the third transistor; the control terminal of the analog transistor receives a fixed voltage, and the fixed voltage is greater than the threshold voltage of the analog transistor.

[0022] In this way, by fixing the voltage, the analog branch is in a fixed working state, so that the voltage at the output end of the second transistor carries electrical performance information.

[0023] In a second aspect, an embodiment of the present disclosure provides a radio frequency chip, which includes the voltage-controlled attenuator as described in the first aspect.

[0024] For the radio frequency chip, the error of the attenuation slope of the voltage-controlled attenuator therein is small and has a stable port standing wave. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the position of a signal attenuation circuit provided in an embodiment of the present disclosure;

[0026] Figure 2 A schematic structural diagram of a signal attenuation circuit provided in an embodiment of the present disclosure;

[0027] Figure 3 A schematic diagram showing the change of equivalent resistance of a transistor with gate voltage;

[0028] Figure 4 This is an equivalent schematic diagram of a signal attenuation circuit provided by an embodiment of the present disclosure;

[0029] Figure 5 A schematic structural diagram of a first voltage-controlled attenuator example 1 provided in an embodiment of the present disclosure;

[0030] Figure 6 A detailed structural diagram of Example 2 of the first voltage-controlled attenuator provided in an embodiment of the present disclosure;

[0031] Figure 7 A schematic structural diagram of a second voltage-controlled attenuator provided in an embodiment of the present disclosure;

[0032] Figure 8 A schematic structural diagram of a third voltage-controlled attenuator provided in an embodiment of the present disclosure;

[0033] Figure 9 Schematic diagrams of several current mirror structures provided in embodiments of the present disclosure;

[0034] Figure 10 A schematic diagram of an application scenario of the first voltage-controlled attenuator provided in an embodiment of the present disclosure;

[0035] Figure 11 A schematic structural diagram of a second control circuit provided in an embodiment of the present disclosure;

[0036] Figure 12 The simulation results of a voltage-controlled attenuator provided by the embodiment of the present disclosure are shown as follows Figure 1 ;

[0037] Figure 13 The simulation results of a voltage-controlled attenuator provided by the embodiment of the present disclosure are shown as follows Figure 2 ;

[0038] Figure 14 A schematic diagram of the structure of a radio frequency chip provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0039] The following, in conjunction with the accompanying drawings, provides a clear and complete description of the technical solutions in the embodiments of the present disclosure. It should be understood that the specific embodiments described herein are intended solely to illustrate the related applications and are not intended to limit those applications. It should also be noted that, for ease of description, only portions of the drawings related to the related applications are shown. Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which the present disclosure relates. The terms used herein are for the purpose of describing the embodiments of the present disclosure only and are not intended to limit the present disclosure. In the following description, references to "some embodiments" describe a subset of all possible embodiments. However, it should be understood that "some embodiments" may refer to the same or different subsets of all possible embodiments and may be combined with each other without conflict. It should be noted that the terms "first," "second," and "third" in the embodiments of the present disclosure are used solely to distinguish similar objects and do not represent a specific ordering of the objects. It should be understood that "first," "second," and "third" may be interchanged in a specific order or sequential order, where permitted, to enable the embodiments of the present disclosure described herein to be implemented in an order other than that illustrated or described.

[0040] The voltage-controlled attenuator is a common component in RF links. Its main function is to adjust the strength of the RF signal. The core of the voltage-controlled attenuator is the signal attenuation circuit. Figure 1 , which shows a schematic diagram of the position of the signal attenuation circuit 20 in the radio frequency link. Figure 1 As shown, the signal attenuation circuit 20 is connected in series between the first RF module 11 and the second RF module 12 and is generally a passive device. The signal attenuation circuit 20 has various structures, such as a T-type network, a π-type network, a bridge T-type network, etc.

[0041] Take T-type network as an example, see Figure 2 , which shows a schematic structural diagram of a signal attenuation circuit 20 using a T-type network. Figure 2 As shown, the signal attenuation circuit 20 includes a T-shaped transmission trunk and an attenuation branch. The transmission trunk includes transistors M1 and M2 connected in series, and the attenuation branch includes transistor M3. The input of transistor M1 serves as the RF input terminal RFin to receive RF signals, and the output of transistor M2 serves as the RF output terminal RFout to output RF signals. The input of transistor M3 is connected to the output of transistor M1, and the output of transistor M3 is connected to the standard ground. In this way, the RF signal is transmitted via the transmission trunk, and part of the signal is transmitted to ground via the attenuation branch, achieving the attenuation function.

