Voltage-controlled attenuator and radio frequency chip

Abstract

The invention relates to the field of integrated circuits, and provides a voltage-controlled attenuator and a radio frequency chip in order to solve the problem that the attenuation slope error of the voltage-controlled attenuator is large, the voltage-controlled attenuator comprises a signal attenuation circuit and a first control circuit, and the first control circuit comprises a current mirror structure; the current mirror structure is provided with an input branch and an output branch, and the output branch copies the current of the input branch; the input branch is provided with a first transistor, a first resistor is connected between the output end of the first transistor and the standard ground, and the output end of the first transistor is connected with an external voltage interface; the output branch is provided with a second transistor, an analog branch is connected between the output end of the second transistor and the standard ground, and the analog branch and an attenuation branch in the signal attenuation circuit are the same in structure; the attenuation branch comprises a third transistor, and the control end of the third transistor is directly or indirectly connected with the output end of the second transistor. The attenuation slope error of the voltage-controlled attenuator is reduced.

Description

Technical Field

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

[0002] A radio frequency attenuator is a passive device mainly used to reduce the intensity of radio frequency signals and improve impedance matching, and is widely used in communication systems, instrument devices, and various test systems. Radio frequency attenuators are specifically divided into digital attenuators and voltage-controlled attenuators (VVA). A voltage-controlled attenuator is a module that changes the conduction state of internal transistors based on an externally input main control voltage, thereby continuously adjusting the network attenuation value, and is usually applied to radio frequency links or low-frequency power regulation circuits. A linear voltage-controlled attenuator is a subdivision of voltage-controlled attenuators, which utilizes the impedance characteristics of the linear region of transistors to achieve the effect that the attenuation amount has a linear relationship with the main control voltage (that is, the slope of the change in the attenuation amount with respect to the main control voltage is fixed).

[0003] However, due to temperature and process errors, there is always an attenuation slope error in current linear voltage-controlled attenuators (that is, the slope of the change in the attenuation amount with respect to the main control voltage is not completely fixed), resulting in an impact on the working performance of the overall device. Summary of the Invention

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

[0005] The technical solution of the present disclosure is implemented as follows: In a first aspect, an embodiment of the present disclosure provides a voltage-controlled attenuator, including: A signal attenuation circuit, the signal attenuation circuit includes a transmission main path and an attenuation branch, the transmission main path is connected in a radio frequency link, and the attenuation branch is connected to the transmission main path; the signal attenuation circuit is configured to attenuate the radio frequency signal in the transmission main path via the attenuation branch; A first control circuit, including: a current mirror structure; the current mirror structure has an input branch and an output branch, and the output branch replicates the current of the input branch; the input branch has a first transistor, a first resistor is connected between the output end of the first transistor and the standard ground, and the output end of the first transistor is connected to an external voltage interface; the output branch has a second transistor, and 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, and the control end of the third transistor is directly or indirectly connected to the output end of the second transistor.

[0006] 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 end of the second transistor includes the electrical performance information μ o C ox . When this voltage is used to control the third transistor, it will cancel out the device electrical performance information μ o C ox of the third transistor. Therefore, within the linear operating range, the degree of turn-on of the third transistor and the voltage at the output end of the second transistor exhibit a more accurate linear relationship, and there is no additional attenuation slope error introduced due to the different values of μ o C ox at different temperatures, achieving temperature compensation for the attenuation slope.

[0007] In some embodiments, 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 respectively connected to the external voltage interface and the output end of the first transistor, and is configured to clamp the voltage value at the output end of the first transistor to the voltage value of the external voltage interface.

[0008] 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, avoiding transmission loss and further reducing the fluctuation of the attenuation slope.

[0009] 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 at 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.

[0010] In this way, the voltage regulation circuit regulates the voltage value at the output end of the second transistor to the linear operating range corresponding to the attenuation branch, thereby driving the attenuation branch to operate and accurately regulating its attenuation amount.

