Whitepapers

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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Reinventing the Transmit Chain for Next-Generation

Upcoming generations of radio access standards are placing high demands on the RF transmit chain, requiring significant improvements in size, integration, and functionality while improving power efficiency for multimode wireless devices. To date, trends in RF integration have been to add redundant circuits to accommodate new standards, packing more complexity into the circuit, and then shrinking it. However, this approach often requires a necessary compromise in performance and yield, with physical limits in terms of overall size reductions. A new approach is needed that incorporates a streamlined architecture to accommodate the additional levels of complexity due to multimode functionality, while improving efficiency, yield, and size, and meeting regulatory compliance.
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Super-regenerative Receiver

This article describes the super-regenerative receiver (SRR), a device widely used in short distance telemetry and remote control applications. The difficulty in modeling the regenerative behavior served as the basis for “cut and try” methodology based on results obtained from the simplified model using a conventional approach. This work presents the SRR behavior to practical implementations by dynamically controlling the injection-mode levels of the super-regenerative oscillator (SRO) for optimum sensitivity and dynamic ranges.
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Future Technologies and Testing for Fixed Mobile Convergence, SAE and LTE in Cellular Mobile Communications.

The Mobile Communications industry is currently developing standards and solutions for the next steps in the evolution of mobile networks. This introduction looks at the fundamental radio and network technologies being introduced in these steps, and how this is aligned into the future Fixed Mobile convergence (FMC) of the Next Generation Networks.
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