AGC circuit device suitable for OFDM system

Abstract

An automatic gain control (AGC) circuit device suitable for an orthogonal frequency division multiplexing (OFDM) system adopts an integrated circuit structure and comprises a detection module, an attenuation module and an operational amplifier module, based on a feed-forward design principle, a radio frequency signal is input into the detection module while being input into the attenuation module, and analog voltage output by the detection module is input into the operational amplifier to be amplified and then is used for directly controlling gain of the attenuation module. The device is simple in circuit, high in stability, small in circuit size and large in dynamic range, and can be widely applied to an OFDM (Orthogonal Frequency Division Multiplexing) system.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of radio frequency circuit, especially relates to a AGC circuit suitable for OFDM system. BACKGROUND

[0002] The main purpose of AGC (Auto Gain Control) circuit is to make the output signal amplitude stable or change in a small range when the input signal is large.

[0003] OFDM (Orthogonal Frequency Division Multiplexing) technology is a kind of multicarrier modulation technology. The basic principle is to divide the wideband carrier into multiple small bandwidth orthogonal subcarriers, and disperse the data stream to be sent to multiple subcarriers, so that the signal rate of each subcarrier is greatly reduced, thereby improving the ability to resist multipath and fading.

[0004] OFDM is a multicarrier modulation technology. With the increase of the number of carriers, the peak-to-average ratio (PAPR) of the signal also increases synchronously, and the signal dynamic range is large, so the AGC circuit is required to output the radio frequency signal quickly and stably. At the same time, due to some miniaturization application scenarios, the AGC circuit is required to be small in size and suitable for OFDM system, so the design of the AGC circuit is required.

[0005] The existing AGC circuit is large in size, high in complexity and poor in stability, and is not widely used in OFDM system. SUMMARY

[0006] The present disclosure provides an AGC circuit suitable for OFDM system, which adopts an integrated circuit design scheme, adopts a feedforward analog AGC circuit, has simple structure, high stability, small PCB size and can be applied to OFDM system.

[0007] The AGC circuit suitable for OFDM system provided by the present disclosure comprises a detector, an attenuator and an operational amplifier, wherein,

[0008] The attenuation module is used for attenuating and outputting the input radio frequency signal.

[0009] The input radio frequency signal is input into the detection module at the same time, the analog voltage output by the detection module is input into the operational amplifier for amplification, and the voltage output by the operational amplifier is used for directly controlling the gain of the attenuation module.

[0010] Compared with the prior art, the AGC circuit has the advantages that: (1) for an OFDM signal with a high peak-to-average ratio, a stable voltage can be output after the AGC circuit; (2) the circuit is simple in design and small in size; and (3) the AGC circuit can be widely applied to OFDM systems. BRIEF DESCRIPTION OF DRAWINGS

[0011] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which like reference characters refer to like parts throughout the different views of the drawings.

[0012] Figure 1 The circuit structure diagram of the present disclosure is shown in the accompanying drawings.

[0013] Figure 2 The circuit structure design diagram according to the exemplary embodiment of the present disclosure is shown in the accompanying drawings. DETAILED DESCRIPTION

[0014] Preferred embodiments of the present disclosure will be described herein below with reference to the accompanying drawings. Although the preferred embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so as to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0015] The present disclosure provides an AGC circuit suitable for an OFDM system, a principle diagram of which is shown in the accompanying drawings. Figure 1 The AGC circuit adopts an integrated circuit structure and includes a detector, an attenuator and an operational amplifier, and adopts a feedforward design scheme, wherein the detector is a root mean square response power detector.

[0016] The circuit structure diagram according to the exemplary embodiment of the present disclosure is shown in the accompanying drawings. Figure 2

[0017] The AGC circuit adopts a feedforward mode, and after a radio frequency input signal enters the circuit, the radio frequency input signal passes through the detector. The detector preferably uses AD8362 (or AD8363), which is a root mean square response power detector and is independent of the waveform and modulation mode. The detector is suitable for an OFDM system and has a dynamic range greater than 65 dB.

[0018] After passing through the detector, the analog voltage output by the detector is input to the operational amplifier for amplification, and the output voltage of the operational amplifier directly controls the attenuator.

[0019] The attenuator preferably uses an HMC973 analog attenuator, and the radio frequency signal is output after passing through the attenuator.

[0020] The present circuit is simple in design, small in size and suitable for OFDM systems.​

[0021] Test results: using vivado software, the OFDM signal through the AGC circuit is collected; according to the test results, the OFDM signal output by the AGC circuit is stable after being collected by vivado.

[0022] Using an oscilloscope, the output voltage of the OFDM signal after the detection chip is collected; for OFDM signals with high peak-to-average ratio, the AGC circuit can output stable voltage. Therefore, the AGC circuit can be widely applied to OFDM systems.

[0023] The above technical solution is only an exemplary embodiment of the present application. For those skilled in the art, on the basis of the application method and principle disclosed in the present application, various types of improvements or modifications can be easily made, and the method described in the above specific embodiments is not limited to the present application. Therefore, the above-described method is only preferred and has no limiting meaning.

Claims

1. An AGC circuit arrangement for use in an OFDM system, characterized by The integrated circuit structure comprises a detection module, an attenuation module and an operational amplifier module, wherein: The attenuation module is used for attenuating and outputting the input radio frequency signal; The input radio frequency signal is input into the detection module, the analog voltage output by the detection module is input into the operational amplifier for amplification, and the voltage output by the operational amplifier is used for directly controlling the gain of the attenuation module.

2. The apparatus of claim 1, wherein, The detection module adopts a root mean square response power detector.

3. The apparatus of claim 1, wherein, The detection module selects a power detector with a dynamic range not less than 65dB.

4. The apparatus of claim 2 or 3, wherein, The detection module adopts an AD8362 or AD8363 detector.

5. The apparatus of claim 1, wherein, The attenuation module uses an HMC973 analog attenuator.

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