System for realizing voltage control attenuator based on radio frequency broadband PIN diode

Abstract

The invention relates to a system for realizing a voltage control attenuator based on a radio frequency broadband PIN diode, which comprises a first PIN diode, a second PIN diode, a first inductor, a second inductor, a first blocking capacitor and a second blocking capacitor, the first PIN diode and the second PIN diode are sequentially connected in series, one end of the first inductor is connected with the positive electrode of the first PIN diode, and the other end of the first inductor is connected with the negative electrode of the second PIN diode. The other end of the first inductor is connected with bias voltage input, one end of the second inductor is connected with the negative electrode of the second PIN diode, the other end of the second inductor is grounded, one end of the first blocking capacitor is connected with the positive electrode of the first PIN diode, and one end of the second blocking capacitor is connected with the negative electrode of the second PIN diode. According to the system for realizing the voltage control attenuator based on the radio frequency broadband PIN diode, the electrical modulation characteristic of the PIN diode is utilized, a microwave capacitor inductor is selected as a blocking bias device, the attenuator is simple in structure, short in response time and good in tracking performance, and the requirements of accuracy and stability can be met.

Description

Technical Field

[0001] The present invention relates to the field of radio frequency voltage-controlled attenuators, and in particular to the field of voltage-controlled attenuators, and specifically refers to a system for realizing a voltage-controlled attenuator based on a radio frequency broadband PIN diode. Background Art

[0002] As the current RF system has higher and higher requirements for the accuracy range of power control, voltage-controlled attenuators have gained more demand and applications as a supplement to digitally controlled attenuators.

[0003] The resistance of a PIN diode under radio frequency can be changed by changing the voltage applied to both ends of the diode. Its impedance is only related to the polarity and value of the voltage and has almost nothing to do with the amplitude of the microwave signal. Using this feature, the voltage across the PIN diode can be adjusted in the RF link to change the impedance of the PIN diode in the RF path and achieve precise attenuation of the link signal. In addition, PIN diodes have significant advantages in RF microwave circuits in terms of power resistance, low insertion loss, and extremely small parasitic electrical parameters. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a system for realizing a voltage-controlled attenuator based on a radio frequency broadband PIN diode, which has the characteristics of simple structure, high precision and wide application range.

[0005] In order to achieve the above object, the system of the present invention for realizing a voltage controlled attenuator based on a radio frequency broadband PIN diode is as follows:

[0006] The system for realizing a voltage-controlled attenuator based on a radio frequency broadband PIN diode has the following main features: the system comprises a first PIN diode, a second PIN diode, a first inductor, a second inductor, a first DC blocking capacitor and a second DC blocking capacitor; the first PIN diode and the second PIN diode are connected in series in sequence; one end of the first inductor is connected to the positive electrode of the first PIN diode, the other end of the first inductor is connected to a bias voltage input; one end of the second inductor is connected to the negative electrode of the second PIN diode, the other end of the second inductor is grounded; one end of the first DC blocking capacitor is connected to the positive electrode of the first PIN diode, the other end of the first DC blocking capacitor is connected to a radio frequency input signal RF_IN; one end of the second DC blocking capacitor is connected to the negative electrode of the second PIN diode, and the other end of the second DC blocking capacitor is connected to a radio frequency output signal RF_OUT.

[0007] Preferably, the system further comprises a DAC module, wherein the DAC module is connected to one end of the first inductor and is used to control the magnitude of the bias voltage.

[0008] Preferably, the system controls the resistance of the PIN diode by changing the bias voltage of the first inductor input.

[0009] Preferably, the system uses microwave high-Q-value DC-isolating capacitors and bias inductors.

[0010] The system of the present invention for realizing a voltage-controlled attenuator based on a radio frequency broadband PIN diode provides an electrical adjustment characteristic utilizing the PIN diode, and selects microwave capacitors and inductors as DC-isolating bias devices. The attenuator has a simple structure, a short response time, and good tracking performance, and can ensure the requirements of accuracy and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The circuit diagram of the system for realizing a voltage-controlled attenuator based on a radio frequency broadband PIN diode of the present invention is shown.

[0012] Figure 2 The figure is a schematic diagram showing the relationship between the PIN diode resistance and the bias current of the system for realizing a voltage-controlled attenuator based on a radio frequency broadband PIN diode according to the present invention. DETAILED DESCRIPTION

[0013] In order to more clearly describe the technical content of the present invention, further description is given below in conjunction with specific embodiments.

[0014] The system of the present invention for realizing a voltage-controlled attenuator based on a radio frequency broadband PIN diode comprises a first PIN diode, a second PIN diode, a first inductor, a second inductor, a first DC blocking capacitor and a second DC blocking capacitor. The first PIN diode and the second PIN diode are connected in series in sequence, one end of the first inductor is connected to the positive electrode of the first PIN diode, the other end of the first inductor is connected to the bias voltage input, one end of the second inductor is connected to the negative electrode of the second PIN diode, the other end of the second inductor is grounded, one end of the first DC blocking capacitor is connected to the positive electrode of the first PIN diode, the other end of the first DC blocking capacitor is connected to the radio frequency input signal RF_IN, one end of the second DC blocking capacitor is connected to the negative electrode of the second PIN diode, and the other end of the second DC blocking capacitor is connected to the radio frequency output signal RF_OUT.

[0015] As a preferred embodiment of the present invention, the system further includes a DAC module, and the DAC module is connected to one end of the first inductor and is used to control the magnitude of the bias voltage.