[0011] In some embodiments, the resistance value of the first resistor is adjustable; and / or, the temperature coefficient of the first resistor is less than or equal to a preset value.

[0012] In this way, by calibrating the resistance value of the first resistor, the translation of the attenuation slope can be achieved, compensating for the simulation error of the threshold voltage of the transistor and further compensating for the attenuation slope error caused by temperature. Additionally, the influence of temperature on the resistance value of the first resistor is almost negligible, avoiding the introduction of additional errors.

[0013] In some embodiments, the first resistor includes a resistor array composed of multiple resistors.

[0014] In this way, the resistance value of the first resistor can be flexibly adjusted and the cost is not high.

[0015] In some embodiments, the analog branch includes an analog transistor, and the device type and aspect ratio of the analog transistor are the same as those of the third transistor; the control end of the analog transistor receives a fixed voltage, and the fixed voltage is greater than the threshold voltage of the analog transistor.

[0016] In this way, through the fixed voltage, the analog branch is in a fixed operating state, enabling the voltage at the output end of the second transistor to carry electrical performance information.

[0017] In a second aspect, embodiments of the present disclosure provide a radio frequency chip, which includes the voltage-controlled attenuator as described in the first aspect.

[0018] For this radio frequency chip, the error of the attenuation slope of the voltage-controlled attenuator therein is small and it has a stable port standing wave. Description of the Drawings

[0019] Figure 1 Schematic diagram of the position of the signal attenuation circuit provided by the embodiments of the present disclosure; Figure 2 Schematic diagram of the structure of the signal attenuation circuit provided by the embodiments of the present disclosure; Figure 3 Schematic diagram of the change of the equivalent resistance of a transistor with the gate voltage; Figure 4 Equivalent schematic diagram of the signal attenuation circuit provided by the embodiments of the present disclosure; Figure 5 Schematic diagram of the structure of Example 1 of the first voltage-controlled attenuator provided by the embodiments of the present disclosure; Figure 6 Detailed schematic diagram of the structure of Example 2 of the first voltage-controlled attenuator provided by the embodiments of the present disclosure; Figure 7 Schematic diagram of the structure of the second voltage-controlled attenuator provided by the embodiments of the present disclosure; Figure 8 Schematic diagram of the structure of the third voltage-controlled attenuator provided by the embodiments of the present disclosure; Figure 9 Schematic diagrams of several current mirror structures provided by the embodiments of the present disclosure; Figure 10 Schematic diagram of the application scenario of the first voltage-controlled attenuator provided by the embodiments of the present disclosure; Figure 11 Schematic diagram of the structure of the second control circuit provided by the embodiments of the present disclosure; Figure 12 Schematic diagram of the simulation results of a voltage-controlled attenuator provided by the embodiments of the present disclosure Figure 1 ; Figure 13 Schematic diagram of the simulation results of a voltage-controlled attenuator provided by the embodiments of the present disclosure Figure 2 ; Figure 14 Schematic diagram of the composition structure of a radio frequency chip provided by the embodiments of the present disclosure. Detailed implementation manners

[0020] Next, the technical solutions in the embodiments of the present disclosure will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present disclosure. It can be understood that the specific embodiments described herein are only used to explain the related application, rather than limiting the application. In addition, it should be noted that for the sake of description, only the parts related to the related application are shown in the drawings. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present disclosure belongs. The terms used herein are only for the purpose of describing the embodiments of the present disclosure and are not intended to limit the present disclosure. In the following description, reference is made to "some embodiments", which describe a subset of all possible embodiments. However, it can be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments, and can be combined with each other without conflict. It should be pointed out that the terms "first / second / third" involved in the embodiments of the present disclosure are only used to distinguish similar objects and do not represent a specific order for the objects. It can be understood that "first / second / third" can be interchanged with a specific order or sequence when permitted, so that the embodiments of the present disclosure described herein can be implemented in an order other than the illustrated or described order.

