Good High Frequency Performance Research Articles

Concentration and temperature dependent selectivity of the LTCC porosification process with phosphoric acid

The wireless high frequency (HF) technology requires a robust, well-established and cost-effective substrate solution with a tailored permittivity. The wet-chemical porosification of low temperature co-fired ceramics provides such a substrate by locally embedding air into the surface. The present study investigates the relation of air embedment and surface alteration in detail, utilizing gravimetric methods as well as scanning electron microscopy with and without focused ion beam technology. The porosification approach could successfully be transferred from the DuPont 951, which features a high selectivity, to Heraeus CT 702 with good HF performance. By applying ring-resonator based permittivity measurements, a similar permittivity reduction by approx. 10% at a maximum frequency of 70GHz could be confirmed. The optimum etch parameters for an LTCC allowing a further metallization are a phosphoric acid mass fraction of 50wt%, a temperature of 100°C at maximum and a minimum treatment time of 8h.

Electronically Tunable Sinusoidal Oscillator Circuit

This paper presents a novel electronically tunable third-order sinusoidal oscillator synthesized from a simple topology, employing current-mode blocks. The circuit is realized using the active element: Current Controlled Conveyors (CCCIIs) and grounded passive components. The new circuit enjoys the advantages of noninteractive electronically tunable frequency of oscillation, use of grounded passive components, and the simultaneous availability of three sinusoidal voltage outputs. Bias current generation scheme is given for the active elements used. The circuit exhibits good high frequency performance. Nonideal and parasitic study has also been carried out. Wide range frequency tuning is shown with the bias current. The proposed theory is verified through extensive PSPICE simulations using 0.25 μm CMOS process parameters.

The Multi-Point Initiation Technology Based on Piezoelectric High-Voltage Converter of an Electronic Security System

The multi-point initiation control technology of electronic security systems uses high-performance and high-pressure transformer, which gains efficient multiple high-pressure slapper ignition energy. Because of its small size, light weight, good high frequency performance characteristics of electronic security systems for the high-voltage transformation circuit, piezoelectric transformer provides a new solution. Firstly, the structure and working principle of electronic security systems based on piezoelectric pressure converter is discussed in this paper. By analyzing the high-voltage converter output circuit of the equivalent load of converter, the frequency characteristics of the charging process for the piezoelectric-driven frequency high-voltage converter is designed in theory. To improve the efficiency of its high-voltage charge, control circuits such as quantum-based control mode design is presented. At last, high-voltage converter of piezoelectric multi-point initiation of electronic security systems technology is given here.

High Frequency Performance of SiGeC HBTs with Selectively & Non-Selectively Grown Collector

Two high-frequency heterojunction bipolar transistor (HBT) architectures based on SiGeC have been fabricated and characterized. Different collector designs were applied either by using selective epitaxial growth doped with phosphorous or by nonselective epitaxial growth doped with arsenic. Both designs have a nonselectively deposited SiGeC base doped with boron and a poly-crystalline emitter doped with phosphorous. Both HBT designs exhibit similar electrical characteristics with a peak DC current gain of around 1600 and a BVCEO of 1.8V. The cut-off frequency (fT) and maximum frequency of oscillation (fmax) vary from 40–80GHz and 15–30GHz, respectively, depending on lateral design relations. Good high frequency performance for a device with a selectively grown collector is demonstrated for the first time.

InP-HBTs with good high frequency performance at low collector currents using silicon nitride planarisation

A fabrication process for small area HBTs with a self-aligned base contact has been developed, based on silicon nitride planarisation. The mean current gain for 130 realised devices ranged from 40 for the smallest devices, to 71 for the largest, with a standard deviation of <10%. The transit frequency was 94.7 ± 2.6 GHz, and the maximum frequency of oscillation 95.1 ± 4.4 GHz, at a collector current of only 0.3 mA. The extremely good high frequency performance at low currents and high uniformity improves the competitiveness using InP-based HBTs for fabrication of complex integrated circuits.

High frequency measurement of multilayer ceramic capacitors

The monolithic ceramic capacitor (MLC) is small and has good high frequency performance. It is used in various high frequency circuits for impedance matching, DC block, filter and bypass functions. For the best performance in these applications, low equivalent series resistance (ESR) and equivalent series inductance (ESL) is required. We have developed the testing method to compare the performance of different MLC designs to find out the effect on the ESR and ESL. In order to measure the high frequency performance accurately, we have developed a test fixture using the microstrip design. The fixture has a return loss of greater than 30 dB and the insertion loss is less than 0.5 dB. The MLC is mounted on the microstrip fixture and the return loss (RL) and the insertion loss (IL) is measured. A network analyzer is used to compensate for the fixture to obtain good data up to 15 GHz. Using this method, we compare two designs for microwave power applications and two designs for high speed digital applications. We have developed the ultra small capacitor that has good performance in high speed digital circuits.

50 GHz Si 1 − xGe x heterobipolar transistor: growth of the complete layer sequence by molecular beam epitaxy

The six-layer structure of a Si 1 − x Ge x heterobipolar transistor (HBT) with flat doping levels and abrupt junctions is grown by a silicon molecular beam epitaxy (MBE) process in one run. The process, the MBE equipment used and analytical results (secondary-ion mass spectrometry) are described. The growth temperature is reduced from 650 °C at the collector to 325 °C at the emitter contact. A Si 1 − x Ge x base doping level of 5 × 10 19 cm −3 is obtained by coevaporation of silicon, germanium and boron from an electron beam evaporator, a BN effusion cell and a high temperature graphite cell respectively. The n-type doping of 10 16–10 20 cm −3 (collector, emitter and emitter contact) is obtained by applying three different antimony dopant incorporation methods. Test transistors fabricated from these structures exhibited low noise, good high frequency performance ( f T, f max > 50 GHz) and low base sheet resistance (less than 1 kΩ/□).

High frequency gallium arsenide current mirror

A new negative current mirror using n-channel GaAs MESFETs is proposed. The circuit combines the advantages of linearity and good high frequency performance. Applications are as a general high speed circuit building block and for high frequency amplification.