PL215407B1 - Measure system of the microwave generator phase hypes - Google Patents

Description

The subject of the invention is a system for measuring the phase noise of a microwave generator, intended for use in microwave metrology, in particular for assessing the quality of manufactured microwave generators of various types and for various microwave frequency bands.

A system for measuring the phase noise of microwave generators is known which includes a reference generator. The output of this generator is connected to the input of the phase detector. The second input of this detector is connected to the output of the measured generator. The detector output is connected to a low-pass filter, the output of which is led to the input of the low-noise amplifier. The input of this amplifier is routed to the spectrum analyzer.

A system for measuring the phase noise of microwave generators is known, which comprises only the generator under test, the output of which is connected directly to the input of the spectrum analyzer.

A system for measuring phase noise is known from the patent description PL 159 293, comprising a phase detector, the inputs of which are connected to the reference generator and to the tested generator. The phase detector output is connected to the input of the low-noise amplifier, the output of which is connected to an analog-to-digital converter. The second input of this converter is connected to the computer via a control bus. The transducer output is connected to the computer input via a data bus. The computer's output is connected to the monitor and to the amplifier's output via the control circuit.

Many systems for measuring the phase noise of microwave generators are known, but none of them is capable of measuring the phase noise of all possible types of microwave generators. The known solutions are characterized by low sensitivity of the circuits to phase noise, especially in the range of low frequencies (1Hz to 100 Hz), and low measurement dynamics. In the case of the measurement method that uses only the spectrum analyzer, the total amplitude and phase noise is measured, which does not provide information about the phase noise itself, which is the most important when assessing the quality of the tested generator.

The essence of the system according to the invention consists in the fact that the output of the tested generator is connected through the first ferrite insulator to the first collinear input of the magic circuit T, and the low-noise tunable reference source is connected to the second collinear input of the magic circuit T, through the second ferrite insulator. The first exit doors of the magic system T are connected via a phase shifter to the first microwave detector, and the second exit doors of the magic system T are connected directly to the second microwave detector. The outputs of both microwave detectors are connected respectively to the two inputs of a low-noise differential amplifier, the output of which is connected simultaneously to the input of the spectrum analyzer and the input of the low-noise pumping generator.

Preferably, the output of the comb spectrum generator has a selected harmonic that is contained within the narrow passband of the tunable filter.

It is preferred that the tunable reference source low noise is a low noise pumping generator connected in series via a low noise amplifier, a low noise comb spectrum generator, a first low noise microwave amplifier with tunable bandpass filter input.

Preferably, a second low noise microwave amplifier is connected between the first exit door of the magic system T and the phase shifter, while a third low noise microwave amplifier is connected between the second exit door of the magic system T and the microwave detector.

It is also advantageous that the spectrum analyzer is an analog-to-digital converter connected via a computer to the plotter.

The advantage of the system according to the invention is a high measurement sensitivity for low frequencies, in the range 1 Hz to 100 Hz, thanks to the use of a phase locked loop created by a combination of a low-noise differential amplifier with a low-noise pumping generator, and an additional advantage is the broadband 1 GHz to 60 GHz of the measurement system and its high dynamics thanks to the use of a low-noise pumping generator, operating in a phase-locked loop and connected to the input of a low-noise comb spectrum generator. The compact and compact structure of the system was obtained by the use of the magic T system with a microwave detector connected to it in one of the exit doors through a phase shifter and a second microwave detector connected directly to the other exit doors of the system

The use of ferrite insulators placed directly in front of the collinear inputs enables the attenuation of signals reflected from microwave detectors, which results in no negative impact of the reflected signals on the tested microwave generator and the reference source. The use of commonly known microwave components makes the system easy to reconstruct and adapt to work at much higher ranges of measurement frequencies, and the use of a reference source allows the measurement of various types of microwave generators without the need to rebuild the entire measurement system.

The subject of the invention in an exemplary embodiment is presented in the drawing, in which Fig. 1 shows a system for measuring the phase noise of a microwave generator, Fig. 2 - a system for measuring phase noise of a microwave generator equipped with low-noise microwave amplifiers, and Fig. 3 - a noise measurement system. phase microwave generator with computer analysis of the output signal.

