阅读说明：本技术 一种基于非线性传输线的超宽带微波取样电路及取样方法 (Ultra-wideband microwave sampling circuit and sampling method based on nonlinear transmission line ) 是由 张士斌 徐从玉 范国清 代秀 解本琦 朱伟峰 于 2019-11-22 设计创作，主要内容包括：本发明公开了一种基于非线性传输线的超宽带微波取样电路及取样方法,该取样电路包括依次连接的自偏置非线性传输线窄脉冲发生电路、槽线-微带巴伦、取样门管电路和中频电路,本振信号进入自偏置非线性传输线窄脉冲发生电路后,产生一系列窄脉冲本振信号,通过槽线-微带巴伦转换成一对等幅反相的取样脉冲,在取样门管电路上对射频信号进行取样,经中频电路整形后输出,从而完成对射频信号的取样,本发明所公开的取样电路及取样方法可实现从射频频率到毫米波频率的超宽带频率覆盖；无需外加偏置电压,自偏置电路的设计简单、易实现,易调节、拓展性强且成本低。(The invention discloses an ultra-wideband microwave sampling circuit and a sampling method based on a nonlinear transmission line, wherein the sampling circuit comprises a self-biased nonlinear transmission line narrow pulse generating circuit, a slot line-microstrip balun, a sampling gate tube circuit and an intermediate frequency circuit which are connected in sequence, a series of narrow pulse local oscillator signals are generated after the local oscillator signals enter the self-biased nonlinear transmission line narrow pulse generating circuit, the narrow pulse local oscillator signals are converted into a pair of sampling pulses with equal amplitude and opposite phase through the slot line-microstrip balun, the radio frequency signals are sampled on the sampling gate tube circuit and output after being shaped by the intermediate frequency circuit, so that the sampling of the radio frequency signals is completed, and the sampling circuit and the sampling method can realize ultra-wideband frequency coverage from the radio frequency to the millimeter wave frequency; the self-bias circuit has the advantages of no need of external bias voltage, simple design, easy realization, easy adjustment, strong expansibility and low cost.)

1. An ultra-wideband microwave sampling circuit based on a nonlinear transmission line is characterized by comprising a self-biased nonlinear transmission line narrow pulse generating circuit, a slot line-microstrip balun, a sampling gate tube circuit and an intermediate frequency circuit which are sequentially connected.

2. The ultra-wideband microwave sampling circuit based on nonlinear transmission line according to claim 1, characterized in that the self-biased nonlinear transmission line narrow pulse generating circuit comprises a self-biasing circuit and a nonlinear transmission line circuit.

3. The ultra-wideband microwave sampling circuit based on nonlinear transmission line of claim 2, wherein the self-bias circuit comprises an inductor, a resistor and a capacitor.

4. The ultra-wideband microwave sampling circuit based on the nonlinear transmission line according to claim 2, wherein the nonlinear transmission line circuit comprises a high-impedance transmission line and a varactor schottky diode periodically loaded thereon, the high-impedance transmission line adopts a coplanar line structure, and the coplanar line and the varactor schottky diode are fabricated on a semiconductor substrate.

5. The ultra-wideband microwave sampling circuit based on nonlinear transmission line of claim 4, characterized in that the semiconductor substrate is GaAs substrate or InP substrate.

6. The ultra-wideband microwave sampling circuit based on the nonlinear transmission line is characterized in that the sampling gate tube circuit is a double-tube balanced sampling structure and consists of two Schottky diodes which are integrated together.

7. The ultra-wideband microwave sampling circuit based on nonlinear transmission line according to claim 1, characterized in that the ultra-wideband microwave sampling circuit adopts coplanar waveguide as radio frequency signal transmission line, and the sampling gate tube circuit is installed between the coplanar waveguide central strip line and the grounding strip line.

8. A sampling method of ultra-wideband microwave based on nonlinear transmission line is characterized in that after a local oscillation signal enters a self-biased nonlinear transmission line narrow pulse generating circuit, a series of narrow pulse local oscillation signals are generated and converted into a pair of equal-amplitude and opposite-phase sampling pulses through a slot line-microstrip balun, a radio frequency signal is sampled on a sampling gate tube circuit and output after being shaped by an intermediate frequency circuit, and thus sampling of the radio frequency signal is completed.

9. The sampling method of claim 8, wherein the rf signal and the narrow pulse local oscillator signal are applied to the sampling gate transistor circuit at different phases, respectively, and the narrow pulse local oscillator signal is transmitted to the vicinity of the central strip line of the sampling gate transistor circuit to excite and turn on the two schottky diodes of the sampling gate transistor circuit, and when the narrow pulse local oscillator signal returns to the center from the edge ground resistor, the reflected pulse turns off the two schottky diodes of the sampling gate transistor circuit; when the sampling gate tube circuit is conducted and presents low impedance, the high-frequency radio frequency input signal is taken out.

Technical Field

The invention relates to a microwave sampling technology, in particular to an ultra-wideband microwave sampling circuit and a sampling method based on a nonlinear transmission line.

