Hermann Schumacher

Enhanced SiGe heterojunction bipolar transistors with 160 GHz-f/sub max/

Double-mesa type SiGe heterojunction bipolar transistors (HBTs) have been improved by increasing the base Gummel number and by using a thin, highly doped launcher layer between the base and the collector. In addition, the contact resistance of the base contact has been reduced. Hence, it was possible to obtain a record maximum frequency of oscillation up to 160 GHz for a 2-emitter finger HBT in common emitter configuration.

Transmission lines and passive elements for multilayer coplanar circuits on silicon

In this paper, propagation properties of both standard and multilayer coplanar lines on different types of silicon substrates, as well as a number of quasi-lumped and stub-type circuit elements, are investigated. For the transmission lines, emphasis is placed on losses. As examples for circuit elements, a lumped parallel resonator and a high-low impedance low-pass filter are demonstrated.

IR-UWB Radar Demonstrator for Ultra-Fine Movement Detection and Vital-Sign Monitoring

In this paper an impulse-radio ultra-wideband (IR-UWB) hardware demonstrator is presented, which can be used as a radar sensor for highly precise object tracking and breath-rate sensing. The hardware consists of an impulse generator integrated circuit (IC) in the transmitter and a correlator IC with an integrating baseband circuit as correlation receiver. The radiated impulse is close to a fifth Gaussian derivative impulse with σ = 51 ps, efficiently using the Federal Communications Commission indoor mask. A detailed evaluation of the hardware is given. For the tracking, an impulse train is radiated by the transmitter, and the reflections of objects in front of the sensor are collected by the receiver. With the reflected signals, a continuous hardware correlation is computed by a sweeping impulse correlation. The correlation is applied to avoid sampling of the RF impulse with picosecond precision. To localize objects precisely in front of the sensor, three impulse tracking methods are compared: Tracking of the maximum impulse peak, tracking of the impulse slope, and a slope-to-slope tracking of the objects reflection and the signal of the static direct coupling between transmit and receive antenna; the slope-to-slope tracking showing the best performance. The precision of the sensor is shown by a measurement with a metal plate of 1-mm sinusoidal deviation, which is clearly resolved. Further measurements verify the use of the demonstrated principle as a breathing sensor. The breathing signals of male humans and a seven-week-old infant are presented, qualifying the IR-UWB radar principle as a useful tool for breath-rate determination.

SiGe-technology and components for mobile communication systems

SiGe-HBTs offer the opportunity to build integrated front-ends for mobile communication systems above 1 GHz. SiGe-HBTs with 50 GHz f/sub T/ and f/sub max/ were obtained by a production process including poly-silicon resistors, nitride capacitors and spiral inductors showing Q values up to 10. RF-noise figures down to 1 dB at 2 GHz with an associated gain of 14 dB and 1 Hz 1/f corner frequency were obtained. Class A load pull measurements on power SiGe-HBTs at 1.9 GHz exhibited a power added efficiency (PAE) of 44% at 1W RF output power. Power amplifiers, low noise amplifiers and mixer circuits are presently under investigation.

Monolithic Integration of a Folded Dipole Antenna With a 24-GHz Receiver in SiGe HBT Technology

The integration of an on-chip folded dipole antenna with a monolithic 24-GHz receiver manufactured in a 0.8-mum SiGe HBT process is presented. A high-resistivity silicon substrate (1000 Omega ldr cm) is used for the implemented circuit to improve the efficiency of the integrated antenna. Crosstalk between the antenna and spiral inductors is analyzed and isolation techniques are described. The receiver, including the receive and an optional transmit antenna, requires a chip area of 4.5 mm2 and provides 30-dB conversion gain at 24 GHz with a power consumption of 960 mW.

FCC compliant 3.1-10.6 GHz UWB Pulse Radar System using Correlation Detection

A short range 3.1-10.6 GHz single band ultra-wideband (UWB) pulse radar system is presented. The transmitter consists of a pulse generator that is connected to a broadband monopole antenna. The generated pulse shape is similar to the fifth derivative of the Gaussian bell shape and makes efficient use of the allocated FCC UWB frequency mask. The receiver is realized with a single-ended low noise amplifier and active single-ended to differential converters that drive the input ports of an analog correlator which uses pulse sequences as template signals. Measurements show a resolution capability of the radar system in the millimeter range. All active circuits have been realized in a low cost 0.8 mum SiGe HBT technology.

A single-chip 24 GHz receiver front-end using a commercially available SiGe HBT foundry process

The authors have demonstrated a fully integrated receiver frontend addressing the ISM-Band at 24 GHz utilizing a standard SiGe HBT MMIC process with a relaxed emitter scaling of 1.2 /spl mu/m, for the first time. Extremely compact circuit design and layout techniques are applied to a mature Si/SiGe technology, resulting in a low-cost integrated circuit enabling consumer-oriented systems at Ka band. The integrated components are a preamplifier, a mixer with an IF buffer and a local oscillator. The conversion gain is determined to be 16.3 dB for an intermediate frequency of 100 MHz.

Compact multilayer filter structures for coplanar MMICs

Coplanar filter structures busing two metallization layers separated by a polyimide film on GaAs were investigated. This arrangement provides additional degrees of freedom compared to the standard coplanar line, resulting in extremely compact filters suitable for monolithic integration.<<ETX>>

Investigation of microstrip and coplanar transmission lines on lossy silicon substrates without backside metallization

Silicon circuits, now penetrating well into the microwave frequency range, use lossy silicon substrates. Consequently, the microwave performance of transmission lines on this substrate becomes increasingly important and has been investigated here up to 20 GHz. It is shown that transmission lines on 20-/spl Omega//spl middot/cm substrates have no need for backside metallization and backside via holes. Two models for different line types are derived from measurements and verified against them. A coplanar waveguide (CPW) with an overall width of less than 30 /spl mu/m was fabricated with an attenuation of 0.5 dB/mm at 20 GHz, which is acceptable for monolithic microwave integrated circuit (MMIC) design.

Low-noise performance of SiGe heterojunction bipolar transistors

We have demonstrated, for the first time, a microwave noise figure below 1 dB at 10 GHz from a heterojunction bipolar transistor. The current and frequency dependence of the results obtained agree with the well-established Hawkins theory for bipolar transistor noise performance. An enhanced equivalent noise circuit including major parasitics provides valuable insight for the optimization of these devices for low-noise operation. Typical applications may include integrated RF front-ends where low-noise amplification is desired in addition to low phase-noise oscillation and mixing which typically benefit from bipolar devices.<<ETX>>