[0021] A voltage-controlled attenuator is a common component in a radio frequency link, and its main function is to adjust the intensity of a radio frequency signal. The core of the voltage-controlled attenuator is a signal attenuation circuit. Please refer to Figure 1 , which shows a schematic diagram of the position of the signal attenuation circuit 20 in the radio frequency link. As Figure 1 shown, the signal attenuation circuit 20 is connected in series between the first radio frequency module 11 and the second radio frequency module 12 and is generally a passive device. The signal attenuation circuit 20 has various structures, such as a T-shaped network, a π-shaped network, a bridge T-shaped network, etc.

[0022] Taking the T-shaped network as an example, please refer to Figure 2, which shows a schematic structural diagram of a signal attenuation circuit 20 employing a T-shaped network. As Figure 2 shown, the signal attenuation circuit 20 includes a transmission main path and an attenuation branch presenting a T-shaped arrangement. The transmission main path includes transistors M1 and M2 connected in series, and the attenuation branch includes transistor M3. The input end of transistor M1 serves as a radio frequency input end RFin to receive a radio frequency signal, and the output end of transistor M2 serves as a radio frequency output end RFout to output a radio frequency signal; the input end of transistor M3 is connected to the output end of transistor M1, and the output end of transistor M3 is connected to the standard ground. In this way, the radio frequency signal is transmitted via the transmission main path, and part of the signal is transmitted to the ground via the attenuation branch, realizing the attenuation function.

[0023] In terms of control, the control end of transistor M3 receives a main control voltage Vctrl, which is generally externally input. The control ends of transistors M1 and M2 receive a feedback control voltage Vtune. Overall, transistor M3 can be equivalent to a variable resistor, whose resistance value changes with the voltage of the main control voltage Vctrl. Transistors M1 and 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-shaped attenuation circuit works. The voltage value of the main control voltage Vctrl is usually continuous, so the impedance of the attenuation branch changes continuously, thus it 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 the impedance matching between the voltage-controlled attenuator and the front and rear radio frequency devices, so as to ensure the best standing wave characteristics.

[0024] Please refer to Figure 3 , which shows a schematic diagram of the change of the equivalent resistance of a transistor with the gate voltage. In Figure 3 , its horizontal axis (X-axis) is the gate voltage Vg, and its vertical axis (Y-axis) is the equivalent resistance. When the gate voltage Vg increases, the equivalent resistance of the transistor will gradually decrease. For the part enclosed by the dotted line, the change of the equivalent resistance of transistor M3 with the gate voltage approximately shows a linear relationship. That is to say, by limiting the voltage range of the main control voltage Vctrl, the resistance value of transistor M3 is kept linearly changing, so that the network attenuation amount has an approximate linear relationship with the voltage of the main control voltage.

[0025] Please refer to Figure 4 , which is a simplified schematic diagram of the signal attenuation circuit 20. The resistance value of transistor M3 As shown in formula (1), the attenuation amount of the signal attenuation circuit 20 As shown in formula (2), the attenuation slope of the signal attenuation circuit 20 As shown in formula (3).

[0026] ………………………… (1) Among them, refers to the aspect ratio of transistor M3, refers to the gate-source voltage difference of transistor M3, refers to 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.

[0027] ………………………… (2) ………………………… (3) It can be seen from formula (1) to formula (3) that the attenuation slope is related to the electrical performance information μ o C ox of transistor M3, and is also related to the overdrive voltage (V gs -V T ). In formula (3), RK is a simplified representation of the relationship of some parameters that are not of much concern, and can be specifically derived from formula (1) and formula (2). R refers to other resistors or line resistors in the circuit and can be regarded as a constant.

[0028] As an engineering product, it is desired that the attenuation slope is a fixed value within the operating voltage and temperature range. Therefore, it is very meaningful from an engineering perspective to implement a linear voltage-controlled attenuator with low attenuation slope error.

[0029] Therefore, the present disclosure aims to provide a voltage-controlled attenuator with low attenuation slope error, which has stable performance at different operating temperatures and has high significance from an engineering perspective.