[0042] In terms of control, the control end of transistor M3 receives the main control voltage Vctrl, which is generally an external input. The control ends of transistor M1 and transistor M2 receive the feedback control voltage Vtune. Overall, transistor M3 can be equivalent to a variable resistor, whose resistance changes with the voltage of the main control voltage Vctrl. Transistor M1 and transistor M2 can be equivalent to variable resistors or replaced with fixed resistors. The voltage of the main control voltage Vctrl can determine the attenuation amount when the T-type attenuation circuit is working. The voltage value of the main control voltage Vctrl is usually continuous, so that the impedance of the attenuation branch changes continuously, which is called a voltage-controlled attenuator. In addition, the voltage value of the feedback control voltage Vtune changes with the voltage value of the main control voltage Vctrl, and the two show a negative correlation. The feedback control voltage Vtune is used to ensure impedance matching between the voltage-controlled attenuator and the front and rear RF devices, thereby ensuring the best standing wave characteristics.

[0043] See Figure 3 , which shows a schematic diagram of the change of equivalent resistance of a transistor with gate voltage. Figure 3In the figure, the horizontal axis (X-axis) is the gate voltage Vg, and the vertical axis (Y-axis) is the equivalent resistance. As the gate voltage Vg increases, the equivalent resistance of the transistor gradually decreases. For the portion outlined by the dashed line, the equivalent resistance of transistor M3 exhibits a roughly linear relationship with changes in gate voltage. In other words, by limiting the voltage range of the main control voltage Vctrl, the resistance of transistor M3 maintains a linear change, resulting in a nearly linear relationship between network attenuation and the main control voltage.

[0044] Please refer to Figure 4 , which is a simplified schematic diagram of the signal attenuation circuit 20. The resistance of the transistor M3 is As shown in formula (1), the attenuation of the signal attenuation circuit 20 is As shown in formula (2), the attenuation slope of the signal attenuation circuit 20 is As shown in formula (3).

[0045] …… ...

[0046] in, refers to the aspect ratio of transistor M3, is the gate-source voltage difference of transistor M3, is the threshold voltage of transistor M3, μ o C ox Refers to the electrical performance information of the transistor, μ o is the electron mobility and is affected by temperature, C ox is the gate oxide capacitance per unit area.

[0047] …… ...

[0048] ………………………………(3)

[0049] From formula (1) to formula (3), it can be seen that the attenuation slope The electrical performance information μ of transistor M3 o C ox Related to, and also related to, the overdrive voltage (V gs -V T ), RK in formula (3) is a simplified representation of the relationship between some parameters that are less concerned, which can be derived from formulas (1) and (2). R refers to other resistances or line resistances in the circuit and can be regarded as a constant.

[0050] As an engineering product, it is desirable for the attenuation slope to remain constant within the operating voltage and temperature range. Therefore, achieving a linear voltage-controlled attenuator with low attenuation slope error is very meaningful from an engineering perspective.

[0051] Therefore, the present disclosure aims to provide a voltage-controlled attenuator with low attenuation slope error, which has stable operating performance under different operating temperatures and is of great significance from an engineering perspective.

[0052] The embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0053] In one embodiment of the present disclosure, see Figure 5 , which shows a schematic structural diagram of a voltage-controlled attenuator 200 provided by an embodiment of the present disclosure. Figure 5 As shown, the voltage controlled attenuator 200 includes a signal attenuation circuit 20 and a first control circuit 21 .

[0054] See Figure 5 The signal attenuation circuit 20 includes a transmission trunk 201 and an attenuation branch 202. The transmission trunk 201 is connected to the RF link (i.e., between the RF input port RFin and the RF output port RFout), and the attenuation branch 202 is connected to the transmission trunk 201. The signal attenuation circuit 20 is configured to attenuate the RF signal in the transmission trunk 201 via the attenuation branch 202. Thus, the transmission trunk 201 in the voltage-controlled attenuator 200 primarily transmits the RF signal, while the attenuation branch 202 releases some of the energy elsewhere, thereby achieving signal attenuation. The operating parameters of the attenuation branch 202 determine the amount of RF signal attenuation.

