Abstract Sensitive dispersive readouts of single-electron devices (“gate reflectometry”) rely on one-port radio-frequency (RF) reflectometry to read out the state of the sensor. A standard practice in reflectometry measurements is to design an impedance transformer to match the impedance of the load to the characteristic impedance of the transmission line and thus obtain the best sensitivity and signal-to-noise ratio. This is particularly important for measuring large impedances, typical for dispersive readouts of single-electron devices because even a small mismatch will cause a strong signal degradation. When performing RF measurements, a calibration and error correction of the measurement apparatus must be performed in order to remove errors caused by unavoidable non-idealities of the measurement system. Lack of calibration makes optimizing a matching network difficult and ambiguous, and it also prevents a direct quantitative comparison between measurements taken of different devices or on different systems. We propose and demonstrate a simple straightforward method to design and optimize a pi matching network for readouts of devices with large impedance, $$Z \ge 1\hbox {M}\Omega$$ Z ≥ 1 M Ω . It is based on a single low temperature calibrated measurement of an unadjusted network composed of a single L-section followed by a simple calculation to determine a value of the “balancing” capacitor needed to achieve matching conditions for a pi network. We demonstrate that the proposed calibration/error correction technique can be directly applied at low temperature using inexpensive calibration standards. Using proper modeling of the matching networks adjusted for low temperature operation the measurement system can be easily optimized to achieve the best conditions for energy transfer and targeted bandwidth, and can be used for quantitative measurements of the device impedance. In this work we use gate reflectometry to readout the signal generated by arrays of parallel-connected Al-AlOx single-electron boxes. Such arrays can be used as a fast nanoscale voltage sensor for scanning probe applications. We perform measurements of sensitivity and bandwidth for various settings of the matching network connected to arrays and obtain strong agreement with the simulations.
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This content will become publicly available on June 16, 2024
Validity of room-temperature calibration for on-wafer measurements up to 220 GHz, 125 °C, and 48 h
At-temperature calibration is not only inconvenient, but also complicated by the temperature dependence of impedance standards. This paper examines the validity of a room-temperature calibration for on-wafer measurements from 70 kHz to 220 GHz, from 25 °C to 125 °C, and up to 48 h. The results indicate that the room-temperature calibration is applicable up to 125 °C provided errors up to 0.5 dB in magnitude and 5° in phase are tolerable. Consistent with previous reports up to 110 GHz, the present errors are mainly caused by the time-dependent system drift instead of the temperature dependence of impedance standards. For unknown reasons, the system proven to be stable at room temperature drifts significantly at elevated temperatures. This makes elevated-temperature measurements challenging because presently it takes approximately three hours for the system to stabilize at a new temperature. Therefore, in the near future, efforts should be concentrated on stabilizing the system faster rather than correcting for the temperature dependence of impedance standards.
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- NSF-PAR ID:
- 10442658
- Date Published:
- Journal Name:
- ARFTG Microw. Meas. Conf., San Diego, USA, Jun. 2023
- Page Range / eLocation ID:
- 1-4
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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