The design of mixed-signal ASICs for space requires a detailed knowledge of the behaviour of the technology to be used in an environment imposing radiation levels and temperatures beyond those found in standard applications. Commercial foundries providing standard CMOS technologies do not usually have or make available data on the behaviour of their devices under those conditions. Instituto de Microelectrónica de Sevilla and Universidad de Sevilla (IMSE-USE) have started a long term collaboration with the Spanish Instituto Nacional de Técnica Aeroespacial (INTA) to extend its experience on mixed-signal design to the field of ASICs for space applications. The assessment of a commercial (austriamicrosystems) 0.35µm CMOS technology is a first step towards the development of a mixed-signal design methodology, including the development of an RHBD digital library suitable for use in space conditions.
We present a very-large-scale integration continuous-time sinusoidal operational transconductance amplifiers quadrature oscillator fabricated in a standard double-poly 0.8-m CMOS process. The oscillator is tunable in the frequency range from 50 to 130 MHz. The two phases produced by the oscillator show a low-quadrature phase error. A novel current-mode amplitude control scheme is developed that allows for very small amplitudes. Stability of the amplitude control loop is studied as well as design considerations for its optimization. Experimental results are provided.
Index Terms-Amplitude control, analog very large-scale integration (VLSI),, impedance probe, multiphase oscillators, operational transconductance amplifiers (OTA)-C, oscillator stability, phase noise, quadrature oscillators, sinusoidal oscillators, transconductance-capacitance oscillators.
A computer-controlled system for measuring M-H hysteresis loops of soft magnetic materials is described. It overcomes many of the problems associated with these kinds of measurements of low coercivity materials. The combination of ‘‘low drift’’ hardware and measurement procedure makes software correction unnecessary. At every field step, the homemade integrator is reset in order to minimize the drift and to provide a way of separating the sample contribution to the signal from the field contribution and, consequently, to allow M-H plots. Furthermore, to avoid the residual drift of the hardware, the method of ‘‘two-way measurement’’ is applied, giving drifts of 0.01% per hour. Results obtained for a FINEMET alloy film annealed at different temperatures are presented, illustrating the ability of the system to measure soft magnetic materials.
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