Noise source excess noise ratio test system and test method thereof

Abstract

The invention relates to a noise source excess noise ratio test system and a test method thereof. The test system comprises a standard noise source, an attenuator, a coupler, a low-temperature amplifier, a tested noise source, a GM refrigerator, a noise coefficient analyzer, a temperature sensor and a temperature controller. According to the invention, a change of an output Y factor of a low-temperature microwave link in the power supply and non-power supply states of the tested noise source is measured by constructing a test system, an increment of an equivalent noise temperature of the low-temperature microwave link composed of the coupler and the low-temperature amplifier is calculated, and then the excess noise ratio of the noise source is determined. Compared with the prior art, by using the system and the method of the invention, adverse effects of physical switch switching on a test process and a test result during a traditional test are eliminated, and the system and the methodare stable in test system, high in test precision, easy and convenient to operate and the like.

Description

technical field [0001] The invention relates to the technical field of noise source testing, in particular to a noise source ultra-noise ratio testing system and a testing method thereof. Background technique [0002] Noise source and noise figure analyzer, as a standard instrument for measuring noise performance, is widely used in testing the noise figure of microwave devices such as low-temperature amplifiers, microwave components, and receiving front-ends. The accuracy of the noise source over noise ratio determines the test error of the noise figure test. Existing measurement of noise source super-noise ratio adopts microwave switch to switch back and forth between immersion in liquid nitrogen load, normal temperature load and the noise source under test, and determines the equivalent output noise temperature of the noise source by comparing with the standard temperature, thereby determining Super noise ratio. This method requires that the load and the noise source hav...

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Problems solved by technology

This method requires that the load and the noise source have the same microwave impedance in the broadband range when the switch is switched in different states, but this is difficult to achieve in general, especially when measuring a noise source with a large super-noise ratio. Its output port is not well matched to the 50Ω measurement system, the impact of mismatch at all levels is inevitable, the test system is complex and the measurement repeatability is low, and at the same time, it needs to inject liquid nitrogen, which has certain safety hazards. These factors will affect the noise source super-noise ratio The test accuracy will affect the

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