Marko Mailand

An effort reduced six-port direct conversion receiver and its calibration

Well-known receiver architectures, such as wideband-IF-receivers or zero-IF-receivers, usually require highly accurate component matching. For the realization of a software defined radio (SDR) device, the requirement of adjustability supervenes. Contemporarily, much effort is being made to develop tunable circuits and also to find new algorithms for digital elimination of analog signal distortions, etc. In order to reduce the effort for the analog receiver front-end and to bridge the gap between system architectures and circuit technologies, the alternative six-port receiver was investigated. Based on the six-port structure, we present a five-port receiver front-end architecture with signal path mismatch cancellation. To be able to regenerate the IQ-components, a calibration technique is presented based on the proposed architecture. Therefore, known algorithms can be utilized after the calibration. The main focus is the technical feasibility of the front-end in SDR mobile terminals.

A near-field-communication (NFC) enabled wireless fluorimeter for fully implantable biosensing applications

Remotely powered, biological-monitoring systems with a small form factor that enable long-term implantation can facilitate treatments for a variety of diseases and conditions [1,2]. This type of sensor system can also build off the standards used in near-field communications, which provide a great opportunity for communicating with battery-less sensing systems that remain dormant the majority of the time, except when activated by a host system to take measurements. This paper presents a wireless fluorimeter that enables a long-term implantable, continuous glucose-monitoring system. This work merges fluorimetry-based sensing with microsystem technology, to leverage the substantial increases in optical efficiency and provide access to applications where long-term reliability and small form factor are required [2]. Fluorescent transduction also enables full encapsulation of the electrical system, isolating it from an externally placed indicator, which needs to be in continuous equilibrium with its environment.

An NFC-Enabled CMOS IC for a Wireless Fully Implantable Glucose Sensor

This paper presents an integrated circuit (IC) that merges integrated optical and temperature transducers, optical interface circuitry, and a near-field communication (NFC)-enabled digital, wireless readout for a fully passive implantable sensor platform to measure glucose in people with diabetes. A flip-chip mounted LED and monolithically integrated photodiodes serve as the transduction front-end to enable fluorescence readout. A wide-range programmable transimpedance amplifier adapts the sensor signals to the input of an 11-bit analog-to-digital converter digitizing the measurements. Measurement readout is enabled by means of wireless backscatter modulation to a remote NFC reader. The system is able to resolve current levels of less than 10 pA with a single fluorescent measurement energy consumption of less than 1 μJ. The wireless IC is fabricated in a 0.6-μm-CMOS process and utilizes a 13.56-MHz-based ISO15693 for passive wireless readout through a NFC interface. The IC is utilized as the core interface to a fluorescent, glucose transducer to enable a fully implantable sensor-based continuous glucose monitoring system.

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.

Semi-Blind Cancellation of IQ-Imbalances

The technical realization of modern wireless receivers yields significant interfering IQ-imbalances, which have to be compensated digitally. To cancel these IQ-imbalances, we propose an algorithm using iterative blind source separation (IBSS) as well as information about the modulation scheme used (hence the term semi-blind). The novelty of our approach lies in the fact that we match the nonlinearity involved in the IBSS algorithm to the probability density function of the source signals. Moreover, we use approximations of the ideal non-linearity to achieve low computational complexity. For severe IQ-mismatch, the algorithm leads to 0.2 dB insertion loss in an AWGN channel and with 16-QAM modulation.

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.