Resonant diaphragm pressure measurement system with ZnO on Si excitation

The principle of measuring pressure by means of a resonant diaphragm has been studied. An oscillator consisting of an integrated amplifier with a piezoelectrically driven diaphragm in its feedback loop has been built. The oscillator frequency is accurately proportional to the square of the pressure in the range of 60 to 130 Torr.\ud The frequency range is 1324 to 1336 Hz (this range being limited by a spurious mode which could be suppressed by better processing) for a 25 mm diameter diaphragm made of a silicon wafer and with PZT ceramics as driver and receptor. We have made an integrated version (1 × 1 mm2) of a square resonant diaphragm pressure guage by selective etching of (1 0 0) planes with ethylenediamine. The piezoelectric driving materials was sputtered zinc oxide. A driver was deposited midway between the bending point and the point of greatest curvature.\ud A receptor was located at a symmetrical position to give a optimum transfer condition.\ud The integrated current amplifier had a low impedance differential input stage, two gain cells and a high impedance output stage. These electrical conditions ensured maximum elastic freedom of the diaphragm. A digital circuit in I2L technology has been designed and made with eight-bit parallel read out of the frequency. This circuit may be directly connected to a microprocessor. The whole system contains the sensor chip, the analog amplifier chip and the digital chip, all in compatible technology.\ud \u

0-Level packaging techniques for flip-chip mounted MMICs

Currently, the thin film microwave multi-chip module (MCM) technology offers many benefits for a compact, lightweight and low cost integration of RF and microwave circuits [see Carchon et al (1)]. This technology allows the realisation of low loss transmission lines with a variety of characteristic impedances (between 10 and 100 Ohm) up to the higher mm-wave frequencies (>50 GHz). The technology also allows mounting active circuits (such as MMICs) by e.g. flip-chip technology. However, when placing different functions closely together, an adequate shielding and also mechanical protection of the active dies may be required. For this purpose, we developed a wafer level (called 0- level) package concept using micromachined cavities to realise versatile, microwave compatible protection and shielding structures on the thin film substrate. 0-level packaging refers to packaging before separation of the dies of the thin film integration substrate. In order to illustrate this concept and the benefits in real microwave functions, the realisation of a Ka-band LNA module, including 0-level package, bias circuits and RF feedthrough structures is discussed in this contribution

Microwave applications of advanced semiconductor technologies

New semiconductor technologies, used in passive microwave applications, allow the integration of passives with high quality factors and the fabrication of novel RFMEMS components for switches and tunable capacitors and resonators. The use of these technologies results in a strong reduction of the size and the power consumption of wearable microwave systems. The scaling of silicon transistors, following Moore’s law, results in RF-CMOS devices approaching the performance of III-V and SiGe devices but at a considerably lower cost and much higher integration capability. The introduction of GaN based technologies offering new possibilities in the field of power microwave devices is discussed

Use of RF MEMS and micromachined parts to realize highly integrated V band active feed for satellite antennas

International audienc