This work presents a fully integrated active quasi-circulator module including a power amplifier and a low noise amplifier for use in communication transceivers sharing the same antenna for transmission and reception. The circuit also includes a radio frequency power rectifier to recycle the power intrinsically lost in the divider/combiner type architecture. The proposed circuit was analyzed and evaluated in 130 nm CMOS technology at 2.45 GHz. Simulation results show that isolation between transmitter and receiver was kept above 30 dB in a frequency range from 2.41 GHz to 2.5 GHz and equal to 54 dB at the design frequency of 2.45 GHz. The return losses at all ports were below 11.8 dB, the insertion gains of the transmission and reception paths were over 3.2 dB and 6.9 dB, respectively. The noise figure in the reception path was less than 7.8 dB.

A Cartesian approach reflection coefficient measurement block based on a directional coupler and four quadrature mixers is presented in this work. The block was designed for use in an automatic impedance matching system in the ultra-high frequency range. Simulations, including parasitics, resulted in an average error of 3.4% full-scale and indicate a high potential of the approach for an implementation in integrated circuit technology. Measurements on a discrete setup demonstrate a maximum error of 28% full-scale and prove the usefulness of the approach.

Optically detected magnetic resonance (ODMR) of nitrogen-vacancy centers in diamonds, in addition to optical excitation with green light, requires microwave excitation and thus a microwave structure. While many different microwave structures including microwave resonators have been presented in the past, none of them fulfilled the need to fit inside the miniaturized quantum magnetometer with limited space used in this work. This is why a novel microwave resonator design using commercially available printed circuit board technology is proposed. It is demonstrated that this design is of small form factor, highly power efficient and low-cost, with very good reproducibility, and in addition, it can be fabricated as a flexible printed circuit board to be bent and thus fit into the miniaturized sensor used in this work. The design choices made for the resonator and the way in which it was trimmed and optimized geometrically are presented and ODMR spectra made with a miniaturized quantum sensor in combination with such a resonator, which was fed by a microwave generator set to different microwave powers, are shown. These measurements revealed that a microwave power of −4 dBm is sufficient to excite the m_s = ±1 states of the nitrogen-vacancy centers, while exceeding −1 dBm already introduces sidebands in the ODMR spectrum. This underlines the efficiency of the resonator in exciting the nitrogen-vacancies of the diamond in the sensor platform used and can lead to development of low-power quantum sensors in the future.

For the development of a novel optical sensor technology, diffraction grating microstructures were manufactured on a silicon surface. The principle of operation of the sensor technology is based on rotatory encoder technology, developed at Hahn-Schickard. It is based on a convolution of a Gaussian laser beam at a diffraction grating, generating sine and cosine signals resulting from the movement of the diffraction grating. Applying this approach to silicon is new and places technological challenges, which are overcome using a proprietary nanoimprint lithography (NIL) process. The process development, which was done on bulk silicon, is discussed, and its capability of producing operational optical grating microstructures is verified by moving the bulk silicon chips with the grating over an opto-electronic module using a piezo stage in an automated control and data acquisition setup. The noise measured in a 16-bit setup was below 2.8 nm RMS, and the linearity error was 100 nm RMS. Compared to the traveled distance (320 µm), this is less than 350 ppm. Furthermore, the chips with the grating were refined to a MEMS-accelerometer chip by introducing etched spring structures. This setup then was verified using different miniaturized interpolator boards.