J. Buechler

Si/SiGe MMIC's

Silicon-based millimeter-wave integrated circuits (SIMMWICs) can provide new solutions for near range sensor and communication applications in the frequency range above 50 GHz. This paper presents a survey on the state-of-the-art performance of this technology and on first applications, The key devices are IMPATT diodes for MM-wave power generation and detection in the self-oscillating mixer mode, p-i-n diodes for use in switches and phase shifters, and Schottky diodes in detector and mixer circuits. The silicon/silicon germanium heterobipolar transistor (SiGe HBT) with f/sub max/ values of more than 90 GHz is now used for low-noise oscillators at Ka-band frequencies. First system applications are discussed. >

SIMMWIC rectennas on high-resistivity silicon and CMOS compatibility

Rectifying antennas (rectennas) are realized on high-resistivity silicon substrates using silicon monolithic millimeter-wave integrated circuit (SIMMWIC) technology. Monolithically integrated coplanar Schottky barrier diodes are used as rectifying elements embedded in different antenna structures. Both p- and n-type Schottky barrier diodes are realized with cutoff frequencies up to 1 THz. The rectennas are combined with a CMOS preamplifier mounted as a multichip module (MCM) next to the rectenna on a high-resistivity silicon substrate. An amplification of 32 dB is measured. Maximum sensitivity of the detector circuit including preamplification is 1600 mV/mW/spl middot/cm/sup -2/ at 94.6 GHz. For a monolithic integration of high-frequency circuits with low-frequency control and signal-processing electronics, the monolithic integration of CMOS circuitry on high-resistivity silicon is discussed.

A monolithic integrated millimeter wave transmitter for automotive applications

An integrated transmitter at 80 GHz is presented. This device finds many applications in civil sensor and communication systems, and is employed in automotive applications. The device consists of an IMPATT diode and a slotted patch resonator. The resonator acts simultaneously as an antenna. The resonator impedance seen by the IMPATT diode is calculated by means of a full wave analysis and the matching of the IMPATT diode is investigated using a large signal analysis. The transmitter devices have been fabricated employing a SIMMWIC (silicon millimeter wave integrated circuit) fabrication process and deliver a radiated power of up to 1 mW at 79 GHz. An excellent carrier-to-noise ratio of 81.7 dBc/Hz at an offset of 100 kHz has been achieved. The deviation of the measured values from the theoretically predicted values of frequency and power is -5.9% and -1.5 dB, respectively. >

Multifunctional radar sensor for automotive application

A multifunctional radar system for vehicles consisting of two modules with a combined bistatic/monostatic arrangement is presented. One module acts as a transceiver, whereas the other is a receiving circuit. The transmitting part radiates a frequency-modulated signal alternately in two orthogonal polarizations. The receiving parts work with different local oscillator (LO) frequencies and detect both polarizations of the scattered signal simultaneously. From the resulting Doppler spectra and a distance measurement, the velocity, tilt angle, height with respect to ground, and the direction of the movement of a vehicle can be derived. From the polarimetric information, a classification of the road condition is possible. In a first approach, the sensor was built in a conventional waveguide technique. The second step was to realize the millimeter-wave circuits of both modules with monolithic silicon millimeter-wave integrated circuit (SIMMWIC) technology. To achieve a flat arrangement, a leaky-wave antenna is developed and coupled to the SIMMWICs.

Coplanar Monolithic Silicon Impatt Transmitter

A coplanar W-band transmitter incorporating a monolithically integrated IMPATT diode in a self radiating slot line resonator has been designed and fabricated with molecular beam epitaxy (MBE) on a high resistivity silicon substrate. A pulsed radiated output power of 7 mW at 109 GHz was measured.

A Silicon Technology for Active High Frequency Circuits

Monolithic integrated IMPATT diodes are manufactured as millimeter wave power generators in slot line resonator-antennas. Silicon molecular beam epitaxy (Si-MBE) is used for the growth of the active layers. A fabrication process with a self stopping etchant, self aligned contacts, silicon nitride passivation and air-bridge technology is used. The emitted radiation of the millimeter wave transmitter chip is 2.6 mW at 90.6 GHz in cw-operation and 50 mW at 92 GHz in pulsed operation.

A pre-crash radar sensor system based on pseudo-noise coding

A pre-crash radar sensor system measuring closing velocity and range, working at 24 GHz is presented. The radar is based on spread spectrum modulation using a 1023 long pseudo-noise sequence at a 450 Mbps data rate. The achieved resolution of 33 cm is also suitable for object identification applications in a driving environment. The time delay of the noise sequence in the correlation receiver covers the entire unambiguous range. The construction of the sensor, strategy of application and measurement results are presented.

Two frequency multifunctional radar for mobile application

A radar system for vehicles is presented working with two modules at different frequencies and a special arrangement of the modules. From the resulting Doppler spectra in the baseband and in the IF band the velocity, the tilt angle and the height with respect to ground, the direction of the movement of a vehicle and the classification of the road condition can be derived. Even if the baseband signals fail because of plane surfaces like a puddle the velocity can be extracted. This millimeter wave radar system was conceived to measure the velocity and at the same time to increase the performance of a simple Doppler radar.

An Experimental 24 GHz Radar using Phase Modulation Spread Spectrum Techniques

In this contribution, an experimental bistatic radar sensor at 24 GHz is described, based on phase coded spread spectrum modulation. The sensor uses a code clock rate of200MHz and a code length of 1023, resulting in a range resolution (for two targets) of 1.5 m andan unambiguous range ofabout 750 m. The digital signal modulates a 1.6 GHz signal which then is upconverted to 24 GHz. The received signal is downconverted to an IF frequency of 1.6 GHz and then demodulated with the reference frequency of 1.6 GHz, modulated with a delayed phase code. The setup of the digital part as well as the microwave part of the sensor will be described together with first test results.

Coplanar SIMMWIC circuits

Using silicon as the substrate material SIMMWIC (Silicon Monolithic Millimeter Wave Integrated Circuit) oscillators and receivers are successfully realized. For the coplanar oscillators a slot is used as the resonant structure in which a monolithically integrated IMPATT diode selectively grown by Silicon molecular beam epitaxy (Si-MBE) acts as the negative resistance device. Pulsed and CW operation of the planar oscillators is achieved in the 90 GHz region. The output power is either radiated from a planar Vivaldi antenna or directly from the resonant slot. Complete receivers with monolithic Schottky diodes together with the antenna are integrated on a single chip.