CN215768707U - VHF high-precision signal source generator - Google Patents

Abstract

The utility model discloses a VHF high-precision signal source generator, which relates to the technical field of signal sources and solves the technical problem of the stepping precision of a signal source. The utility model can realize stepping precision as high as 1HZ, high bandwidth and large gain, and has the characteristics of high precision, wide frequency range, stable frequency output, small volume, low power consumption and flexible and convenient control.

Description

VHF high-precision signal source generator

Technical Field

The utility model relates to the technical field of signal sources, in particular to a VHF high-precision signal source generator.

Background

Modern science and technology develops rapidly, and each field is different day by day. In the research, development, test and production process in the field of wireless communication, four general-purpose measuring instruments, namely a signal generator, a network analyzer, a spectrum analyzer and an oscilloscope, are widely used, wherein the signal generator is the head of the four general-purpose electronic measuring instruments. In fact, the signal generator is the most basic and popular electronic measuring instrument, and is widely applied to the fields of wireless communication, production, scientific research, national defense and scientific experiments.

The signal generator is also called a signal source, the output signal type of the signal generator can be a sine wave signal, a function signal, a pulse signal, an arbitrary waveform signal or a digital modulation signal, and the output signal can be a bipolar signal without bias voltage or a signal with bias voltage. The bipolar signal refers to the change 1 of the output signal up and down the ground reference point. The signal source is an electronic instrument capable of generating a large number of standard signals and user-defined signals and ensuring high accuracy, stability, repeatability and ease of operation. The waveform generator has the advantages of continuous phase transformation, frequency stability and the like, can simulate various complex signals, can dynamically and timely control frequency, amplitude, phase shift and waveform, can communicate with other instruments, and forms an automatic test system. The existing signal generator is usually designed into a limited number of steps according to requirements, namely a limited number of stepping values, the stepping interval is large, accurate stepping cannot be achieved, and the universality is not strong enough.

SUMMERY OF THE UTILITY MODEL

The technical problem to be solved by the utility model is to overcome the defects in the prior art, and the utility model aims to provide a VHF high-precision signal source generator with high stepping precision.

The technical scheme of the utility model is as follows: the utility model provides a VHF high accuracy signal source generator, is 1Hz ~ 150 MHz's signal generation module, cutoff frequency is 150 MHz's low pass filter module, attenuation range be 0dB ~ 31.5dB and step minimum 0.5 dB's attenuator module, program controlled amplifier module, digital analog conversion module, host system including the output frequency range, the signal that signal generation module produced passes through in proper order low pass filter module, attenuator module, program controlled amplifier module obtain output signal, host system connects respectively signal generation module, attenuator module, host system passes through digital analog conversion module connects program controlled amplifier module.

As a further improvement, the model of the signal generation module is AD9854, and the signal generation module is connected with the main control module in a serial connection mode.

Further, the low-pass filter module is a seven-order pair triangular filter.

Further, the model of the programmable amplifier module is VCA 821.

Further, the model of the digital-to-analog conversion module is DAC 7621.

Further, the attenuator module is of a type PE 4302.

Further, the model number of the master control module is MSP430F 5438A.

Further, the mobile terminal also comprises a touch screen connected with the main control module.

Further, the touch screen is a TFT screen.

Advantageous effects

Compared with the prior art, the utility model has the advantages that:

the utility model can realize stepping precision as high as 1HZ, high bandwidth and large gain, and has the characteristics of high precision, wide frequency range, stable frequency output, small volume, low power consumption and flexible and convenient control.

Drawings

FIG. 1 is a block diagram of the present invention;

FIG. 2 is a circuit diagram of a signal generation module according to the present invention;

FIG. 3 is a circuit diagram of a low pass filter module according to the present invention;

FIG. 4 is a circuit diagram of a power module of the present invention;

FIG. 5 is a circuit diagram of an attenuator module according to the present invention;

FIG. 6 is a circuit diagram of a programmable amplifier module according to the present invention;

FIG. 7 is a circuit diagram of a main control module according to the present invention;

fig. 8 is a circuit diagram of the digital-to-analog conversion module of the present invention.

