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Charge pump design in 130 nm SiGe BiCMOS technology for low-noise fractional-N PLLs
2015, Kucharski, M., Herzel, F.
This paper presents a numerical comparison of charge pumps (CP) designed for a high linearity and a low noise to be used in a fractional-N phase-locked loop (PLL). We consider a PLL architecture, where two parallel CPs with DC offset are used. The CP for VCO fine tuning is biased at the output to keep the VCO gain constant. For this specific architecture, only one transistor per CP is relevant for phase detector linearity. This can be an nMOSFET, a pMOSFET or a SiGe HBT, depending on the design. The HBT-based CP shows the highest linearity, whereas all charge pumps show similar device noise. An internal supply regulator with low intrinsic device noise is included in the design optimization.
Transmitters and receivers in SiGe BiCMOS technology for sensitive gas spectroscopy at 222 - 270 GHz
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).