Giovanni Chiorboli

ADC sinewave histogram testing with quasi-coherent sampling

In this paper the accuracy of sinewave histogram testing is analyzed under the assumption of quasi-coherent sampling. It is proved that same worst-case results are obtained as already published ones, by allowing a bound on the accuracy in setting the ratio between sinewave and sampling frequencies, which is looser than that currently employed. Detailed proofs and simulation results are presented.

A new method for estimating the aperture uncertainty of A/D converters

Aperture uncertainty measurements are strongly influenced by quantization, converter nonlinearity and test setup noise. The proposed method solves the difficulties arising from quantization, and nonlinearity. The method estimates the noise distribution function by fine adjustment of the input signal offset. The contribution of jitter-induced voltage noise is separated from additive noise in two different ways. Finally, the aperture uncertainty, assumed independent of the frequency, is estimated by varying the signal frequency. Experimental results obtained on 8 and 10 bit converters are discussed.

Design and characterization of magnetostrictive linear displacement sensors

The design of a low-cost, linear position sensor, based on the transmission of ultrasonic signals in a magnetostrictive delay line is presented. The paper analyzes the sensor principle, parameters to be optimized, conditioning circuits as well as sensor characterization, comparing the results with commercial sensors.

Analysis of distortion in A/D converters by time-domain and code-density techniques

Two new methods for measuring the total harmonic distortion of an A/D converter are described. One is based on time-domain analysis, the other on modified code density analysis. Experiments show that these methods give results comparable to the ones provided by FFT analysis. It is then shown, by both experiments on a flash converter and computer simulations, that the conventional code density analysis does not provide accurate signal-to-noise-plus-distortion ratio (SNDR) estimates at the highest frequencies, while the proposed methods do.

Integrated lock-in amplifier for contactless interface to magnetically stimulated mechanical resonators

The design of an integrated lock-in amplifier is discussed, specifically conceived for the detection of low-level signals at a harmonic of the drive frequency in magnetically excited resonant structures. The circuit includes in-phase and quadrature analogue signal processing channels, whose outputs feed an integrated SigmaDelta analogue to digital converter. The circuit can be operated in different configurations, depending on the application requirements: in particular, by combining the digitized outputs of the two channels, vector operation can be obtained. The entire analogue chain, including the SigmaDelta modulator, was designed using fully differential elaboration. The circuit was developed in a 0.35 mum, dual poly-Si, four metal layers analogue CMOS technology with high resistivity poly-Si option. Performance based on transistor-level simulations are provided.

About the number of records to be acquired for histogram testing of A/D converters using synchronous sinewave and clock generators

Abstract The number of records and samples to be acquired for the measurement of INL or DNL was determined in [J. Blair, Histogram measurement of ADC nonlinearities, IEEE Transactions on Instrumentation and Measurement, 43, June 1994, 373–383.] as a function of the desired test tolerance and confidence level. In the present work, that analysis is reconsidered, to show that a slightly more conservative formulation is advisable, taking into account effects neglected in the original work.

Sub-picosecond aperture-uncertainty measurements [ADCs]

Sub-picosecond aperture uncertainty measurement is nowadays a challenge in the test of state-of-the-art high-speed high-resolution A/D converters. This work describes the existing techniques and analyzes the limits in the measurement accuracy obtainable with the double-channel techniques and the instrumentation available today. Preliminary experiment results are provided.

Cross-correlation noise measurements in A/D converters

This is the second paper of a series describing theories and experiments of a new analysis technique able to accurately characterize the time-varying noise of A/D converters (ADC). In the previous work, the effects of the quantization and nonlinearities on the jitter measurement were considered, and an efficient solution to this problem was demonstrated. This paper presents a dual channel measurement technique that is still independent of quantization and nonlinearities, and that allows one to separate from the ADC noise the noise contribution of the test setup. The method, based on the measurement of the cross-correlated noise between the two channels, provides more accurate measurements of the ADC noise than may be possible with traditional test equipment.

Test structures for dielectric spectroscopy of thin films at microwave frequencies

This work describes the application of two different test structures to execute broadband microwave measurements of the dielectric constant of ceramic thin films. Coplanar waveguide probes and vector network analyzer were used to measure the dielectric constant versus frequency of thin films of lead zirconate titanate and zirconium titanate, fabricated by sol gel methods. One-step lithography was used to produce planar metal-insulator-metal and interdigitated capacitor test patterns. The two test structures are compared for zirconium titanate films. The metal-insulator-metal method has been applied also to a lead zirconate titanate film and to show the capability of computing the dielectric tunability.

Test and diagnosis of subranging A/D converters

A test methodology for linear modeling of subranging analog-to-digital converters with digital correction is proposed. A reduced physical model of integral nonlinearity errors is obtained by the application of the ambiguity algorithm. Simulation results are provided which demonstrate that a sensible reduction of the number of test points can be obtained, thus reducing the high costs of testing, with low prediction errors.