Background

Microwave signal sampling techniques have found wide application in measurement and test instruments such as sampling oscilloscopes, vector network analyzers, spectrum analyzers, ultra-wideband receivers, and the like. The sampling technology adopts the principle of sampling and holding, and mainly has the functions of completing frequency conversion, converting a microwave signal into an intermediate frequency signal with a lower frequency and simultaneously keeping amplitude information and phase information of the microwave signal from being lost. Sampling is a core factor influencing the main indexes of the upper limit working frequency, the whole machine dynamic range and the like of a testing instrument.

In the sampling technology, a narrow pulse signal is required to control a diode sampling bridge to perform sampling so as to realize down-conversion. In the current sampling technology, a step recovery diode is mainly used for generating narrow pulses and controlling a diode sampling bridge to realize down-conversion. The basic principle is that a local oscillation signal enters an SRD pulse generating circuit through a low-pass filter to generate a series of step pulse signals, the step pulse signals are added to a sampling gate tube circuit to sample radio frequency signals, and the radio frequency signals are shaped by an intermediate frequency circuit, amplified and output, so that sampling frequency conversion of the radio frequency signals is completed, as shown in figure 1. The prior art has the defects that the conversion time and the carrier service life of a step recovery diode are limited, the width of a narrow pulse generated by the step recovery diode is limited, only a narrow pulse with a rising edge of dozens of picoseconds can be generated, the working frequency of a sampling circuit can only reach about 20GHz, and the requirement of wider frequency band testing cannot be met. The bandwidth is narrow, the limitation is very large, and the use requirement of large bandwidth and high frequency band is difficult to realize.

With the rapid development of electronic technology, various measurement and test devices are continuously developed in the directions of high frequency and broadband, which puts higher requirements on the working bandwidth of the sampling technology, and the previous sampling technology can not meet the requirements of instruments.

Disclosure of Invention

In order to solve the technical problems, the invention provides an ultra-wideband microwave sampling circuit and a sampling method based on a nonlinear transmission line, so as to achieve the purposes of expanding the bandwidth of a sampling technology, improving the working frequency and meeting the frequency conversion requirement of a large-bandwidth high-frequency testing instrument.

In order to achieve the purpose, the technical scheme of the invention is as follows:

an ultra-wideband microwave sampling circuit based on a nonlinear transmission line comprises a self-biased nonlinear transmission line narrow pulse generating circuit, a slot line-microstrip balun, a sampling gate tube circuit and an intermediate frequency circuit which are connected in sequence.

In the above scheme, the self-biased nonlinear transmission line narrow pulse generating circuit includes a self-biasing circuit and a nonlinear transmission line circuit.

In the above scheme, the self-bias circuit includes an inductor, a resistor, and a capacitor.

In the above scheme, the nonlinear transmission line circuit includes a high-impedance transmission line and a varactor schottky diode periodically loaded thereon, the high-impedance transmission line has a coplanar line structure, and the coplanar line and the varactor schottky diode are fabricated on a semiconductor substrate.

In a further technical scheme, the semiconductor substrate is a GaAs substrate or an InP substrate.

In the scheme, the sampling gate tube circuit is a double-tube balance sampling structure and consists of two Schottky diodes which are integrated together.

In the scheme, the ultra-wideband microwave sampling circuit adopts the coplanar waveguide as a radio frequency signal transmission line, and the sampling gate tube circuit is arranged between the central strip line and the grounding strip line of the coplanar waveguide.

A sampling method of ultra-wideband microwave based on nonlinear transmission line is to generate a series of narrow pulse local oscillation signals after the local oscillation signals enter a narrow pulse generating circuit of self-biased nonlinear transmission line, convert the signals into a pair of equal-amplitude and opposite-phase sampling pulses through a slot line-microstrip balun, sample the radio frequency signals on a sampling gate tube circuit, and output the signals after being shaped by an intermediate frequency circuit, thereby completing the sampling of the radio frequency signals.

In a further technical scheme, a radio frequency signal and a narrow pulse local oscillation signal are respectively added to a sampling gate tube circuit in different phases, when the narrow pulse local oscillation signal is transmitted to the vicinity of a central strip line of the sampling gate tube circuit, two Schottky diodes of the sampling gate tube circuit are excited and opened, and when the narrow pulse local oscillation signal returns to the center from an edge grounding resistor, pulses are reflected to close the two Schottky diodes of the sampling gate tube circuit; when the sampling gate tube circuit is conducted and presents low impedance, the high-frequency radio frequency input signal is taken out.

