阅读说明：本技术 一种数字信号调制系统及方法 (Digital signal modulation system and method ) 是由 黄海滨 马辉 于 2020-04-20 设计创作，主要内容包括：本发明涉及隔离放大器技术领域,具体为一种数字信号调制系统及方法,其能够有效解决带传输信号干扰的问题,其包括发送端模块和接收端模块,其特征在于,所述发送端模块和所述接收端模块之间通过磁耦合电路,所述磁耦合电路包括线圈和磁传感器,所述发送端模块包括顺次连接的前置放大器/滤波电路、二进制调制开关、Delta-Sigma带通调制器、电流源开关组,所述接收端模块包括二进制解调开关,所述二进制解调开关连接低通滤波器或数字信号处理单元；同时,本发明提供了对应的方法。(The invention relates to the technical field of isolation amplifiers, in particular to a digital signal modulation system and a digital signal modulation method, which can effectively solve the problem of interference of signals with transmission and comprises a sending end module and a receiving end module, and is characterized in that a magnetic coupling circuit is arranged between the sending end module and the receiving end module and comprises a coil and a magnetic sensor, the sending end module comprises a preamplifier/filter circuit, a binary modulation switch, a Delta-Sigma band-pass modulator and a current source switch group which are sequentially connected, the receiving end module comprises a binary demodulation switch, and the binary demodulation switch is connected with a low-pass filter or a digital signal processing unit; meanwhile, the invention provides a corresponding method.)

1. A digital signal modulation system comprises a sending end module and a receiving end module, and is characterized in that a magnetic coupling circuit is arranged between the sending end module and the receiving end module, the magnetic coupling circuit comprises a coil and a magnetic sensor, the sending end module comprises a preamplifier/filter circuit, a binary modulation switch, a Delta-Sigma band-pass modulator and a current source switch group which are sequentially connected, the receiving end module comprises a binary demodulation switch, and the binary demodulation switch is connected with a low-pass filter or a digital signal processing unit.

2. A digital signal modulation method is characterized in that an analog signal to be transmitted is modulated by a binary modulation switch after passing through a preamplifier/filter circuit, the modulation signal is further modulated by a Delta-Sigma band-pass modulator, the central frequency of a passband of the Delta-Sigma band-pass modulator is consistent with the modulation frequency of binary modulation, a further modulated signal converts a voltage signal into a signal in a current form through a current source switch group, the current signal is sent to a receiving end module through a magnetic coupling circuit, the binary demodulation switch demodulates the signal, the demodulated signal is filtered by a low-pass filter to remove high-frequency noise, reduces low-frequency signals to be transmitted and outputs the signals to chip pins or is digitally filtered by a digital signal processing unit, and the digital waveform of an analog signal to be transmitted is directly output to complete analog-digital conversion.

Technical Field

The invention relates to the technical field of isolation amplifiers, in particular to a digital signal modulation system and a digital signal modulation method.

Background

In the field of chip applications, it often occurs that the chip is required to perform analog signal transmission between two voltage domains, which must be performed in different power supply systems, and is therefore called an isolation amplifier; if the analog signal needs to be transmitted and analog-digital converted, the analog signal is used as an isolated analog-digital converter.

As shown in fig. 1, a transmission path different from a normal coupling method is adopted between a transmitting end 101 and a receiving end 102 of a conventional isolation amplifier, and the transmission path is usually performed by an optical coupling 103, an electric field coupling 104, a magnetic coupling 105, and the like. Wherein, the optical coupling needs special semiconductor process and packaging, the cost is higher and the integration level is not high; the electric field coupling method is limited by the problem that the chip area is large, low-frequency signals cannot be conducted, but high-frequency signals are easily interfered.

The magnetic coupling has the advantages of high integration level, low chip cost and the like because the technology of integrating the magnetic sensor (such as a Hall device, a magnetoresistive device and the like) on the chip is mature and the area of the magnetic sensor is small. A conventional magnetic coupling circuit is shown in fig. 2 (the right half is a schematic diagram, and the left half is a top view of the chip), and includes a coil for generating a magnetic field and a magnetic sensor for sensing the magnetic field. Since the frequency range of magnetic field induction by conventional magnetic sensors (e.g., hall devices, magneto-resistive devices, etc.) covers from dc to high frequencies (tens of khz to several mhz), magnetic sensors are susceptible to interference from external magnetic fields in this frequency range. Meanwhile, the magnetic sensor itself also exists such as: large direct current zero drift (Hall device), large self thermal noise (magnetoresistive device) and the like. If direct coupling of analog signals is used, it is easy to cause interference of the signals to be transmitted.

Disclosure of Invention

In order to solve the problem that the signal to be transmitted is easily interfered when the existing magnetic coupling isolation amplifier is directly coupled by using an analog signal, the invention provides a digital signal modulation system which can effectively solve the problem of interference of a signal with transmission and simultaneously provides a corresponding method.

