2019, Schmalz, K., Rothbart, N., Eissa, M.H., Borngräber, J., Kissinger, D., Hübers, H.-W.

This paper presents transmitter and receiver components for a gas spectroscopy system. The components are fabricated in IHP's 0.13 μm SiGe BiCMOS technology. Two fractional-N phase-locked loops are used to generate dedicated frequency ramps for the transmitter and receiver and frequency shift keying for the transmitter. The signal-to-noise ratio (SNR) for the absorption line of gaseous methanol (CH 3 OH) at 247.6 GHz is used as measure for the performance of the system. The implemented mixer-first receiver allows a high performance of the system due to its linearity up to an input power of -10 dBm. Using a transmitter-array with an output power of 7 dBm an SNR of 4660 (integration time of 2 ms for each data point) was obtained for the 247.6 GHz absorption line of CH 3 OH at 5 Pa. We have extended our single frequency-band system for 228 - 252 GHz to a 2-band system to cover the range 222 - 270 GHz by combining corresponding two transmitters and receivers with the frequency bands 222 - 256 GHz and 250 - 270 GHz on single transmitter- and receiver-chips. This 2-band operation allows a parallel spectra acquisition and therefore a high flexibility of data acquisition for the two frequency-bands. The 50 GHz bandwidth allows for highly specific and selective gas sensing. © 2019 Author(s).

2007, Osmany, S.A., Herzel, F., Schmalz, K., Winkler, W.

We present an analytical phase noise model for fractional-N phase-locked loops (PLL) with emphasis on integrated RF synthesizers in the GHz range. The noise of the crystal reference, the voltage-controlled oscillator (VCO), the loop filter, the charge pump, and the sigma-delta modulator (SDM) is filtered by the PLL operation. We express the rms phase error (jitter) in terms of phase noise of the reference, the VCO phase noise and the third-order loop filter parameters. In addition, we consider OFDM systems, where the PLL phase noise is reduced by digital signal processing after down-conversion of the RF signal to baseband. The rms phase error is discussed as a function of the loop parameters. Our model drastically simplifies the noise optimization of the PLL loop dynamics.