[0055] See Figure 5 The first control circuit 21 includes a current mirror structure 212, which has an input branch 212a and an output branch 212b. The output branch 212b replicates the current of the input branch 212a. The input branch 212a has a first transistor 31. A first resistor 34 is connected between the output end of the first transistor 31 and the standard ground, and the output end N1 of the first transistor 31 is connected to an external voltage interface (the voltage value of the external voltage interface is Vm). The output branch 212b has a second transistor 32. An analog branch 33 is connected between the output end N2 of the second transistor 32 and the standard ground. The analog branch 33 has the same structure as the attenuation branch 202.

[0056] The attenuation branch 202 includes a third transistor 53 , and a control terminal of the third transistor 53 is directly or indirectly connected to the output terminal N2 of the second transistor 32 .

[0057] It should be understood that for a transistor, the control terminal refers to the gate, the input terminal refers to one of the drain and the source, and the output terminal refers to the source and the other of the source. The input terminal and the output terminal can be interchanged depending on the actual current flow direction.

[0058] It should be noted that, for the signal attenuation circuit 20, the electrical performance information μ of the circuit components iso C ox Different error values ​​(μ o The specific value of is affected by temperature), resulting in the attenuation slope being non-linear. In the embodiment of the present disclosure, the voltage provided by the external voltage interface is denoted as Vm, the output terminal N1 of the first transistor 31 is connected to the external voltage interface, that is, the voltage value at N1 is Vm, and the resistance value of the first resistor 34 is denoted as Rref. At this time, the current I1 at N1 is as shown in formula (4), and the current mirror structure 212 copies the current I1 at N1 to N2. Taking the copy ratio of the current mirror structure 212 as 1:1 as an example, at this time, the current I2 at N2 is the same as the current I1 at N1, also as shown in formula (4). The current I2 is converted into a voltage V2 via the analog branch 33, and the voltage V2 carries the electrical performance information μ of the device in the analog branch 33. o C ox , as shown in formula (5).

[0059] I2=I1=Vm / Rref………………………………(4)

[0060] V2=I2×Rds= ≈ ……………(5)

[0061] The analog branch 33 can be abstracted as a transistor, Rds refers to the equivalent resistance of the analog branch 33, W3 / L3 refers to the width-to-length ratio of the analog branch 33, is the threshold voltage of the analog branch 33. The 2.5 in formula (5) assumes that the control terminal of the analog branch 33 receives a voltage of 2.5V, and Much less than 2.5V.

[0062] In the embodiment of the present disclosure, the circuit structures of the analog branch 33 and the attenuation branch 202 are the same, so the electrical performance information of the third transistor 53 in the attenuation branch 202 is also μ o C ox , and the width-to-length ratio of the third transistor 53 is W3 / L3. Since the resistance Rds2 of the third transistor 53 is also affected by the electrical performance information μ o C ox and the influence of voltage V2 (voltage V2 is directly or indirectly given to the control terminal of the third transistor 53), thereby controlling the electrical performance information μ carried by the voltage V2 at the control terminal. o C ox and the electrical performance information μ of the device in the attenuation branch 202 o C ox The resistance Rds2 of the third transistor 53 is not affected by the electrical performance information μ o C oxThe influence of can be seen in formula (6). According to formula (6), the resistance Rds2 of the third transistor 53 is only related to the resistance Rref of the first resistor 34 and the voltage Vm of the external voltage interface, and is not related to μ o C ox related, will not be affected by the electrical performance information μ at different temperatures o C ox Different error is introduced to compensate for the attenuation slope error caused by the electrical performance information of the device at different temperatures.

[0063] Rds2= …………(6)

[0064] Here, Vth refers to the threshold voltage of the resistance Rds2 of the third transistor 53 .

[0065] Attenuation of the voltage-controlled attenuator 200 As shown in formula (7). According to formula (7), since Rds2 is related to the electrical performance information μ o C ox It has nothing to do with the attenuation. and electrical performance information μ o C ox At the same time, for a specific voltage-controlled attenuator 200, Rref is a fixed value, so the attenuation It can be considered that the attenuation slope changes with Vm Will behave as a fixed value.

[0066] ………………………………(7)

[0067] Where R is a constant, representing the resistance in the circuit or the resistance of the line itself.

[0068] It should be understood that the above formula is an ideal case and is affected by the actual device and working environment. There will still be fluctuations. However, the fluctuations in the attenuation slope of the voltage-controlled attenuator 200 provided by the present disclosure are significantly reduced. Thus, the performance of the voltage-controlled attenuator 200 provided by the embodiment of the present disclosure is more stable, and its application in electronic devices will provide them with more stable operating conditions and better output performance.

