Raik Richter

An integrated wideband-IF-receiver architecture for mobile terminals

A wideband-IF receiver architecture is described for use in mobile terminals capable of receiving multiple standards like GSM, UMTS, DECT, etc. The architecture uses a single down-conversion and digitizes the wanted signal at high intermediate frequencies. The wideband nature of the architecture ensures a great adaptability to various mobile standards. It denotes a step into the direction of a fully reconfigurable software radio due to the shift of the ADC to higher frequencies. The paper is focused on the realization of the analog part of the receiver.

A virtual clock enhancement method for DDS using an analog delay line

In this paper, we describe an analog delay line (DL) used for virtual clock enhancement in a direct digital synthesis (DDS). The novelty of the proposed method is the immediate application of the output signal of the phase accumulator for the generation of the desired frequency. To obtain the necessary spectral purity of the generated frequency, additional digital signal processing (DSP) based on a delay-locked loop (DLL) and noise shaping is applied. The consequences of nonlinear effects within the DL for the spectral performance of the DDS are explained.

Nonlinearity analysis of power detectors in direct conversion receivers utilizing six-port technology

Within the six-port or five-port receiver, additive mixing followed by squaring of the respective signal is realized. For the squaring, power detectors are utilized. In this article, we investigate the influence of higher order nonlinearities of the power detectors. The focus is on the distortion of the baseband signal by nonlinear fractions which originate from the RF-signal. Among other things, it will be deviated that even the most simple power detector realizations can guarantee a sufficient transmission quality.

A flexible, programmable sensor signal conditioning IC for high-precision smart sensors

System performance and realizability of smart sensors all depend on proper analog-digital signal processing. This paper presents a sensor signal conditioning IC using standard 0.18um CMOS technology which delivers 16bit-precise measurement results for resistive bridge-type sensors via a serial digital interface. The presented IC, ZSSC3016 can operate in applications with poor power supply while consuming a minimum of current. A general motivation for sensor signal conditioning is given. The system architecture, main functional blocks and simulation and measurement results are shown and described.

Six-Port Architecture based Receiver for MB-OFDM UWB Systems

In this paper, we present the investigation of a six-port architecture based receiver for multi-band OFDM ultra- wide band (UWB) systems. An UWB system simulator is implemented in MATLAB for specification compliant signal processing according to and is represented by transmitter and receiver models. A six-port based receiver is presented which is used in the RF front-end of an UWB system. Its model includes six-port specific errors addressed in following case studies. Additionally, a performance influencing receiver environment is taken into account when we investigate the suitability of six-port architecture for UWB. We conclude this work by system performance evaluation under the considered application scenario.

A standard low-noise sensor interface for 0.66nJ/step-energy-efficient, mobile barometric-pressure-based altitude sensing

This paper presents a mixed-signal sensor interface IC on only 1.5mm2-silicon that delivers almost 16-bit-precise measurement results for resistive bridge-type sensors. The IC integrates a programmable ratiometric analog interface and contains a digital calculation unit for sensor-nonlinearity and temperature dependency compensation. A low-dropout regulator allows the usability of a respective smart sensor in dirty-supply applications without requiring external stabilization components. The IC allows for a new performance level of mobile barometric pressure sensing due to the combination of external component-free power supply rejection, specific analog/digital signal processing and a stringent energy efficiency approach. A figure-of-merit of only 0.66nJ/step is achieved. The absolute accuracy of ±0.5hPa can lead to altitude measurements in the range of -500m to 10km with 8cm-resolution.