P r z k ł a d 1

The phase noise measurement circuit of the microwave generator has the output of the tested generator, which is connected to the input of the first ferrite insulator IZ1, the output of which is connected to the first collinear input 1 of the magic circuit T MT. As a low-noise pumping generator GP, the YH1322-B18-D-STD generator by Greenray Industries is used, which operates at low frequencies of 10 MHz -100 MHz and is connected to the input of the low-noise HV amplifier, the output of which is fed to the input of the low-noise GG comb spectrum generator, a Picosecond LPN 7100 generator was used. The output of the low noise comb spectrum generator GG is connected to the input of the first low noise microwave amplifier WM1, the output of which is connected to the tunable bandpass filter FP. The output of the tunable bandpass filter FP is connected via the second ferrite insulator IZ2 to the second collinear input 2 of the magic circuit T MT. The first exit door 3 of the magic system T is connected via a phase shifter PF to the input of the first microwave detector DM1, and the second exit door 4 of the magic system T is connected directly to the input of the second microwave detector DM2. The outputs of the first and second microwave detectors DM1, DM2 are connected to the two inputs of the low noise differential amplifier WR. The output 5 of the low-noise differential amplifier WR is connected simultaneously to the input of the low-noise pumping generator GP, which connection forms a phase locked loop, and as a useful output for the measured signal is fed to the input of the spectrum analyzer AW. In addition, the low-noise pumping generator GP connected in series via the low-noise amplifier WN1, the low-noise comb spectrum generator GG, the first low-noise microwave amplifier WM1 with the input of the tunable bandpass filter FP, constitute a tunable low-noise ZR reference source.

P r z k ł a d 2

The phase noise measurement system of the microwave generator is made as in the first example, with the difference that between the first exit gate 3 of the magic system T MT and the phase shifter PF and the second low-noise microwave amplifier WM2 is connected, and between the second exit gate 4 of the magic system T MT and The microwave detector DM2 is connected to the third low-noise microwave amplifier WM3, which results in better control of the microwave detectors DM1 and DM2 in the range of their linear operation.

The phase noise measurement system of the microwave generator is made as in the first or second example, with the difference that the spectrum analyzer AW is an AC analog-to-digital converter connected via a PC with a PL plotter.

P r z k ł a d 3

List of symbols in the drawing:

BG - tested generator,

PF - phase shifter,

MT - T magic system,

GP - pumping generator,

WN - low noise amplifier,

GG - low noise comb spectrum generator,

WM1 - the first low-noise microwave amplifier,

WM2 - the second low-noise microwave amplifier,

WM3 - the third low-noise microwave amplifier,

PL 215 407 B1

IZ1 - the first ferrite insulator,

IZ2 - second ferrite insulator,

FP - tunable bandpass filter,

DM1 - the first microwave detector,

DM2 - second microwave detector,

WR - low noise differential amplifier,

AW - spectrum analyzer,

ZR - reference source,

AC - analog to digital converter,

PC - computer,

PL - plotter,

- first collinear ascent,

- second collinear input,

- first exit gate,

- second exit gate,

- differential amplifier output.

Claims (5)

1. A system for measuring phase noise of a microwave generator, characterized in that the output of the tested generator (BG) is connected through the first ferrite insulator (IZ1) to the first collinear input (1) of the magic system T (MT), and to the second collinear input (2 ) of the magic T (MT) circuit is connected, through a second ferrite insulator (IZ2), a low noise tunable reference source (ZR), the first output port (3) of the magic T (MT) circuit is connected via a phase shifter (PF) to the first the microwave detector (DM1), while the second exit gate (4) of the magic T (MT) system is connected directly to the second microwave detector (DM2), the outputs of the microwave detectors (DM1 and DM2) are connected to the two inputs of the low-noise differential amplifier ( WR), the output of which (5) is connected simultaneously to the input of the spectrum analyzer (AW) and the input of the low-noise pumping generator (GP). 2. The system according to claim The method of claim 1, characterized in that the output of the low noise comb spectrum generator (GG) has a selected harmonic that is comprised in a narrow passband of the tunable bandpass filter (FP). 3. The system according to p. The method of claim 1, characterized in that the tunable reference source (ZR) is a low noise pumping generator (GP) connected in series through a low noise amplifier (WN), a low noise comb spectrum generator (GG), a first low noise microwave amplifier (WM1) with an input of a tunable bandpass filter ( FP). 4. The system according to p. The method of claim 1, characterized in that a second low-noise microwave amplifier (WM2) is connected between the first exit gate (3) of the magic T (MT) and the phase shifter (PF), and between the second exit gate (4) of the magic T (MT) and the phase shifter (PF). microwave detector (DM2) is enabled third low noise microwave amplifier (WM3). 5. The system according to p. The method of claim 1, wherein the spectrum analyzer (AW) is an analog-to-digital (AC) converter connected via a computer (PC) to the plotter (PL).