[0069] In some embodiments, the circuit device size of the analog branch 33 is the same as the circuit device size of the attenuation branch 202 (within the allowable error range), thereby better offsetting the device electrical performance information and reducing the attenuation slope error of the voltage-controlled attenuator 200.

[0070] For details, see Figure 5The analog branch 33 includes an analog transistor 331, which has the same device type and width-to-length ratio as the third transistor 53; the control end of the analog transistor 331 receives a fixed voltage Vs, and the fixed voltage Vs is greater than the threshold voltage of the analog transistor 331, so that the analog transistor 331 has the characteristics of a switch.

[0071] The value of the fixed voltage is determined according to actual device parameters. For example, the fixed voltage Vs is 2.5V.

[0072] In some embodiments, please refer to Figure 5 , the voltage value Vm of the external voltage interface can be transmitted to N1 almost losslessly. At this time, the output terminal N1 of the first transistor 31 is directly connected to the external voltage interface.

[0073] In other embodiments, if the voltage value Vm of the external voltage interface is directly transmitted to N1, there will be errors, resulting in the voltage received by N1 not being Vm. Therefore, please refer to Figure 6 The first control circuit 21 further includes a clamping circuit 211; the clamping circuit 211 is connected to the external voltage interface and the output terminal N1 of the first transistor 31 respectively, and is configured to clamp the voltage value of the output terminal of the first transistor 31 to the voltage value Vm of the external voltage interface.

[0074] It should be noted that the clamping circuit 211 can be implemented by an operational amplifier.

[0075] See Figure 6 The clamping circuit 211 includes a first operational amplifier 2111 , a first input terminal of the first operational amplifier 2111 is connected to the external voltage interface, and a second input terminal of the first operational amplifier 2111 is connected to the output terminal N1 of the first transistor 31 .

[0076] It should be noted that the output terminal of the first operational amplifier 2111 is connected to the control terminal of at least one transistor in the input branch 212a, thereby achieving a voltage clamping function through feedback adjustment. In particular, since the input branch 212a may include multiple transistors, the first operational amplifier 2111 may need to be connected to the output terminals of different transistors depending on the different structures of the input branch 212a.

[0077] In a specific embodiment, Figure 6 As shown, the current mirror structure 212 includes a first transistor 31 and a second transistor 32; the input end of the first transistor 31 receives the power supply voltage VDD, the input end of the second transistor 32 receives the power supply voltage VDD; the control end of the first transistor 31 is connected to the control end of the second transistor 32.

[0078] At this time, the output terminal of the first operational amplifier 2111 is connected to the control terminal of the first transistor 31 .

[0079] In addition, the clamping circuit 211 can also be implemented by structures such as diodes, capacitors, resistors, or a dedicated clamping IC.

[0080] In another specific embodiment, Figure 7 As shown, the current mirror structure 212 includes a first transistor 31, a second transistor 32, and a fourth transistor 35. The first transistor 31 and the fourth transistor 35 are connected in series in the input branch 212a, and the second transistor 32 is connected in series in the output branch 212b. The input terminal of the first transistor 31 and the input terminal of the second transistor 32 both receive the power supply voltage VDD. The control terminal of the first transistor 31, the output terminal of the first transistor 31, the control terminal of the second transistor 32, and the input terminal of the fourth transistor 35 are connected. In this case, the output terminal of the first operational amplifier 2111 is connected to the control terminal of the fourth transistor 35, and the fourth transistor 35 is connected to the first resistor 34. The driving terminal of the first operational amplifier receives the power supply signal VDD.

[0081] for Figure 7 , the first resistor 34 is indirectly connected to the output end of the first transistor 31 .

[0082] In another specific embodiment, Figure 8 As shown, the current mirror structure 212 includes a first transistor 31, a second transistor 32 and a fourth transistor 35, the control end of the first transistor 31 is connected to the control end of the second transistor 32, the output end of the first transistor 31 is connected to the input end of the fourth transistor 35, the control end of the fourth transistor 35 is connected to its own output end, the output end of the fourth transistor 35 is connected to the first resistor 34, and the output end of the first operational amplifier 2111 is connected to the control end of the first transistor 31.