[0030] The following will describe each embodiment of the present disclosure in detail with reference to the accompanying drawings.

[0031] In an embodiment of the present disclosure, refer to Figure 5 , which shows a schematic structural diagram of a voltage-controlled attenuator 200 provided by an embodiment of the present disclosure. As Figure 5 shown, the voltage-controlled attenuator 200 includes a signal attenuation circuit 20 and a first control circuit 21.

[0032] Please refer to Figure 5, for the signal attenuation circuit 20, it includes a transmission main path 201 and an attenuation branch 202. The transmission main path 201 is connected in the radio frequency link (i.e., between the radio frequency input port RFin and the radio frequency output port RFout), and the attenuation branch 202 is connected to the transmission main path 201; the signal attenuation circuit 20 is configured to attenuate the radio frequency signal in the transmission main path 201 via the attenuation branch 202. In this way, the transmission main path 201 in the voltage-controlled attenuator 200 is mainly used to transmit the radio frequency signal, and the attenuation branch 202 releases part of the energy to other places, thereby realizing the signal attenuation function. The working parameters of the attenuation branch 202 determine the attenuation amount of the radio frequency signal.

[0033] Please refer to Figure 5 , the first control circuit 21 includes a current mirror structure 212. The current mirror structure 212 has an input branch 212a and an output branch 212b, and 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 this 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, and the analog branch 33 has the same structure as the attenuation branch 202.

[0034] The attenuation branch 202 includes a third transistor 53, and the control end of the third transistor 53 is directly or indirectly connected to the output end N2 of the second transistor 32.

[0035] It should be understood that for a transistor, the control end refers to the gate, the input end refers to one of the drain and the source, the output end refers to the other of the source and the source, and the input end and the output end are allowed to be interchanged depending on the actual current flow direction.

[0036] It should be noted that for the signal attenuation circuit 20, the electrical performance information μ o C ox of the circuit devices will introduce different error values at different temperatures (μ oThe specific value of o C ox is affected by temperature), resulting in a non-linear attenuation slope. In the embodiments 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. 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 replication 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 through the analog branch 33, and the voltage V2 carries the electrical performance information μ of the devices in the analog branch 33 o C ox , specifically as shown in formula (5).

[0037] I2 = I1 = Vm / Rref …………………………………(4) V2 = I2 × Rds = ≈ ……………(5) Among them, 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 aspect 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 is much smaller than 2.5V.

[0038] In the embodiments of the present disclosure, the circuit structures of the analog branch 33 and the attenuation branch 202 are the same. Therefore, the electrical performance information of the third transistor 53 in the attenuation branch 202 is also μ o C ox , and the aspect ratio of the third transistor 53 is W3 / L3. Since the resistance value Rds2 of the third transistor 53 is affected by both the electrical performance information μ o C ox and the voltage V2 (the voltage V2 is directly or indirectly applied to the control terminal of the third transistor 53), the electrical performance information μ o C ox carried by the control terminal voltage V2 cancels out the electrical performance information μ o C ox of the devices in the attenuation branch 202, so that the resistance value Rds2 of the third transistor 53 is not affected by the electrical performance information μ o C ox . See formula (6). According to formula (6), the resistance value Rds2 of the third transistor 53 is only related to the resistance value Rref of the first resistor 34 and the voltage Vm of the external voltage interface, and is not related to μ o Cox is related, and will not introduce additional errors due to the electrical performance information μ o C ox varying at different temperatures, thereby compensating for the attenuation slope error caused by the electrical performance information of the device at different temperatures.

[0039] Rds2 = …………(6) wherein, Vth refers to the threshold voltage of the resistance value Rds2 of the third transistor 53.

[0040] The attenuation amount of the voltage-controlled attenuator 200 is as shown in formula (7). According to formula (7), since Rds2 has nothing to do with the electrical performance information μ o C ox is irrelevant, the attenuation amount has nothing to do with the electrical performance information μ o C ox is irrelevant, but is related to Vm and Rref. At the same time, for a specific voltage-controlled attenuator 200, Rref is shown as a fixed value. Therefore, the attenuation amount can be regarded as varying with Vm, and the attenuation slope will be shown as a fixed value.