The technical scheme is as follows: a digital signal modulation system comprises a sending end module and a receiving end module, and is characterized in that a magnetic coupling circuit is arranged between the sending end module and the receiving end module, the magnetic coupling circuit comprises a coil and a magnetic sensor, the sending end module comprises a preamplifier/filter circuit, a binary modulation switch, a Delta-Sigma band-pass modulator and a current source switch group which are sequentially connected, the receiving end module comprises a binary demodulation switch, and the binary demodulation switch is connected with a low-pass filter or a digital signal processing unit.

A digital signal modulation method is characterized in that an analog signal to be transmitted is modulated by a binary modulation switch after passing through a preamplifier/filter circuit, the modulation signal is further modulated by a Delta-Sigma band-pass modulator, the central frequency of a passband of the Delta-Sigma band-pass modulator is consistent with the modulation frequency of binary modulation, a further modulated signal converts a voltage signal into a signal in a current form through a current source switch group, the current signal is sent to a receiving end module through a magnetic coupling circuit, the binary demodulation switch demodulates the signal, the demodulated signal is filtered by a low-pass filter to remove high-frequency noise, reduces low-frequency signals to be transmitted and outputs the signals to chip pins or is digitally filtered by a digital signal processing unit, and the digital waveform of an analog signal to be transmitted is directly output to complete analog-digital conversion.

After the invention is adopted, the sending end module and the receiving end module which are redesigned apply a digital modulation mode, thereby furthest inhibiting the influence of direct current null shift and thermal noise in magnetic coupling and the influence of noise and null shift on a chip such as a preamplifier/filter circuit, and finally obtaining the required signal.

Drawings

FIG. 1 is a schematic diagram of a prior art isolation amplifier;

FIG. 2 is a schematic diagram of a magnetic coupling circuit;

FIG. 3 is a schematic diagram of the system of the present invention;

fig. 4 is a schematic structural diagram of the hall device.

Detailed Description

Referring to fig. 3, a digital signal modulation system includes a transmitting end module and a receiving end module, a magnetic coupling circuit is arranged between the transmitting end module and the receiving end module, the magnetic coupling circuit includes a coil 305 and a magnetic sensor 306, the transmitting end module includes a preamplifier/filter circuit 301, a binary modulation switch 302, a Delta-Sigma band-pass modulator 303, and a current source switch group 304, which are connected in sequence, the receiving end module includes a second-level demodulation switch 307, and the second-level demodulation switch 307 is connected to a low-pass filter 308 or a digital signal processing unit 309.

A digital signal modulation method, after passing through a preamplifier/filter circuit 301, an analog signal 300 to be transmitted is subjected to binary modulation by a simple binary modulation switch 302, and a modulation signal is further modulated by a Delta-Sigma band-pass modulator 303, wherein the passband center frequency of the Delta-Sigma band-pass modulator 303 is consistent with the modulation frequency of the binary modulation; the signal passes through a current source switch block 304, and the voltage signal is converted into a signal in a current form; when the current flows through the coil 305 with a specific shape, specifically, the shapes of the coils corresponding to the hall device shown in fig. 4 are respectively square, hexagonal and octagonal, a corresponding magnetic field signal is formed; the modules complete the conversion from the signals to be transmitted to the magnetic field signals; the frequency domain characteristics of the magnetic field signal are shown at 310, the frequency to be transmitted is at the mid-frequency position, and the low and high frequencies are unwanted noise (shaded in 310).

In the receiving end, the signal output by the magnetic sensor 306 is demodulated by a simple binary demodulation switch 307, the frequency spectrum of which is shown as 311, it can be seen that the signal to be transmitted has been demodulated from the intermediate frequency part to the low frequency part, and the noise (shaded part) is concentrated in the intermediate frequency and high frequency parts; the signal passes through a low-pass filter 308 to filter out unnecessary medium-high frequency noise (a shaded part surrounded by a dotted line), and finally, a low-frequency signal 310 to be transmitted is restored and output to a chip pin; or in the isolated analog-to-digital converter, the digital signal processing unit 309 directly performs digital filtering on the digital signal output by the binary demodulation switch 307, and directly outputs the digital waveform 320 of the analog signal 300 to be transmitted, thereby completing analog-to-digital conversion.

Fig. 2 is a schematic diagram of a magnetic coupling device, in which 201 is a coil and 202 is a magnetic sensor.

The modulation method of the invention adopts a digital modulation mode, thereby furthest inhibiting the influence of direct current zero drift and thermal noise in magnetic coupling and other circuits on a chip, such as: the effects of noise and null drift in the preamplifier/filter circuit 301. The functional components are simple, such as the binary modulation switch 302 and the binary demodulation switch 307, and a path of clock coupling transmission, namely 312 in the figure, is added.