Wolfgang Templ

A 1.55 GHz to 2.45 GHz center frequency continuous-time bandpass delta-sigma modulator for frequency agile transmitters

This paper presents a 4th order continuous-time bandpass delta-sigma modulator (CT-BPDSM) with a programmable center frequency ranging from 1.55 GHz to 2.45 GHz. The modulator is suited to be applied in multi-standard class-S power amplifiers. The circuit features a multi-feedback architecture with return-to-zero (RZ) and half-return-to-zero (HRZ) pulses. The loop filters consist of LC-resonators with emitter degenerated input transconductors and Q-enhancement circuits. A configuration register allows to program the resonator input transconductors, the Q-enhancement circuits and the resonator capacitances with 5 bit resolution. Fine tuning of the resonator center frequency is achieved with varactors. The circuit is implemented in a 200 GHz-fT SiGe-bipolar technology. The measured SNR at 2.2 GHz center frequency is 45.5 dB in a bandwidth of 20 MHz. At 1.55 GHz the SNR decreases to 40.7 dB. The measured uplink UMTS-FDD ACLR (adjacent channel leakage power ratio) of the modulator output is 48.4 dB in the first adjacent channel.

Continuous-Time Bandpass Delta-Sigma Modulator for a Signal Frequency of 2.2 GHz

A continuous-time bandpass delta-sigma modulator (CT BPDSM) for class-S power amplifier applications with a center frequency of 2.2 GHz is presented. Class-S amplifiers are considered to provide a very power efficient way to amplify signals with high dynamic range. The modulator has a multi-feedback architecture. It features a low noise transconductor with series emitter degeneration, tunable LC resonators with Q-enhancement and an optimized clock tree operating at 7.5 GHz. The circuit is implemented in a 200 GHz-fT SiGe-bipolar technology. A peak SNDR of 43 dB in a bandwidth of 20 MHz is measured. The circuit dissipates 450 mW from a 3.6 V supply.

E-mobility in the context of electric energy distribution grids

Mobility is an important aspect in our daily life and has a deep impact on a multitude of societal factors. For nearly 120 years, we have been heavily relying on fossil energy sources. This trend may not be sustainable in the coming decades due to shortage of resources as well as ambitious goals for environmental protection. In this situation, electric vehicles could play a key role in maintaining our high level of individual mobility. After an introduction briefly depicting the motivation for change, this paper presents a state of the art analysis of the concepts driving increased deployment of electric vehicles. Based on an estimated rollout scenario of electric mobility (e-mobility) in Germany we discuss its impact on the electricity distribution grid. An algorithm for estimating energy demands caused by electric vehicles in time and location is proposed. Movement scenarios are investigated, and key parameters are defined as a baseline for this algorithm.

Graphene-based integrated photonics for next-generation datacom and telecom

Graphene is an ideal material for optoelectronic applications. Its photonic properties give several advantages and complementarities over Si photonics. For example, graphene enables both electro-absorption and electro-refraction modulation with an electro-optical index change exceeding 10−3. It can be used for optical add–drop multiplexing with voltage control, eliminating the current dissipation used for the thermal detuning of microresonators, and for thermoelectric-based ultrafast optical detectors that generate a voltage without transimpedance amplifiers. Here, we present our vision for graphene-based integrated photonics. We review graphene-based transceivers and compare them with existing technologies. Strategies for improving power consumption, manufacturability and wafer-scale integration are addressed. We outline a roadmap of the technological requirements to meet the demands of the datacom and telecom markets. We show that graphene-based integrated photonics could enable ultrahigh spatial bandwidth density, low power consumption for board connectivity and connectivity between data centres, access networks and metropolitan, core, regional and long-haul optical communications.Graphene-integrated photonics is a platform for wafer-scale manufacturing of modulators, detectors and switches for next-generation datacom and telecom systems. This Review describes how these functions can be achieved with graphene layers placed on top of optical waveguides, acting as passive light guides, thus simplifying the current technology. In addition, a roadmap of the technological requirements for the datacom and telecom markets is presented.