[0041] …………………………(7) wherein, R is a constant, representing the resistance in the circuit or the resistance of the line itself.

[0042] It should be understood that the above formula inference is an ideal situation. Affected by actual devices and working environments, the attenuation slope will still fluctuate. However, the fluctuation of the attenuation slope of the voltage-controlled attenuator 200 provided by the present disclosure is significantly reduced. In this way, the performance of the voltage-controlled attenuator 200 provided by the embodiments of the present disclosure is more stable, and when applied to electronic devices, it will bring a more stable working state and better output performance to the electronic devices.

[0043] In some embodiments, the circuit device sizes of the analog branch 33 and the attenuation branch 202 are the same (within the allowable error range), so as to better cancel the electrical performance information of the device and reduce the attenuation slope error of the voltage-controlled attenuator 200.

[0044] Specifically, please refer to Figure 5 , the analog branch 33 includes an analog transistor 331, and the device type and width-to-length ratio of the analog transistor 331 are the same as those of 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.

[0045] The value of the fixed voltage is determined according to actual device parameters. For example, the fixed voltage Vs is 2.5V.

[0046] In some embodiments, 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.

[0047] In other embodiments, if there is an error when the voltage value Vm of the external voltage interface is directly transmitted to N1, the voltage received at N1 is not Vm. Therefore, refer to Figure 6 , the first control circuit 21 further includes a clamping circuit 211; the clamping circuit 211 is respectively connected to the external voltage interface and the output terminal N1 of the first transistor 31, and is configured to clamp the voltage value at the output terminal of the first transistor 31 to the voltage value Vm of the external voltage interface.

[0048] It should be noted that the clamping circuit 211 can be implemented by an operational amplifier.

[0049] Please refer to Figure 6 , the clamping circuit 211 includes a first operational amplifier 2111. The first input terminal of the first operational amplifier 2111 is connected to the external voltage interface, and the second input terminal of the first operational amplifier 2111 is connected to the output terminal N1 of the first transistor 31.

[0050] 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, and the function of voltage clamping is realized by means of feedback adjustment. In particular, since there may be multiple transistors in the input branch 212a, according to the different structures of the input branch 212a, the first operational amplifier 2111 may need to be connected to the output terminals of different transistors.

[0051] In a specific embodiment, as Figure 6 shown, the current mirror structure 212 includes a first transistor 31 and a second transistor 32; the input terminal of the first transistor 31 receives the power supply voltage VDD, and the input terminal of the second transistor 32 receives the power supply voltage VDD; the control terminals of the first transistor 31 and the second transistor 32 are connected.

[0052] At this time, the output terminal of the first operational amplifier 2111 is connected to the control terminal of the first transistor 31.

[0053] In addition, the clamping circuit 211 can also be implemented by structures such as diodes, capacitors, resistors, or a dedicated clamping IC (Clamping IC), etc.

[0054] In another specific embodiment, as Figure 7As 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 ends of the first transistor 31 and the second transistor 32 both receive the power supply voltage VDD, and the control end of the first transistor 31, the output end of the first transistor 31, the control end of the second transistor 32, and the input end of the fourth transistor 35 are connected. At this time, the output end of the first operational amplifier 2111 is connected to the control end of the fourth transistor 35, and the fourth transistor 35 is connected to the first resistor 34. The driving end of the first operational amplifier receives the power supply signal VDD.

[0055] For Figure 7 , the first resistor 34 is indirectly connected to the output end of the first transistor 31.

[0056] In another specific embodiment, as Figure 8 shown, the current mirror structure 212 includes a first transistor 31, a second transistor 32, and a fourth transistor 35. The control ends of the first transistor 31 and the second transistor 32 are connected, the output end of the first transistor 31 and the input end of the fourth transistor 35 are connected, the control end and the output end of the fourth transistor 35 are connected, 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.

