Whitepapers

The Perils of Spectrum Analyzer Power Averaging

Averaging is a common technique for reducing the measurement uncertainty inherent in all measurements. Performing the same measurement a number of times and calculating the average of the measured values can often reduce the randomness of an experimental result. However, not all power averaging techniques give the same results. This paper dicusses the differences.
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EM Analysis within the Design Flow

Prior to the circuit design and especially in larger designs, EM tools are used to create “library” parts such as inductors, transitions and antennas. While these parts are fairly self-contained, they must ultimately be integrated into the overall design where at the very least they must be connected to the rest of the circuit or in a more complex case be coupled to it. During both early and later stages of design, designers will switch from circuit-based models to EM analysis of critical interconnects to better understand couplings and achieve greater accuracy.
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Correcting Imperfections in IQ Modulators Improves RF Signal Fidelity

This article will begin by describing a typical Zero-IF or direct-conversion transmitter along with providing a brief introduction to digital modulation. The imperfections introduced by the modulator will be examined with particular focus on the effect of temperature and frequency changes. In-Factory and In-Field algorithms that can reduce the effect of these modulator imperfections will also be discussed. Particular focus will be placed on the efficacy of In-Factory “set-and-forget” algorithms.
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Rohde & Schwarz Develops a New Technique for Group Delay Measurements without LO Access

This paper describes a technique developed by Rohde & Schwarz for the network analyzers of the R&S®ZVA family: It allows high-precision group delay measurements of converters and mixers even without access to the local oscillator or the reference signal. This technique uses a two-tone signal to stimulate the mixer or converter. The phase difference between these two carriers is measured at the input and the output of the DUT (device under test) to calculate the group delay from the phase shift caused by the DUT.
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Phase Coherent Multi-channel RF Synthesis

The phase-locked loop (PLL) has been widely used in traditional tunable RF synthesis design to maintain a “fixed” phase relationship between a generated (output) frequency and that of a reference signal. Although a properly designed PLL is an effective method for maintaining a fixed frequency, it does not allow for fully monotonic phasing in applications where phase coherence is critical.
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IP2 and IP3 Nonlinearity Specifications for 3G/WCDMA Receivers

The complete analysis of the nonlinearity requirements of a WCDMA direct conversion (Zero-IF) receiver is presented. This paper focuses on IP2 and IP3 requirements and covers all test cases defined in 3GPP, such as TX leakage, Intermodulation, Adjacent channel blocking, Narrow band blocking, In-band and Out of band blocking etc. The two tone IP2 and IP3 concept is further expanded into modulated signals. The formulas for computing IP2 and IP3 with modulated signals for different test cases are presented.
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Utilizing Time Domain (TDR) Test Methods

Time Domain Reflectometry (TDR) is a very useful tool for designing transitions such as the transition between coaxial connectors and PC boards. The TDR function will display the impedance over time showing the place and nature of discontinuities that are due to impedance changes. This paper discusses the aspects of TDR measurements that are relevant to the analysis of a transition.
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