[0016] As a preferred embodiment of the present invention, the system controls the resistance of the PIN diode by changing the bias voltage input to the first inductor.

[0017] As a preferred embodiment of the present invention, the system adopts microwave high-Q-value DC-isolating capacitors and bias inductors.

[0018] In a specific embodiment of the present invention, the voltage controlled attenuator has important applications in various communication systems, and is mainly used to control the output power of a signal. Aiming at the device requirements for variable attenuation in a radio frequency link, the present invention uses a PIN diode to design a voltage controlled attenuator used as a radio frequency circuit, so as to achieve precise control of the attenuation in the radio frequency link.

[0019] from Figure 1 It can be seen that in the circuit design of this patent, two PIN diodes are connected in series in the RF link, and the bias voltage forms a current loop through the inductors on both sides, and then a DC blocking capacitor is added on the outside to isolate the bias voltage from the RF circuit to form an independent attenuation circuit.

[0020] Ordinary diodes are composed of PN junctions, while PIN diodes are formed by adding a low-doped intrinsic semiconductor film between P and N semiconductor materials to form a PIN structure. Because of the existence of the intrinsic layer, PIN diodes can be used not only in low-frequency circuits, but also in high-frequency fields. In addition, PIN diodes have higher linearity than equivalent GaAs MESFETs and are more suitable for attenuator design. The use of multiple PIN diodes can minimize signal distortion.

[0021] In actual attenuation circuit applications, the input frequency of the PIN diode is usually required to be much higher than its cutoff frequency (usually greater than 10 times the cutoff frequency). Only then can the PIN diode be better regarded as a current-controlled resistor with a very small parallel capacitance. At this time, the required resistance can be obtained by simply changing the DC current of the PIN diode. The relationship between the resistance value of the PIN diode and the bias current is shown in Figure 2 shown.

[0022] from Figure 2 It can be seen that the resistance of the PIN diode is close to a linear relationship with the bias current. In the attenuator design, by changing the forward bias voltage of the PIN diode input, such as Figure 1 As shown in the figure, the bias voltage input from L1 is changed to control the resistance of the PIN diode in the circuit. Taking 50 ohm impedance as an example, the calculation formula of attenuation and resistance in the link is shown in formula 1:

[0023]

[0024] In RF circuits, the maximum isolation depends on the capacitive reactance of the PIN diode. Compared with a single PIN diode design, such as Figure 1As shown, designing two cascaded PIN diodes in the link can increase its maximum isolation and provide a greater attenuation range.

[0025] Selecting microwave high-Q DC blocking capacitors and bias inductors can reduce the insertion loss of high and low frequency signals in broadband signal paths and provide reliable link gain control.

[0026] exist Figure 1 In the circuit, the DAC controls the bias voltage, which is added to the two PIN diodes D1 and D2 through L1, and then flows back to the ground through L2. The RF input signal RF_IN first passes through the DC blocking capacitor C1, passes through the attenuation link composed of D1 and D2, and then outputs the RF_OUT signal through C2, thus realizing the attenuation process controlled by the DAC. The variable attenuator composed of PIN diodes is simple and symmetrical, and is suitable for many broadband circuit applications.

[0027] The specific implementation scheme of this embodiment can refer to the relevant description in the above embodiment, which will not be repeated here.

[0028] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0029] It should be noted that, in the description of the present invention, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, the meaning of "plurality" refers to at least two.

[0030] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0031] The system of the present invention for realizing a voltage-controlled attenuator based on a radio frequency broadband PIN diode provides an electrical adjustment characteristic utilizing the PIN diode, and selects microwave capacitors and inductors as DC-isolating bias devices. The attenuator has a simple structure, a short response time, and good tracking performance, and can ensure the requirements of accuracy and stability.

[0032] In this specification, the present invention has been described with reference to specific embodiments thereof. However, it is apparent that various modifications and variations may be made without departing from the spirit and scope of the present invention. Therefore, the specification and drawings should be regarded as illustrative rather than restrictive.

Claims

1. A system for implementing a voltage-controlled attenuator based on a radio frequency broadband PIN diode, characterized in that: The system includes a first PIN diode, a second PIN diode, a first inductor, a second inductor, a first DC blocking capacitor and a second DC blocking capacitor. The first PIN diode and the second PIN diode are connected in series in sequence. One end of the first inductor is connected to the positive electrode of the first PIN diode, and the other end of the first inductor is connected to the bias voltage input. One end of the second inductor is connected to the negative electrode of the second PIN diode, and the other end of the second inductor is grounded. One end of the first DC blocking capacitor is connected to the positive electrode of the first PIN diode, and the other end of the first DC blocking capacitor is connected to the radio frequency input signal RF_IN. One end of the second DC blocking capacitor is connected to the negative electrode of the second PIN diode, and the other end of the second DC blocking capacitor is connected to the radio frequency output signal RF_OUT.

2. The system for implementing a voltage controlled attenuator based on a radio frequency broadband PIN diode according to claim 1, characterized in that: The system further comprises a DAC module, which is connected to one end of the first inductor and is used to control the magnitude of the bias voltage.

3. The system for implementing a voltage controlled attenuator based on a radio frequency broadband PIN diode according to claim 1, characterized in that: The system controls the resistance of the PIN diode by changing the bias voltage input to the first inductor.

4. The system for implementing a voltage controlled attenuator based on a radio frequency broadband PIN diode according to claim 1, characterized in that: The system adopts microwave high-Q value DC blocking capacitors and bias inductors.

Images