[0057] In the above embodiment, both the first transistor 31 and the second transistor 32 are PMOS. Figure 9 Several other current mirrors composed of PMOS are also shown (not all). In addition, NMOS can also be used to form a current mirror, and its specific structure needs to match the selected transistor type.

[0058] As can be seen from the above, there are various types of current mirror structures 212, and the specific connection method of the clamping circuit 211 can be matched with the current mirror structure 212.

[0059] In some embodiments, please refer to Figure 6 , the first control circuit 21 further includes a voltage regulation circuit 213. The voltage regulation circuit 213 is connected to the output end N2 of the second transistor 32 and is configured to regulate the voltage at the output end 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 the main control voltage Vctrl. The control end of the third transistor 53 receives the main control voltage Vctrl.

[0060] In one example, the voltage regulation circuit 213 can amplify / attenuate the voltage V2 at N2 to obtain the main control voltage Vctrl. Thus, within a preset voltage range, the voltage value of the main control voltage Vctrl has a multiple relationship with the voltage V2 at N2, completely canceling out the electrical performance information μ of the devices in the attenuation branch 202. o C ox , and the attenuation slope fluctuation of the voltage-controlled attenuator 200 is small.

[0061] In this example, please refer to 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, the first terminal of the third resistor 43, and the second input terminal of the second operational amplifier 41 are connected; 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.

[0062] In another example, the voltage regulation circuit 213 can include a diode chain, using the forward voltage drop of the diode (generally 0.7V for silicon diodes and 0.3V for germanium diodes) to achieve voltage elevation or reduction, so that the obtained main control voltage Vctrl is within the linear working range of the voltage-controlled attenuator and at the same time carries the electrical performance information μ. o C ox .

[0063] Please refer to Figure 12 , which shows the attenuation slope change schematic diagrams of a traditional voltage-controlled attenuator (without the first control circuit 21, and 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 (for reference Figure 6 ) at three different temperatures. Specifically, curves a1, b1, and c1 are the schematic diagrams of the attenuation slope of the traditional voltage-controlled attenuator varying with the external voltage interface Vm at 85°C, 25°C, and -40°C respectively; curves a2, b2, and c2 are the schematic diagrams of the attenuation slope of the voltage-controlled attenuator 200 provided by the present disclosure varying with the external voltage interface Vm at 85°C, 25°C, and -40°C respectively.

[0064] As Figure 12As shown, when the voltage Vm at 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 to say, when the voltage Vm at the external voltage interface remains unchanged, when the temperature changes, the change amplitude of the attenuation slope of the traditional voltage-controlled attenuator is large, while the change amplitude of the attenuation slope of the voltage-controlled attenuator 200 of the present disclosure is small. That is, the attenuation slope fluctuation of the voltage-controlled attenuator 200 of the present disclosure is less than the attenuation slope fluctuation of the traditional voltage-controlled attenuator. As Figure 12 shown, for the highest point of curve a1, the attenuation slope is about -1.7; for the lowest point of curve c1, the attenuation slope is about -6.3; thus, the attenuation slope fluctuation of the traditional voltage-controlled attenuator is approximately 4.5. When Vm = 700 mV, for the highest point of curve a2, the attenuation slope is about -3.5; for the lowest point of curve c2, the attenuation slope is about -5.1; thus, the attenuation slope fluctuation of the voltage-controlled attenuator 200 of the present disclosure is approximately 1.5.

[0065] In some embodiments, please refer to Figure 6 , the resistance value of the first resistor 34 is adjustable. In this way, the current I1 at N1 is adjustable, so that the current I2 at the replicated second node is adjustable, and the resistance value of the equivalent resistance Rds2 of the third transistor 53 is adjustable. Refer to the foregoing formula (6).