Wherein: the system comprises a 1-signal generation module, a 2-low-pass filter module, a 3-attenuator module, a 4-program control amplifier module, a 5-digital-to-analog conversion module, a 6-main control module and a 7-touch screen.

Detailed Description

The utility model will be further described with reference to specific embodiments shown in the drawings.

Referring to fig. 1-8, a VHF high-precision signal source generator includes a signal generating module 1 with an output frequency range of 1 Hz-150 MHz, a low pass filter module 2 with a cutoff frequency of 150MHz, an attenuator module 3 with an attenuation range of 0 dB-31.5 dB and a minimum step of 0.5dB, a program-controlled amplifier module 4, a digital-to-analog conversion module 5, and a main control module 6, wherein signals generated by the signal generating module 1 sequentially pass through the low pass filter module 2, the attenuator module 3, and the program-controlled amplifier module 4 to obtain output signals, the main control module 6 is respectively connected with the signal generating module 1 and the attenuator module 3, and the main control module 6 is connected with the program-controlled amplifier module 4 through the digital-to-analog conversion module 5.

The model of the signal generating module 1 is AD9854, the signal generating module 1 is connected with the main control module 6 by a serial connection mode, as shown in fig. 2, the AD9854 digital frequency synthesizer is a highly integrated device, and adopts an advanced DDS technology and two internal high-speed and high-performance quadrature digital-to-analog converters to form a digital programmable I and Q synthesizing function. The AD9854 of the high speed DDS core provides a frequency resolution of 48 bits (1 muHz adjusted to a system clock resolution of 300 MHz), a clock signal up to 300MHz, and an output signal up to 150 MHz. The AD9854 is internally integrated with a 48-bit frequency accumulator, a 48-bit phase accumulator, a sine-cosine waveform table, two 12-bit high-speed and high-performance orthogonal DACs and a modulation and control circuit, and can complete multiple functions of frequency modulation, phase modulation, amplitude modulation, IQ orthogonal modulation and the like on a single chip. When an accurate reference frequency is input, the AD9854 generates a high stable sine and cosine output with programmable modulation of frequency, phase and amplitude.

The low-pass filter module 2 is a seven-order diagonal triangular filter, as shown in fig. 3, the diagonal triangular filter has the characteristics of large attenuation coefficient of cut-off frequency, small in-band fluctuation and good flatness, and realizes a better low-pass filtering effect with-3 dB cut-off frequency of 150 MHZ. Meanwhile, shaping and filtering are carried out on the preceding-stage signals, and coupling matching is carried out on the preceding-stage and the following-stage circuits, so that better transmission of system signals is realized.

The attenuator module 3 is of a type PE4302, and as shown in fig. 5, the PE4302 is a high linearity, 6-bit RF Digital Step Attenuator (DSA) including an attenuation range of 0dB to 31.5dB step by minimum 0.5 dB. The signal amplitude control of digital control is realized through data, clk and other ports.

The programmable amplifier module 4 is model VCA821, and as shown in fig. 6, VCA821 is a dc-coupled, dB linear, continuously variable voltage controlled gain amplifier. It provides a differential input and single ended conversion to change the gain down to 40 db from a nominal maximum gain by setting the high impedance gain control input of the gain resistor (Rg) and feedback Resistor (RF). The internal architecture of the VCA821 includes two input buffers and an output current feedback amplifier stage integrated with a multiplier core to provide a complete Variable Gain Amplifier (VGA) system that does not require external buffering. Two resistors are provided outside the maximum gain, providing flexibility in design. When the ± 5V power supply operates, the gain control voltage VCA821 adjusts the gain of the straight line in dB from the control voltage of 0V to + 2V. For example, at a maximum gain of 20dB, the VCA821 has 20 dB; when Vg is +2V, the Vg is less than-20 dB; the VCA821 can also provide ideal gain linearity when Vg is 0V. For a maximum gain of 20dB and a variation between the gain control input voltages +1V and +2V, the gain does not exceed a deviation of ± 0.3 dB.

The digital-to-analog conversion module 5 is in the type of DAC7621, as shown in fig. 8, the DAC7621 is a complete input shift register and DAC register of a 12-bit digital-to-analog converter (DAC), and a 12-bit DAC, an on-chip reference and a rail-to-rail output amplifier are adopted. The conversion from digital signals to analog signals is realized, and the generated analog voltage signals are output to the high-frequency amplification module to realize VCA.

