Coplanar waveguide

About: Coplanar waveguide is a research topic. Over the lifetime, 9375 publications have been published within this topic receiving 117113 citations.

Terahertz attenuation and dispersion characteristics of coplanar transmission lines

Abstract: Experimental verification of analytic formulas for the dispersion and the attenuation of electrical transient signals propagating on coplanar transmission lines is presented. The verification is done in the frequency domain over a terahertz range although the experiments are in the time domain. The analytic formulas are obtained from fits to the full-wave analysis results. It is quantitatively verified that the full-wave steady-state solutions can be directly applied to the transient time-domain propagation experiments. Subpicosecond electrical pulses and an external electrooptic sampling technique are used to obtain the time-domain propagation data. From the Fourier transforms of the time-domain data both the attenuation and the phase information as a function of frequency are extracted. The dispersion and the attenuation characteristics are investigated for both coplanar waveguide and coplanar strip transmission lines. The investigation is carried out on both semiinsulating semiconductor and dielectric substrate materials. No observable losses caused by the semiconductor material are indicated. >

Coplanar waveguide resonators for circuit quantum electrodynamics

Abstract: High quality on-chip microwave resonators have recently found prominent new applications in quantum optics and quantum information processing experiments with superconducting electronic circuits, a field now known as circuit quantum electrodynamics (QED). They are also used as single photon detectors and parametric amplifiers. Here we analyze the physical properties of coplanar waveguide resonators and their relation to the materials properties for use in circuit QED. We have designed and fabricated resonators with fundamental frequencies from 2 to 9 GHz and quality factors ranging from a few hundreds to a several hundred thousands controlled by appropriately designed input and output coupling capacitors. The microwave transmission spectra measured at temperatures of 20 mK are shown to be in good agreement with theoretical lumped element and distributed element transmission matrix models. In particular, the experimentally determined resonance frequencies, quality factors, and insertion losses are fully and consistently explained by the two models for all measured devices. The high level of control and flexibility in design renders these resonators ideal for storing and manipulating quantum electromagnetic fields in integrated superconducting electronic circuits.

Planar Superconducting Resonators with Internal Quality Factors above One Million

Abstract: We describe the fabrication and measurement of microwave coplanar waveguide resonators with internal quality factors above 10 million at high microwave powers and over 1 million at low powers, with the best low power results approaching 2 million, corresponding to ~1 photon in the resonator. These quality factors are achieved by controllably producing very smooth and clean interfaces between the resonators' aluminum metallization and the underlying single crystal sapphire substrate. Additionally, we describe a method for analyzing the resonator microwave response, with which we can directly determine the internal quality factor and frequency of a resonator embedded in an imperfect measurement circuit.

Shielded passive devices for silicon-based monolithic microwave and millimeter-wave integrated circuits

Abstract: This paper introduces floating shields for on-chip transmission lines, inductors, and transformers implemented in production silicon CMOS or BiCMOS technologies. The shield minimizes losses without requiring an explicit on-chip ground connection. Experimental measurements demonstrate Q-factor ranging from 25 to 35 between 15 and 40 GHz for shielded coplanar waveguide fabricated on 10 /spl Omega//spl middot/cm silicon. This is more than a factor of 2 improvement over conventional on-chip transmission lines (e.g., microstrip, CPW). A floating-shielded, differentially driven 7.4-nH inductor demonstrates a peak Q of 32, which is 35% higher than an unshielded example. Similar results are realizable for on-chip transformers. Floating-shielded bond-pads with 15% less parasitic capacitance and over 60% higher shunt equivalent resistance compared to conventional shielded bondpads are also described. Implementation of floating shields is compatible with current and projected design constraints for production deep-submicron silicon technologies without process modifications. Application examples of floating-shielded passives implemented in a 0.18-/spl mu/m SiGe-BiCMOS are presented, including a 21-26-GHz power amplifier with 23-dBm output at 20% PAE (at 22 GHz), and a 17-GHz WLAN image-reject receiver MMIC which dissipates less than 65 mW from a 2-V supply.

Microwave dielectric loss at single photon energies and millikelvin temperatures

Abstract: The microwave performance of amorphous dielectric materials at very low temperatures and very low excitation strengths displays significant excess loss. Here, we present the loss tangents of some common amorphous and crystalline dielectrics, measured at low temperatures (T<100mK) with near single-photon excitation energies, E∕ℏω0∼1, using both coplanar waveguide and lumped LC resonators. The loss can be understood using a two-level state defect model. A circuit analysis of the half-wavelength resonators we used is outlined, and the energy dissipation of such a resonator on a multilayered dielectric substrate is theoretically considered.