[0083] In the above embodiment, the first transistor 31 and the second transistor 32 are both PMOS transistors. Figure 9 Several other types of PMOS current mirrors are also shown (not all of them are complete). In addition, NMOS current mirrors can also be used to form current mirrors, and their specific structure needs to match the selected transistor type.

[0084] It can be seen from the above that there are various types of current mirror structures 212 , and the specific connection method of the clamping circuit 211 only needs to match the current mirror structure 212 .

[0085] In some embodiments, see Figure 6The first control circuit 21 also includes a voltage regulation circuit 213. The voltage regulation circuit 213 is connected to the output terminal N2 of the second transistor 32 and is configured to regulate the voltage of the output terminal N2 of the second transistor 32 to a preset voltage range (i.e., the linear operating voltage range of the attenuation branch 53) to generate a main control voltage Vctrl; the control terminal of the third transistor 53 receives the main control voltage Vctrl.

[0086] In one example, the voltage regulating circuit 213 can amplify / reduce the voltage V2 at N2 to obtain the main control voltage Vctrl, so that within the preset voltage range, the voltage value of the main control voltage Vctrl is multiple of the voltage V2 at N2, completely offsetting the electrical performance information μ of the device in the attenuation branch 202. o C ox , the attenuation slope fluctuation of the voltage-controlled attenuator 200 is small.

[0087] In this example, see Figure 6 The voltage regulation circuit 213 includes a second operational amplifier 41, a second resistor 42, and a third resistor 43. The first input terminal of the second operational amplifier 41 is connected to the output terminal of the second transistor 32, and the output terminal of the second operational amplifier 41 (for outputting the main control signal Vctrl) is connected to the control terminal of the third transistor 53. The second terminal of the second resistor 42 and the first terminal of the third resistor 43 are connected to the second input terminal of the second operational amplifier 41. The first terminal of the second resistor 42 is connected to the output terminal of the second operational amplifier 41, and the second terminal of the third resistor 43 is connected to the standard ground. The driving terminal of the second operational amplifier 41 receives the power supply signal VDD.

[0088] In another example, the voltage regulating circuit 213 may include a diode chain, which utilizes the conduction voltage drop of the diode (generally 0.7V for silicon diodes and 0.3V for germanium diodes) to achieve voltage raising or lowering, so that the obtained main control voltage Vctrl is within the linear operating range of the voltage-controlled attenuator, while also carrying the electrical performance information μ o C ox .

[0089] See Figure 12 , which shows a conventional voltage-controlled attenuator (without the first control circuit 21, the third transistor 53 directly receives the voltage Vm of the external voltage interface) and the voltage-controlled attenuator 200 provided by the present disclosure (refer to Figure 6) Schematic diagrams showing the variation of the attenuation slope at three different temperatures. Specifically, curves a1, b1, and c1 are schematic diagrams showing the variation of the attenuation slope of a conventional voltage-controlled attenuator at 85°C, 25°C, and -40°C as a function of the external voltage interface Vm; curves a2, b2, and c2 are schematic diagrams showing the variation of the attenuation slope of the voltage-controlled attenuator 200 provided in the present disclosure at 85°C, 25°C, and -40°C as a function of the external voltage interface Vm.

[0090] like Figure 12 As shown, when the voltage Vm of the external voltage interface remains unchanged, the distance between curve a1 and curve c1 is significantly greater than the distance between curve a2 and curve c2. That is, when the voltage Vm of the external voltage interface remains unchanged, when the temperature changes, the attenuation slope of the traditional voltage-controlled attenuator changes greatly, while the attenuation slope of the voltage-controlled attenuator 200 disclosed in the present invention changes less, that is, the attenuation slope fluctuation of the voltage-controlled attenuator 200 disclosed in the present invention is smaller than the attenuation slope fluctuation of the traditional voltage-controlled attenuator. Figure 12 As shown, at the highest point of curve a1, the attenuation slope is approximately -1.7; at the lowest point of curve c1, the attenuation slope is approximately -6.3. Thus, the attenuation slope of a conventional voltage-controlled attenuator fluctuates approximately around 4.5. At Vm = 700 mV, at the highest point of curve a2, the attenuation slope is approximately -3.5; at the lowest point of curve c2, the attenuation slope is approximately -5.1. Thus, the attenuation slope of the voltage-controlled attenuator 200 of the present disclosure fluctuates approximately around 1.5.