The model of the main control module 6 is MSP430F5438A, the utility model also comprises a touch screen 7 connected with the main control module 6, the touch screen 7 is a TFT screen, as shown in FIG. 7, MSP430F5438A produced by TI company is adopted, the utility model has a mixed type single chip microcomputer with simplified instruction set and ultra-low power consumption, the I/O port is sufficient, and the configuration is flexible. The master control chip MSP430F5438A adopted by the system has strong processing capacity. Its kernel is a 16-bit RISC processor that can execute one instruction in one clock cycle. The device has the characteristics of low power consumption, rich peripheral ports, sufficient I/O ports, flexible configuration, working voltage range of 1.8V-3.6V, 48I/O ports, 16-Bit RISC architecture and high processing speed. The clock circuit is composed of a 12.000MHZ passive crystal oscillator, and the signal of the reset circuit is effective when the signal is designed to be at a high level. And the AD9854 and the MSP430F5438A adopt a serial connection mode, so that the I/O resource of the single chip microcomputer is saved, and the function expansion and the product upgrade of the system are facilitated.

The power supply module of the utility model provides stable positive and negative five-volt voltage signals required by the system, so that the signal transmission is stable and efficient. The power supply module adopts LM78M05 and LMZ14201 to respectively form a positive power supply circuit and a negative power supply circuit. LM78M05 is a three-port current positive fixed voltage regulator, and has the protection function of turning off when overcurrent and overheat occurs, the maximum value of output current is 500mA, the maximum value of input bias current is 3.2mA, and the maximum value of input voltage is 35V. LMZ14201 is an EF network with large output power with input voltage ranging from 6V to 42V, 6W, up to 1A of output current, and up to 90% EF network efficiency. The external circuit is simple, and the high available effectual heat that reduces the system production of operational environment temperature and the advantage of low output voltage ripple have still been had simultaneously, can realize positive negative output voltage's design through the design.

The utility model can realize stepping precision as high as 1HZ, high bandwidth and large gain, and has the characteristics of high precision, wide frequency range, stable frequency output, small volume, low power consumption and flexible and convenient control.

The above is only a preferred embodiment of the present invention, and it should be noted that it is obvious to those skilled in the art that several variations and modifications can be made without departing from the structure of the present invention, which will not affect the effect of the implementation of the present invention and the utility of the patent.

Claims (9)

1. The VHF high-precision signal source generator is characterized by comprising a signal generation module (1) with an output frequency range of 1Hz to 150MHz, a low-pass filter module (2) with a cut-off frequency of 150MHZ, an attenuator module (3) with an attenuation range of 0dB to 31.5dB and a minimum stepping of 0.5dB, a program-controlled amplifier module (4), a digital-to-analog conversion module (5) and a main control module (6), wherein signals generated by the signal generation module (1) sequentially pass through the low-pass filter module (2), the attenuator module (3) and the program-controlled amplifier module (4) to obtain output signals, the main control module (6) is respectively connected with the signal generation module (1) and the attenuator module (3), and the main control module (6) is connected with the program-controlled amplifier module (4) through the digital-to-analog conversion module (5).

2. The VHF high-precision signal source generator according to claim 1, characterized in that the signal generating module (1) is AD9854, and the signal generating module (1) is connected with the main control module (6) in a serial connection mode.

3. A VHF high-precision signal source generator according to claim 1, wherein the low-pass filter module (2) is a seven-order-pair triangular filter.

4. VHF high-precision signal source generator according to claim 1, characterized in that the programmable amplifier module (4) is of the type VCA 821.

5. The VHF high-precision signal source generator according to claim 1, wherein the digital-to-analog conversion module (5) is of type DAC 7621.

6. The VHF high-precision signal source generator according to claim 1, wherein the attenuator module (3) is of the type PE 4302.

7. The VHF high-precision signal source generator according to claim 1, wherein the master control module (6) is of model MSP430F 5438A.

8. A VHF high-precision signal source generator according to claim 1, comprising a touch screen (7) connected to the main control module (6).

9. The VHF high-precision signal source generator according to claim 8, wherein the touch screen (7) is a TFT screen.

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