PhD Defense of Walid AOUIMEUR

Microelectronic applications such as wireless communications, radar or space detections require higher data rate resolutions, implying the use of millimeter wave and submillimeter frequencies. Thanks to the silicon technologies improvement, some microelectronic circuits are emerging working in the frequency range of 140-220 GHz (G-band) but they suffer from a lack of complete characterization tools involving costly investment. For example, there is currently no commercial vectorial network analyser (VNA) that can measure S parameters in the 4-ports G-band.
The classical characterization of millimeter wave circuits in n ports (with n> 2) consists in using a vectorial analyzer of 2-ports networks and matching the other unused ports to 50Ω. By circular permutation, one thus manages to extract the S matrix from a device with n ports (with n> 2). This set up induces very long and difficult measurements and it requires on the one hand some very expensive measuring equipment at millimeter frequencies and on the other hand to implement accurate and dedicated calibration and de-embedding methods.
Therefore, the work developed into this PhD study aimed to integrate in the die the measurement systems that would measure small signals "S-parameters" of the device under test (DUT). Being closer to the DST makes it possible to reduce the insertion losses, to reduce the amplitude of the error vectors and thus the residual errors after calibration. Moreover, it is possible to better control the power of the signal sent and to consider calibration methods using integrated loads, which reduces the time and cost processing. The technology used is the SiGe BiCMOS 55 nm technology developed by STMicroelectronics, a technology dedicated to RF and millimeter wave’s circuits.
The system developed is a 1-port system. The solution developed consists on connecting the wafer with some probes and driving it with an external signal that spans the 35-55 GHz band. Once into the die, this signal is then quadrupled in frequency and amplified to reach good power level in G band at the DUT inputs. Some S-parameters (S11 and S22) are extracted from the DUT thanks to some very directive couplers designed respectively at the input and at the output of the DUT.  The outputs of the couplers are then converted to low frequencies (IF =0.5-2.4 GHz) through passive frequency mixers.
In a first part of the thesis manuscript, the way to work is argued, supported by a study of the state of the art concerning the measurement systems. Then, design and characterization of each blocks of the system are detailed: the frequency quadrupler in G band (composed of a W band frequency doubler, followed with a G band frequency doubler), the fully integrated transfer switch in G-band allowing driving the millimeter waves signal to the DUT input or to the DUT output, the directive couplers based on the slow wave lines, the frequency mixers used to bring back the results in base band frequency, etc… All the different blocks detailed, the measurement systems can be introduced. A first system, a one-port measurement system, has been designed as a proof of concept. Once the approach validated, a second system, two-port measurement system, has been developed presenting a heterodyne architecture and a transfer switch in G band driving the input signal toward the DUT input or output.

Key words:
Built In Self Characterization, G Band, S-parameters, Frequency multiplier, Transfer switch, Coupler, Integrated tunable load, Mixer, SiGe BiCMOS 55 nm, Heterodyne.