[0091] In some embodiments, see Figure 6 , the resistance of the first resistor 34 is adjustable. In this way, the current I1 at N1 is adjustable, so that the current I2 at the second node generated by the replication is adjustable, and the resistance of the equivalent resistor Rds2 of the third transistor 53 is adjustable, see the aforementioned formula (6).

[0092] The attenuation of the voltage-controlled attenuator 200 is related to the equivalent resistance Rds2 of the third transistor 53. Therefore, while the main control voltage Vctrl remains unchanged, adjusting the resistance of the first resistor 34 can change the attenuation, adjust the specific value of the attenuation slope, and compensate for simulation errors in the transistor threshold voltage. Furthermore, it can compensate for attenuation slope errors caused by temperature and device batch errors. The resistance of the first resistor 34 can also be adjusted after shipment.

[0093] See Figure 13, which shows a schematic diagram of the attenuation slope of the voltage-controlled attenuator 200 provided by the embodiment of the present disclosure when the resistance value of the first resistor 34 is 5 different values. Specifically, curves a, b, c, d, and e are schematic diagrams of the attenuation slope changing with the external voltage interface Vm when the resistance value of the first resistor is 1.1R0, 1.05R0, R0, 0.95R0, and 0.9R0 respectively. R0 is a fixed value. Figure 13 The ambient temperature is fixed at room temperature. It can be seen that when the voltage Vm of the external voltage interface is fixed, the different resistance values ​​of the first resistor 34 will change the attenuation slope of the voltage-controlled attenuator 200. Compared with curve a (using the first resistor 34 with a resistance of 1.1R0), curve e (using the first resistor 34 with a resistance of 0.9R0) is shifted downward by approximately 0.5-1.

[0094] In this way, the embodiment of the present disclosure, on the one hand, offsets the device electrical performance information μ o C ox The attenuation slope fluctuation can be reduced by adjusting the resistance value of the first resistor 34 to make the attenuation slope consistent at various temperatures. On the other hand, the attenuation curve can be shifted by adjusting the resistance value of the first resistor 34. The resistance value of the first resistor 34 can be adjusted after the chip is produced to compensate for the differences in process batches.

[0095] In a specific example, the first resistor 34 includes a resistor array composed of a plurality of resistors, thereby achieving adjustable resistance.

[0096] In another specific example, the temperature coefficient of the first resistor 34 is less than or equal to a preset value, that is, the first resistor 34 is a low temperature coefficient resistor, which can further reduce the error introduced by the ambient temperature and reduce the batch problem caused by the device process error.

[0097] In another specific example, the first resistor 34 includes a resistor array composed of multiple low temperature coefficient resistors, which not only makes the resistance adjustable, but also makes the resistance of the first resistor 34 less affected by temperature, thus avoiding the introduction of additional errors.

[0098] In some embodiments, the signal attenuation circuit 20 uses a T-type network, see Figure 6 The transmission trunk 201 includes a fifth transistor 51 and a sixth transistor 52 connected in series. The connection point between the fifth transistor 51 and the sixth transistor 52 is also connected to the input end of the third transistor 53, and the output end of the third transistor 53 is connected to the standard ground; the control end of the fifth transistor 51 and the control end of the sixth transistor 52 both receive the feedback control voltage Vtune.

[0099] In other embodiments, the signal attenuation circuit 20 may also employ a π-type network. Since a π-type network has two symmetrical attenuation branches, the analog branch 33 may have the same structure and device dimensions as one of the attenuation branches. Alternatively, the signal attenuation circuit 20 may employ an L-type network, a bridge T-type network, or the like.

[0100] See Figure 10 The voltage-controlled attenuator 200 also includes a second control circuit 22, the input end of which is directly or indirectly connected to the output end of the second transistor 32 to receive the main control voltage Vctrl. The output end of the second control circuit 22 outputs a feedback control voltage Vtune; the feedback control voltage Vtune has an inversely proportional dynamic relationship with the main control voltage Vctrl, so that the signal attenuation circuit 20 is impedance-matched with the RF modules of the previous and subsequent stages to ensure standing wave stability. Here, impedance matching refers to the equivalent impedance matching of the RFin end of the signal attenuation circuit 20 with the equivalent impedance matching of the output end of the first RF module 11, and the equivalent impedance matching of the RFout end of the signal attenuation circuit 20 with the equivalent impedance matching of the input end of the second RF module 12.

