Eravant’s STZ Series of noise source products offers a diverse range to meet various Test & Measurement requirements within the frequency range of 0.5 to 220 GHz. Typically, coaxial connector-based noise sources are available for frequencies below 67 GHz, while waveguide versions cater to the 18 to 220 GHz range. The Excess Noise Ratios (ENR) of these STZ models range from 12 to 20 dB. For the waveguide noise sources, there's a typical ENR flatness of ±2 dB across the entire operating bandwidth. The ENR calibration for waveguide models was achieved using the Liquid Nitrogen (LN2)-based true cold/hot termination method.
All models necessitate a nominal supply voltage of +28 VDC. All models are equipped with either a Faraday isolator or an internal attenuator to offer high return loss and isolate the port impedance variations, ensuring a consistent flat ENR across frequency bands. The STZ series includes different RF ports and operates across various frequency bands, as detailed in Table 1.
Furthermore, these noise sources support TTL-level input for on/off control signals and can accommodate modulation rates of up to 1 kHz. In addition, a manual toggle switch is provided conveniently to turn the noise source on and off. The specific specifications for the D-band STZ model are detailed in Table 2, illustrating an example of calibrated ENR, as depicted in Figure 2, showcasing a typical ENR of 15 dB.
Noise sources play a pivotal role in various Test & Measurement applications. Primarily, they serve as reference signals to measure internally generated noise levels in components, subsystems and systems. These sources are adept at providing wide-band stimulus signals for built-in test functions in radar and communication systems, and they contribute to assessing the linearity and stability of high-power amplifiers. Moreover, they are integral components utilized in the calibration circuitry of microwave radiometers and radio astronomy receivers. The noise source functions by injecting a predetermined and known amount of noise power into the receiver. This injected noise power enables the testing of the receiver's output power, thereby determining the receiver's gain and allowing for the calibration of its variance. Additionally, the noise source can be toggled on and off, supplying two different levels of injected power. This approach yields two corresponding output power levels, facilitating the acquisition of both the gain and noise figure of the receiver. Consequently, this comprehensive process enables the complete calibration of the receiver system.
With the advancements in millimeter-wave and sub-terahertz technologies, there's a growing demand for noise sources operating at frequencies beyond the W-band (75-110 GHz). Presently, the discussions around 6G at the D-band (110-170 GHz) are burgeoning, leading to the development of numerous systems tailored for various applications. The assessment of gain and noise figures for these systems is crucial for validation and testing. Consequently, D-band noise sources are garnering increased attention from both academic and industrial circles. Yet, commercial noise sources capable of covering the entire sub-terahertz frequency bands are presently not widely available.
Eravant not only offers calibrated noise sources but also provides noise source calibration services. Eravant has adopted the Y-factor method to determine the ENR of a noise source under test. To ascertain the noise temperature of the device under test (DUT) requires a reference noise source with a known noise temperature. This method utilizes a liquid nitrogen-cooled termination as the cold state of the reference noise source with a noise temperature of 77K and a room temperature termination as the hot state with a noise temperature of 290K. Noise power readings from the reference noise source are collected by the noise figure measurement system at its hot and cold states, normalizing the noise figure of the measurement system. By gathering noise power readings from the noise source under test in its on and off states, the ENR of the DUT can be calculated, completing the calibration process. The effective noise temperatures of these terminations are meticulously regulated and measured with high precision to ensure the accuracy and reliability of noise source calibrations.
Calibrated D-Band STZ ENR
Signal analyzers and noise figure analyzers that are currently available lack the direct capability to measure noise power within the mmWave and sub-THz frequency ranges. To facilitate noise figure measurements in these frequency ranges, integrating down-converters within the measuring system is essential. Eravant offers full waveguide band down-converters extending the operating frequency of the analyzers up to 220 GHz and typically providing a conversion gain from 20 to 30 dB.
Eravant provides a comprehensive solution set for mmWave and sub-THz frequency challenges. Critical to these solutions are noise sources. In addition to noise sources with flat ENRs, they offer calibration services for waveguide-banded noise sources. Eravant also supplies down-converters for precise noise figures and gain measurements up to 220 GHz.
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