Frequency-discrimination type KID (kinetic inductance detector) phase noise measurement circuit system and measurement method

Abstract

The invention discloses a frequency-discrimination type KID (kinetic inductance detector) phase noise measurement circuit system and measurement method. The circuit system comprises a frequency synthesis source, a directional coupler, a KID readout circuit detector readout circuit module, a mixer module, a low-pass filter, a direct-current amplifier, a data acquisition card and a control computer.According to the frequency-discrimination type KID (kinetic inductance detector) phase noise measurement circuit system and measurement method of the invention, a single broadband double-balance mixer and an adjustable phase shifter are adopted as core components, and therefore, a phase noise measurement and calibration process is significantly simplified, and the accuracy of the measurement result of the method is higher than that of the measurement result of a conventional homodyne mixing phase noise measurement method; and the power electric level of the frequency synthesis source is reduced, and parasitic direct-current bias of intermediate frequency output is also significantly reduced, and the amount of data processing and hardware costs are decreased.

Description

technical field [0001] The invention relates to a circuit system and an operation method for measuring the phase noise of a superconducting KIDs detector, belonging to the field of terahertz / optical technology research. Background technique [0002] Superconducting dynamic inductance detectors (Kinetic Inductance Detectors, KIDs) are a new type of low-temperature high-sensitivity detectors, which can be used for target imaging observations from millimeter wave to terahertz, optical / ultraviolet, X-ray, and γ frequency bands. The core circuit of the KIDs detector is mainly composed of a photon signal receiver and a microwave resonator. According to the working principle of KIDs, when an external radio frequency signal irradiates the KIDs detector, the superconducting Cooper pair rupture occurs after the receiver receives photon energy. , will lead to changes in the dynamic resistance and dynamic inductance of the microwave resonator, thus causing changes in the characteristics...

AI Technical Summary

Problems solved by technology

Since the existing circuit design methods and processing technology are still difficult to realize power dividers and directional couplers with perfect equal power division, 90° phase difference and high isolation in the broadband, the two-way quadrature mixer microwave Quadrature IF output terminals I and Q generally have amplitude and phase imbalances, and the specific values ​​change with frequency

This makes the calibration of quadrature mixers a cumbersome and demanding process for phase noise measurements of superconducting KIDs detectors

In addition, the quadrature mixer needs to excite two double-balanced mixers at the same time, and the excitation level of the local oscillator is relatively large. On the one hand, it puts forward higher requirements on the power of the frequency synthesis source; Larger DC bias limits the multiple of DC amplification and the dynamic range of the analog-digital sampling circuit

[0007] In the same-difference mixing phase noise measurement method, the measurement results of the I and Q intermediate frequency outputs must be used at the same time to accurately obtain the phase information of the KIDs detector and calculate its phase noise. This is mainly because various KIDs detector chips It is impossible to predict the phase of the entire system link due to the difference in the internal structure and the length of the connecting line

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