According to the technical scheme, the ultra-wideband microwave sampling circuit and the sampling method based on the nonlinear transmission line provided by the invention adopt the self-biased nonlinear transmission line to generate the ultra-narrow pulse, the input end of the narrow pulse generating circuit of the nonlinear transmission line adopts the self-biased circuit consisting of the inductor, the resistor and the capacitor, the compression efficiency and the harmonic output power are improved, the working bandwidth is improved, the frequency conversion loss of sampling is reduced, the additional direct current bias is not needed, the circuit structure is simplified, the debugging is easy, and the cost is low; the picosecond-magnitude ultra-narrow pulse generator is realized by utilizing the self-biased nonlinear transmission line, two Schottky diodes of a sampling gate tube circuit are started to obtain two paths of intermediate frequency signals, and the intermediate frequency signals are rectified, so that ultra-wide band sampling based on the nonlinear transmission line is realized. Compared with a sampling technology based on a step recovery diode, the sampling circuit greatly expands the working bandwidth and can work to 100 GHz.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below.

FIG. 1 is a schematic diagram of a conventional SRD sampling scheme;

FIG. 2 is a flow chart of a method for sampling ultra-wideband microwaves based on nonlinear transmission lines according to an embodiment of the present invention;

fig. 3 is a circuit diagram of an ultra-wideband microwave sampling circuit based on a nonlinear transmission line according to an embodiment of the present invention.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

The invention provides an ultra-wideband microwave sampling circuit based on a nonlinear transmission line, which comprises a self-bias nonlinear transmission line narrow pulse generating circuit, a slot line-microstrip balun, a sampling gate tube circuit and an intermediate frequency circuit which are sequentially connected as shown in figures 2 and 3.

The self-biased nonlinear transmission line narrow pulse generating circuit is realized by adopting a monolithic microwave integrated circuit chip (MMIC). The self-bias nonlinear transmission line narrow pulse generating circuit comprises a self-bias circuit and a nonlinear transmission line circuit, wherein the nonlinear transmission line circuit comprises a high-impedance transmission line and a variable-capacitance Schottky diode periodically loaded on the high-impedance transmission line, the high-impedance transmission line adopts a coplanar line structure, the coplanar line and the variable-capacitance Schottky diode are manufactured on a semiconductor substrate with high electron mobility and low loss, and the semiconductor substrate is a GaAs substrate or an InP substrate.

The input end of the self-bias nonlinear transmission line narrow pulse generating circuit is a self-bias circuit consisting of an inductor, a resistor and a capacitor. The self-bias potential improves the signal edge compression efficiency and harmonic output power of the nonlinear transmission line, no additional direct current power supply bias is needed, the circuit structure is simplified, the debugging is easy, and the cost is low. The narrow pulse signal generated by the self-biased nonlinear transmission line narrow pulse generating circuit is converted into a pair of equal-amplitude and opposite-phase sampling pulses through the slot line-microstrip balun, and the sampling pulses are added to the sampling gate tube circuit.

The sampling gate tube circuit is a double-tube balance sampling structure and consists of two Schottky diodes which are integrated together. The radio frequency signal and the narrow pulse local oscillation signal are respectively added to a Schottky diode of the sampling gate tube circuit in different phases.

Because the coplanar waveguide has the characteristic of low-loss transmission in an extremely wide frequency range, the ultra-wideband microwave sampling circuit adopts the coplanar waveguide as a radio-frequency signal transmission line, and two Schottky diodes of a sampling gate tube circuit are arranged between a central strip line and a grounding strip line of the coplanar waveguide. The Schottky diode is controlled by the sampling pulse to play a role of a high-speed switch, ultra-wide band sampling is realized, and two paths of generated intermediate frequency signals are output through the intermediate frequency circuit. Compared with the sampling technology based on the SRD, the sampling circuit greatly expands the working bandwidth, and can work to 100 GHz.

In terms of phase distribution, narrow pulse local oscillation signals are distributed on the two Schottky diodes in the same phase, and radio frequency signals are distributed on the two Schottky diodes in the opposite phase, so that leakage is reduced due to the different phase distribution, and good isolation between local oscillation and radio frequency ports is provided. Because the sampling pulse is a symmetrical complementary pulse, the noise introduced by a sampling pulse source can be eliminated at the output end of the sampling gate tube circuit, so that the signal-to-noise ratio of the Schottky diode is improved.

The invention discloses an ultra-wideband microwave sampling method based on a nonlinear transmission line, which comprises the following steps:

after the local oscillation signal enters the self-biased nonlinear transmission line narrow pulse generating circuit, a series of narrow pulse local oscillation signals are generated and converted into a pair of equal-amplitude and opposite-phase sampling pulses through a slot line-microstrip balun, the radio frequency signal is sampled on a sampling gate tube circuit and output after being shaped by an intermediate frequency circuit, and therefore sampling of the radio frequency signal is completed.

The radio frequency signal and the narrow pulse local oscillation signal are respectively added on the two Schottky diodes in different phases, when the narrow pulse local oscillation signal is transmitted to the vicinity of the central strip line of the two Schottky diodes, the two Schottky diodes of the sampling gate tube circuit are excited and opened, and when the narrow pulse local oscillation signal returns to the center from the edge grounding resistor, the reflected pulse enables the two Schottky diodes of the sampling gate tube circuit to be closed; when the sampling gate tube circuit is conducted and presents low impedance, the high-frequency radio frequency input signal is taken out.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.