[0066] The attenuation amount of the voltage-controlled attenuator 200 is related to the equivalent resistance Rds2 of the third transistor 53. Therefore, when the main control voltage Vctrl remains unchanged, by adjusting the resistance value of the first resistor 34, the attenuation amount can be changed, the specific value of the attenuation slope can be adjusted, and the simulation error of the threshold voltage of the transistor can also be compensated, further compensating the attenuation slope error caused by temperature and the device batch error. Here, the resistance value of the first resistor 34 is also allowed to be adjusted after leaving the factory.

[0067] Please refer to 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 values of the first resistor are 1.1R0, 1.05R0, R0, 0.95R0, and 0.9R0 respectively. R0 is a fixed value, Figure 13 and the ambient temperature is fixed at room temperature. It can be seen that when the voltage Vm at the external voltage interface is fixed, 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 value of 1.1R0), curve e (using the first resistor 34 with a resistance value of 0.9R0) is approximately translated downward by about 0.5 to 1.

[0068] In this way, on the one hand, the embodiments of the present disclosure reduce the fluctuation of the attenuation slope by offsetting the device electrical performance information μ o C ox so that the attenuation slopes at various temperatures tend to be consistent; on the other hand, the translation of the attenuation curve can also be achieved by adjusting the resistance value of the first resistor 34, where the resistance value of the first resistor 34 can be adjusted after the chip production to make up for the differences in process batches.

[0069] In a specific example, the first resistor 34 includes a resistor array composed of multiple resistors, so as to achieve adjustable resistance values.

[0070] 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 problems caused by the device process error.

[0071] In yet another specific example, the first resistor 34 includes a resistor array composed of multiple low-temperature coefficient resistors, which not only achieves adjustable resistance values, but also the resistance value of the first resistor 34 is little affected by temperature, avoiding the introduction of additional errors.

[0072] In some embodiments, the signal attenuation circuit 20 adopts a T-type network. Please refer to 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 ends of the fifth transistor 51 and the sixth transistor 52 both receive the feedback control voltage Vtune.

[0073] In some other embodiments, the signal attenuation circuit 20 can also adopt a π-type network. Since the π-type network has two symmetric attenuation branches, it is only necessary that the analog branch 33 has the same structure and device size as one of the attenuation branches. In addition, the signal attenuation circuit 20 can also adopt an L-type network, a bridge T-type network, etc.

[0074] Please refer to Figure 10, the voltage-controlled attenuator 200 further includes a second control circuit 22. The input end of the second control circuit 22 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 inverse dynamic relationship with the main control voltage Vctrl, so that the signal attenuation circuit 20 is impedance-matched with the RF modules before and after, ensuring the stability of the standing wave. Here, impedance matching means that the equivalent impedance of the RFin end of the signal attenuation circuit 20 is matched with the equivalent impedance of the output end of the first RF module 11, and the equivalent impedance of the RFout end of the signal attenuation circuit 20 is matched with the equivalent impedance of the input end of the second RF module 12.

[0075] In some embodiments, please refer to Figure 11 , the second control circuit 22 includes: a mirror attenuation circuit 221, which has the same circuit structure as the signal attenuation circuit 20. The mirror attenuation circuit 221 is directly or indirectly connected to the output end of the second transistor 32 (receiving the main control signal Vctrl), and the mirror attenuation circuit 221 is also connected to the output end of the second control circuit 22 (receiving the feedback control voltage Vtune for feedback regulation), so that the mirror attenuation circuit 221 has the same working state as the signal attenuation circuit 20; a second current mirror 222, which has an input branch and an output branch, and 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 end N3 of the seventh transistor 61 is connected to the ground via a sequentially connected mirror attenuation circuit 221 and a first load 71, and the output end N4 of the eighth transistor 62 is connected to the ground via a second adjustable load 72; the control end of the seventh transistor 61, the output end of the seventh transistor 61, and the control end of the eighth transistor 62 are connected, and the input ends of the seventh transistor 61 and the eighth transistor 62 both receive the power supply voltage VDD; a third current mirror 223, which has an input branch and an output branch, and 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 end N5 of the ninth transistor 63 is connected to the ground via a third load 73, and the output end N6 of the tenth transistor 64 is connected to the ground via a fourth adjustable load 74; the control end of the ninth transistor 63, the output end of the ninth transistor 63, and the control end of the tenth transistor 64 are connected, and the input ends of the ninth transistor 63 and the tenth transistor 64 both receive the power supply voltage VDD; A 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, and generate a feedback control voltage Vtune.