[0101] In some embodiments, see Figure 11 , the second control circuit 22 includes:

[0102] Mirror attenuation circuit 221 has the same circuit structure as signal attenuation circuit 20. Mirror attenuation circuit 221 is directly or indirectly connected to the output terminal of the second transistor 32 (to receive the main control signal Vctrl). Mirror attenuation circuit 221 is also connected to the output terminal of the second control circuit 22 (to receive the feedback control voltage Vtune to implement feedback regulation). This allows mirror attenuation circuit 221 and signal attenuation circuit 20 to have the same operating state.

[0103] A second current mirror 222 includes an input branch and an output branch, wherein the output branch replicates the current of the input branch. The input branch includes a seventh transistor 61, and the output branch includes an eighth transistor 62. The output terminal N3 of the seventh transistor 61 is connected to the standard ground via the mirror attenuation circuit 221 and the first load 71 connected in sequence, and the output terminal N4 of the eighth transistor 62 is connected to the standard ground via the second adjustable load 72. The control terminal of the seventh transistor 61, the output terminal of the seventh transistor 61, and the control terminal of the eighth transistor 62 are connected. The input terminal of the seventh transistor 61 and the input terminal of the eighth transistor 62 both receive the power supply voltage VDD.

[0104] The third current mirror 223 and the second current mirror 222 have an input branch and an output branch, wherein the output branch replicates the current of the input branch; the input branch includes a ninth transistor 63, and the output branch includes a tenth transistor 64; the output terminal N5 of the ninth transistor 63 is connected to the standard ground via a third load 73, and the output terminal N6 of the tenth transistor 64 is connected to the standard ground via a fourth adjustable load 74; the control terminal of the ninth transistor 63, the output terminal of the ninth transistor 63, and the control terminal of the tenth transistor 64 are connected, and the input terminal of the ninth transistor 63 and the input terminal of the tenth transistor 64 both receive the power supply voltage VDD;

[0105] The comparison circuit 224 is configured to compare the voltage values ​​at the output terminal N4 of the eighth transistor 62 and the output terminal N6 of the tenth transistor 64 to generate a feedback control voltage Vtune.

[0106] Here, the first load 71 and the third load 73 have the same resistance value. Since the inter-stage matching impedance in the RF field is generally 50Ω, the resistance value of the first load 71 and the third load 73 can be 50Ω. The second adjustable load 72 and the fourth adjustable load 74 have the same structure. Exemplarily, the second adjustable load 72 and the fourth adjustable load 74 each include a transistor and a diode connected in series (or multiple diodes connected in series).

[0107] In addition, the second control circuit can also be implemented by a similar circuit structure and is not limited to the above circuit.

[0108] In the above description, "connection" includes direct connection or indirect connection. The first transistor to the tenth transistor and the analog transistor are abstract concepts and can actually include one or more independent transistor devices. For example, the first transistor can include multiple transistor devices connected in series and / or multiple transistor devices connected in parallel, and can even include a resistor. As long as the device formed as a whole has transistor-like operating characteristics, it can be considered as the first transistor. The same applies to other transistor concepts. In addition, the first resistor to the third resistor can also each include multiple resistor devices connected in series and / or in parallel.

[0109] In another embodiment of the present disclosure, see Figure 14 , which shows a schematic diagram of the composition structure of a radio frequency chip 80 provided in an embodiment of the present disclosure. Figure 14 As shown, the RF chip 80 at least includes the aforementioned voltage-controlled attenuator 200 .

[0110] The above are only preferred embodiments of the present disclosure and are not intended to limit the scope of protection of the present disclosure. It should be noted that in the present disclosure, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "includes a..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element. The above serial numbers of the embodiments of the present disclosure are for description only and do not represent the advantages and disadvantages of the embodiments. The methods disclosed in the several method embodiments provided in the present disclosure can be arbitrarily combined without conflict to obtain new method embodiments. The features disclosed in the several product embodiments provided in the present disclosure can be arbitrarily combined without conflict to obtain new product embodiments. The features disclosed in the several method or device embodiments provided in the present disclosure can be arbitrarily combined without conflict to obtain new method embodiments or device embodiments. The above are only specific implementation methods of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this disclosure, and they should all be covered by the protection scope of the present disclosure.

