Erich Kolmhofer

A 77GHz 4-channel automotive radar transceiver in SiGe

A fully integrated 4-channel automotive radar transceiver chip, integrated in a 200-GHz SiGe:C production technology, is presented. With a typical transmit power of 2 x +7 dBm at the antenna ports and all functions active, the chip draws a current of about 600 mA from a single 5.5 V supply. The design permits FMCW operation in the 76 to 77 GHz band at chip-backside temperatures from -40degC to +125degC.

Three-channel 77 GHz automotive radar transmitter in plastic package

We present a three-channel 77GHz radar transmitter in an embedded wafer-level ball grid array (eWLB) package. The circuit is manufactured in a 0.35 μm SiGe bipolar process. It contains a 77GHz push-push oscillator and three independent power amplifiers with digital power control and a maximum output power of 11.7 dBm. Various frequency divider stages and an additional 18GHz oscillator and down-converter allow the realisation of single-loop and offset PLLs. The 77GHz and 18 GHz oscillators achieve a phase noise of -76 dBc/Hz and -93 dBc/Hz, at 100 kHz offset, respectively. The transmitter operates with a supply voltage of 3.3V and consumes between 205mA and 710 mA, depending on the configuration.

SiGe Circuits for Automotive Radar

This paper presents circuits in SiGe bipolar technology for automotive radar applications at 77 GHz. They cover the transmit and receive path of typical radar sensors and include a voltage-controlled oscillator with integrated power amplifier and frequency divider, an active mixer and a low-noise amplifier

A wide band transition from waveguide to differential microstrip lines

A novel transition from rectangular waveguide to differential microstrip lines is illustrated in this paper. It transfers the dominant TE10 mode signal in a rectangular waveguide to a differential mode signal in the coupled microstrip lines. The common mode signal in the coupled microstrip lines is highly rejected. The transition was designed at 75 GHz, which is the center frequency of E band and simulated by a 3D EM simulator. It has a wide bandwidth of 19 GHz for -15 dB return loss of the waveguide port. Several prototypes of the transitions were fabricated and measured. The measurement results agree very well with the simulation. The compact size and the simple fabrication enable the transition to be employed in a number of millimeter-wave applications.

Fast 77 GHz chirps with direct digital synthesis and phase locked loop

In automotive radar systems in the 77 GHz range, integrated VCOs based on silicon germanium become more and more state-of-the-art. In the application of a frequency modulated continuous wave radar, a precise frequency modulation is a prerequisite for accurate measurements. In this paper, we investigate different topologies for the linearization of high frequency sweeps based on a direct digital synthesizer and an integer-N-PLL. The obtained results are viewed in terms of the phase deviation from the theoretical course.

A heterodyne 77-GHz FMCW radar with offset PLL frequency stabilization

This contribution describes the realization of a heterodyne frequency-modulated continuous-wave (FMCW) radar system operating in the frequency band from 76 GHz to 77 GHz. To implement the heterodyne principle two voltage controlled oscillators (VCOs) are operated in order to produce frequency ramp signals with a fixed frequency offset. This allows to mitigate effects occurring in homodyne systems like, e.g., DC-offsets or low-frequency noise components. To avoid large divider values in the control loop the presented system is based on an offset phase-locked-loop configuration. In the presented implementation the same downconverter is used to implement the offset-loop for both VCOs, which has the positive effect that errors and noise influences in the downconversion process—at least partly—cancel out in the final FMCW output signal.

A 77-GHz SiGe frequency multiplier (×18) for radar transceivers

For 77-GHz automotive radar applications, a monolithic frequency multiplier with a multiplication factor of 18 is presented. The main circuit of the multiplier chain consists of two frequency tripler and one doubler. Additionally interstage amplifiers and filters are integrated in a 200-GHz SiGe:C production technology. The output power is −1dBm for a wide input power range (−20dBm − +8 dBm) at room temperature and 76.5 GHz output frequency. The output power flatness is better than 2 dB for an output frequency range of 69 GHz to 80 GHz. The power consumption of the multiplier is 170mW at a single supply voltage of 3.3V.

Monolithic integration of microstrip line couplers for automotive radar applications at 77 GHz using a Si-HBT technology

A branch-line, rat-race and a reduced-size branch-line coupler have been realized in a modern SiGe:C bipolar technology for application in automotive radar systems at 77 GHz. The paper describes the design methodology of passive circuits on lossy Si-based substrate up to 110 GHz and gives measurement results of the manufactured circuits.

Six-Port Receiver and Frequency Measurement for Radar Applications at 35GHz

The application of a six-port technology in the receiving part of a radar front-end is described in this paper. This receiver allows measuring magnitude and phase of the radar signal without the need of down-conversion. According to the applications and the availability of the devices needed for assembling the prototype sensor, the frequency of operation was set to 35GHz. The structure of this six-port as well as the calibration and measurement algorithms are described in detail. The accuracy of the phase measurement is 2–10° depending on the power level of the signal. Another key element of the proposed radar sensor is a direct frequency counter. Using this circuit it is possible to measure the frequency of operation with a resolution of 20 bits within 120μs. The accuracy of the distance reading of the radar is directly related to the accuracy of the frequency measurement and has reached 0.1mm.

Amplitude noise measurement of an automotive 77-GHz VCO

A precise and sensitive amplitude (AM) noise measurement technique is introduced for millimeter-wave signal sources. The detrimental effect of phase noise on the measurement result is analyzed and discussed. Measured results for the transmit output of a 77-GHz automotive radar transmitter chip are shown, and the contribution of the phase noise is estimated.