Diego Vázquez

Practical oscillation-based test of integrated filters

Oscillation-based test (OBT) techniques show promise in detecting faults in mixed-signal circuits and require little modification. to the circuit under test. Comparing both the oscillations amplitude and frequency yields acceptable test quality. OBT seems especially appealing for filters but requires adaptation to handle monolithic circuits or the analog-core-based design of complex mixed-signal ICs.

Effective oscillation-based test for application to a DTMF filter bank

This paper deals with a case study applying oscillation-based testing to an industrial circuit. The aim of the presentation is to discuss a practical way of carrying out an effective implementation of the oscillation test technique as well as discussing guidelines for its application.

Testing mixed-signal cores: a practical oscillation-based test in an analog macrocell

A formal set of design decisions can aid in using oscillation-based test (OBT) for analog subsystems in SoCs. The goal is to offer designers testing options that do not have significant area overhead, performance degradation, or test time. This work shows that OBT is a potential candidate for IP providers to use in combination with functional test techniques. We have shown how to modify the basic concept of OBT to come up with a practical method. Using our approach, designers can use OBT to pave the way for future developments in SoC testing, and it is simple to extend this idea to BIST.

Testable switched-capacitor filters

A Design for Test methodology for S-C filters is presented, based on an architecture using some additional circuitry and providing extra capabilities for both off-and on-line test. The approach uses a comparison mechanism to indicate whether or not two copies of a filter element (a biquad, for instance) have a similar response during their actual operation. The design and implementation of an integrated filter is included to assess the potential usefulness of this new approach.

A new strategy for testing analog filters

A new strategy for testing analog filters is presented, based on the reevaluation of the transfer function followed by simple processing of the output signals. Taking advantage of the structural properties of some universal biquads, this new strategy consists in provoking pole-zero cancellation during the test mode, without eliminating information about parameters which determine the normal circuit operation. Although area overhead could seem high, it can be very small in many applications.<<ETX>>

Improving the testability of switched-capacitor filters

A design-for-test methodology for SC filters is presented, based on an architecture using some additional circuitry and providing extra capabilities for both off-and on-line tests. The approach uses a comparison (voting) mechanism to indicate whether or not two copies of a filter element (a biquad, for instance) have a similar response during their actual operation. The design and implementation of a few filter examples are included to assess the potential usefulness of this new approach.

A high-Q bandpass fully differential SC filter with enhanced testability

This work describes a 6th order high-Q Bandpass SC filter which has been designed to prove the feasibility of a unified on- and off-line testing approach. Several design issues to reduce the impact of extra circuitry in the performace, area and power dissipation overhead are discussed, and experimental results from a prototype are presented.

On-Chip Evaluation of Oscillation-Based-Test Output Signals for Switched-Capacitor Circuits

This work presents a simple and low-cost method for on-chip evaluation of test signals coming from the application of the Oscillation-Based-Test (OBT) technique. This method extracts the main test signal features (amplitude, frequency and DC level) in the digital domain requiring just a very simple and robust circuitry. Experimental results obtained from an integrated chip demonstrate the feasibility of the approach.

A solution for the on-line test of analog ladder filters

In this paper we study stability problems associated with the previously developed design for test (DFT) methodology applied to ladder filters. A solution based on simple modification of the basic DFT strategy is proposed which allows on-line testing of ladder filters. A filter example demonstrates the feasibility of the solution.

On-Chip Analog Sinewave Generator with Reduced Circuitry Resources

This paper proposes an analog sinewave signal generator with minimal circuitry resources. It is based on a linear time variant filter that gives a high quality sine signal in response to a DC input. The proposed architecture has the attributes of digital programming and control capability, robustness and reduced area overhead, what make it suitable for BIST applications. Experimental results from a practical design demonstrate the feasibility of the approach.