Claims

1. A voltage-controlled attenuator, characterized in that: include: A signal attenuation circuit, the signal attenuation circuit comprising a transmission trunk and an attenuation branch, the transmission trunk being connected to the radio frequency link, and the attenuation branch being connected to the transmission trunk; The signal attenuation circuit is configured to attenuate the radio frequency signal in the transmission trunk via the attenuation branch; A first control circuit includes: a current mirror structure; the current mirror structure has an input branch and an output branch, the output branch replicating the current of the input branch; the input branch includes a first transistor, a first resistor is connected between the output end of the first transistor and a standard ground, and the output end of the first transistor is connected to an external voltage interface; the output branch includes a second transistor, an analog branch is connected between the output end of the second transistor and the standard ground, and the analog branch has the same structure as the attenuation branch; The attenuation branch includes a third transistor, the control end of which is directly or indirectly connected to the output end of the second transistor; the analog branch includes an analog transistor, the control end of which receives a fixed voltage, and the fixed voltage is greater than the threshold voltage of the analog transistor.

2. The voltage-controlled attenuator according to claim 1, wherein: The output end of the first transistor is directly connected to the external voltage interface; or, The first control circuit further includes: a clamping circuit; The clamping circuit is connected to the external voltage interface and the output end of the first transistor respectively, and is configured to clamp the voltage value of the output end of the first transistor to the voltage value of the external voltage interface.

3. The voltage-controlled attenuator according to claim 1, wherein: The first control circuit further includes: a voltage regulating circuit; the voltage regulating circuit is connected to the output terminal of the second transistor and is configured to regulate the voltage of the output terminal of the second transistor to a preset voltage range to generate a main control voltage; The control terminal of the third transistor receives the main control voltage.

4. The voltage-controlled attenuator according to any one of claims 1 to 3, wherein: The resistance of the first resistor is adjustable; and / or, The temperature coefficient of the first resistor is less than or equal to a preset value.

5. The voltage-controlled attenuator according to claim 4, wherein: The first resistor includes a resistor array consisting of a plurality of resistors.

6. The voltage-controlled attenuator according to any one of claims 1 to 3, characterized in that: The analog transistor and the third transistor have the same device type and width-to-length ratio.

7. The voltage-controlled attenuator according to claim 2, wherein: The clamping circuit includes a first operational amplifier, a first input terminal of the first operational amplifier is connected to the external voltage interface, and a second input terminal of the first operational amplifier is connected to the output terminal of the first transistor; The output terminal of the first operational amplifier is connected to the control terminal of at least one transistor in the input branch.

8. The voltage-controlled attenuator according to claim 7, wherein: An input terminal of the first transistor receives a power supply voltage, and an input terminal of the second transistor receives a power supply voltage; The control end of the first transistor, the control end of the second transistor and the output end of the first operational amplifier are connected together.

9. The voltage-controlled attenuator according to claim 7, wherein: The current mirror structure also includes a fourth transistor. The first transistor and the fourth transistor are connected in series in the input branch. The input end of the first transistor and the input end of the second transistor both receive a power supply voltage. The control end of the first transistor, the output end of the first transistor, the control end of the second transistor, and the input end of the fourth transistor are connected. The output end of the fourth transistor is connected to the first resistor, and the output end of the first operational amplifier is connected to the control end of the fourth transistor.

10. The voltage-controlled attenuator according to claim 3, wherein: The voltage regulating circuit includes a second operational amplifier, a second resistor and a third resistor; The first input terminal of the second operational amplifier is connected to the output terminal of the second transistor, and the output terminal of the second operational amplifier is connected to the control terminal of the third transistor; The second end of the second resistor, the first end of the third resistor and the second input end of the second operational amplifier are connected; the first end of the second resistor is connected to the output end of the second operational amplifier, and the second end of the third resistor is connected to the standard ground.

11. The voltage-controlled attenuator according to any one of claims 1 to 3, wherein: The transmission trunk includes a fifth transistor and a sixth transistor connected in series, wherein a connection point between the fifth transistor and the sixth transistor is also connected to the input terminal of the third transistor, and the output terminal of the third transistor is connected to a standard ground; the control terminal of the fifth transistor and the control terminal of the sixth transistor both receive a feedback control voltage; The voltage-controlled attenuator also includes a second control circuit, the input end of the second control circuit is directly or indirectly connected to the output end of the second transistor, and the output end of the second control circuit outputs the feedback control voltage; the feedback control voltage has an inversely proportional dynamic relationship with the voltage of the output end of the second transistor.

12. A radio frequency chip, characterized in that: The radio frequency chip includes the voltage-controlled attenuator according to any one of claims 1 to 11.

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