[0076] Here, the resistance values of the first load 71 and the third load 73 are the same. Since the inter-stage matching impedance in the RF field is generally 50 Ω, the resistance values of the first load 71 and the third load 73 can be taken as 50 Ω. The second adjustable load 72 and the fourth adjustable load 74 have the same structure. Exemplarily, each of the second adjustable load 72 and the fourth adjustable load 74 includes a transistor and a diode connected in series (or composed of multiple diodes connected in series).

[0077] In addition, the second control circuit can also be implemented by a similar circuit structure without being limited to the above circuit.

[0078] 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 actually may include one or more independent transistor devices. For example, the first transistor may include multiple transistor devices connected in series and / or multiple transistor devices connected in parallel, and may even include resistors. As long as the overall formed device has working characteristics similar to those of a transistor, it can be considered as the first transistor. The same applies to other transistor concepts. In addition, the first resistor to the third resistor may each include multiple resistor devices connected in series and / or in parallel.

[0079] In another embodiment of the present disclosure, refer to Figure 14 , which shows a schematic diagram of the composition structure of a radio frequency chip 80 provided by an embodiment of the present disclosure. As Figure 14 shown, the radio frequency chip 80 at least includes the aforementioned voltage-controlled attenuator 200.

[0080] The above are only the preferred embodiments of the present disclosure and are not intended to limit the protection scope of the present disclosure. It should be noted that in the present disclosure, the terms "including", "comprising" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device including a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the element. The serial numbers of the above embodiments of the present disclosure are only for description and do not represent the advantages or disadvantages of the embodiments. The methods disclosed in several method embodiments provided by the present disclosure can be arbitrarily combined without conflict to obtain new method embodiments. The features disclosed in several product embodiments provided by the present disclosure can be arbitrarily combined without conflict to obtain new product embodiments. The features disclosed in several method or device embodiments provided by the present disclosure can be arbitrarily combined without conflict to obtain new method embodiments or device embodiments. The above are only the specific implementation manners of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present disclosure can easily think of changes or substitutions, which should all be covered within 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 is connected in a radio frequency link, and the attenuation branch is 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; The first control circuit comprises: a current mirror structure; the current mirror structure has an input branch and an output branch, the output branch replicates the current of the input branch; the input branch has 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 has 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, and a control terminal of the third transistor is directly or indirectly connected to an output terminal of the second transistor.

2. The voltage-controlled attenuator according to claim 1, characterized in that: 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, characterized in that: The first control circuit further includes: a voltage regulating circuit; the voltage regulating 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 terminal of the third transistor receives the main control voltage.

4. The voltage-controlled attenuator according to any one of claims 1 to 3, characterized in that: The resistance value 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, characterized in that: The first resistor includes a resistor array composed of a plurality of resistors.

6. The voltage-controlled attenuator according to any one of claims 1 to 3, characterized in that: The analog branch includes an analog transistor, and the analog transistor and the third transistor have the same device type and width-to-length ratio; The control terminal of the analog transistor receives a fixed voltage, and the fixed voltage is greater than a threshold voltage of the analog transistor.

7. The voltage-controlled attenuator according to claim 2, characterized in that: The clamp circuit comprises 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, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: The transmission trunk includes a fifth transistor and a sixth transistor connected in series, the connection point between the fifth transistor and the sixth transistor is also connected to the input end of the third transistor, and the output end of the third transistor is connected to the standard ground; the control end of the fifth transistor and the control end 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 at 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 1-11.

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