Analog sinewave signal generators for mixed-signal built-in test applications

This work presents a technique for the generation of analog sinusoidal signals with high spectral quality and reduced circuitry resources. Two integrated demonstrators are presented to show the feasibility of the approach. The proposed generation technique is based on a modified analog filter that provides a sinusoidal output as the response to a DC input. It has the attributes of digital programming and control, low area overhead, and low design effort, which make this approach very suitable as test stimulus generator for built-in test applications. The demonstrators—a continuous-time generator and a discrete-time one—have been integrated in a standard 0.35 μm CMOS technology. Simulation results and experimental measurements in the lab are provided, and the obtained performance is compared to current state-of-the-art on-chip generation strategies.Gobierno de España TEC2007-68072/MIC, TSI-020400-2008-71/MEDEA+2A105, CATRENE CT302Junta de Andalucía P09-TIC-538

A new BIST scheme for low-power and high-resolution DAC testing

A BIST scheme for testing on chip DAC is presented in this paper. We discuss the generation of on chip testing stimuli and the measurement of digital signals with a narrow-band digital filter. We validate the scheme with software simulation and point out the possibility of ADC BIST with verified DACicus-journals

AD変換器テスト用信号発生技術の研究

修士論

Application of external customized waveforms to a commercial quadrupole ion trap

AbstractThe Finnigan LCQ quadrupole ion trap has recently become part of the repertoire of instruments for many analytical laboratories. The LCQ commercial design, while employing complex waveforms to manipulate ions, does not allow the application of many state-of-the-art user-defined waveforms that enable one to perform other complex ion manipulations. The work presented here describes the simple modifications made to the LCQ electronics to allow the application of external customized waveforms. Results show that externally generated waveforms can be applied to the endcap electrodes while still working within the context of the commercial software and hardware. Double resonance, multiple ion isolation, and multiple ion excitation experiments are demonstrated to reveal the effectiveness of these modifications

A Goertzel Filter Based System for Fast Simultaneous Multi-Frequency EIS

Bioimpedance measurement is a non-invasive, radiation-free, and inexpensive method for measuring the electrical properties of biological tissues. In applications where transients occur, the commonly used swept sinewave is replaced with broadband signals such as multisine. This makes the signal generation and the extraction of the real and imaginary parts of the impedance challenging. In this brief, an alternative to traditional fast Fourier transform (FFT) or coherent demodulation is presented. Based on the Goertzel filter, this alternative is simpler and requires very few digital resources. Its robustness to the harmonic fold back phenomenon, enables simple ternary current pulses to be used for excitation. The developed digital architecture is capable of simultaneous demodulation of 16 frequencies with an accuracy of 97% and 96% on the magnitude and phase measurement respectively. Employing a ternary sequence allows the use of a low power H-bridge current driver. The analog front-end and demodulation algorithm were implemented in an ASIC using a 180-nm CMOS technology. The system was tested on an isolated pig heart distinguishing edema from non-edema tissue by impedance changes

ADC standard IEC 60748-4-3: precision measurement of alternative ENOB without a sine wave

A practical analog-to-digital converter (ADC) introduces quantization error in excess of the ideal value and one way of expressing this is by comparing the value of this error with that of an ideal ADC. This comparison is known as the effective number of bits (ENOBs). It is accepted practice to measure ENOB using the signal-to-noise and distortion (SINAD) ratio of a sine-wave input. This paper extends ENOB theory to any arbitrary waveform by including the crest factor of the input signal. It is now possible to apply the ENOB concept to wideband systems. Measuring the SINAD of an arbitrary or multitone waveform with precision normally requires the use of laboratory standard test equipment. However, International Electrotechnical Commission standard 60748-4-3 specifies an alternative method for wideband SINAD measurements that may also be suitable for built-in test. It is essentially a multitone test using two pseudorandom signal sources and is sometimes known as the double comb-filter (DCF) method. This paper demonstrates the requirements for a practical implementation of a DCF-based system for measuring an ENOB of up to 24 bits. It is shown that in a practical application, DCF ENOB and sine-wave ENOB results have similar levels of accuracy, but in the presence of amplitude nonlinearity the differing test signal amplitude weightings cannot fundamentally produce the same ENOB figure. It is shown that DCF ENOB is more representative of communications system performance and therefore extends the use of ENOB to wideband application

Development of instrumentation incorporating solid state gas sensors for measurement of oxygen partial pressure.

Electronic instrumentation was developed for the measurement of the oxygen partial pressure, P1 ( in a sample gas using fully-sealed zirconia pump-gauge oxygen sensors operated in an AC mode. These sensors, operated typically at 700°C, consisted of two discs of zirconia with porous platinum electrodes on each face separated by a gold seal and enclosing a small internal volume. One disc was operated as a pump enabling oxygen to be electrochemically transferred into and out of the enclosed volume; the other disc operated as a gauge, the Nernst EMF across the electrodes providing a measure of the ratio of the internal to the external oxygen partial pressure. By careful design of the circuitry it was possible to measure the oxygen partial pressure, P, without the need for a separate reference gas supply. Subsequently, a novel "tracking" mode of operation was proposed and implemented in which leakage effects generally associated with sealed pump-gauge devices were minimised: the sensor was operated in a feedback control-loop in order to adjust automatically the mean internal reference oxygen partial pressure, P0, so as to maintain the ratio (Px/P0) close to unity. The signal-to-noise ratio was markedly improved by using gauge EMFs with high amplitudes which inevitably display a distorted sinusoid due to the logarithmic term in the Nernst equation. Surprisingly, mathematical analysis predicted that the linearity of the output of the instrument using phase-sensitive detection should not be affected by the deviation from a sinusoid and this was confirmed experimentally: signal processing was practically implemented using simple analogue electronics. As anticipated there was a strong influence of sensor temperature on the output of the instrument: consequently, methods for temperature compensation were proposed and shown to be feasible with minimum hardware. The theory of Operation of leaky pump-gauge was also developed which indicated that a physical leak in the sensor should cause a phase shift and amplitude change in the sensor output. Experimental results were, in general, in agreement with the theory demonstrating the influences of the geometry and dimensions of the leak and of the operating frequency. Importantly, the theory predicted that, when operated in the AC mode, devices with major leakage may still be used for oxygen partial pressure measurement: again this was confirmed by experiment and the additional benefit of a concomitant substantial simplification of the electronic circuitry also realised. Interestingly an unexpected but small influence of oxygen concentration on the phase shift was observed: this requires additional study

Sound Synthesis Using Programmable System-On-Chip Devices

The last 20 years has witnessed a resurgence of interest in analogue synthesisers 1 . Manufacturers, such as Moog and Sequential Circuits, that had disappeared from the commercial marketplace by the end of the 1980’s, have reappeared with an impressive line of products. Other established companies such as Korg and Roland, as well as entrants that had made their name with digital technology, such as Novation and Arturia, have released analogue instruments. Although the feature set of digital synthesisers is extensive and with a falling comparative cost, the analogue market has continued to grow with more and more devices coming available. They are perceived to be of superior sound quality by users, but their primary drawback is price, as numerous discrete components or specialist integrated circuits are required. This thesis introduces two novel low-cost approaches to building analogue-type synthesisers. Such a low-cost instrument could have applications in an educational laboratory environment for synthesisers. The first approach is to exploit a new mixed-signal technology called the Programmable System-on-Chip (PSoC), which includes a CPU core and mixed-signal arrays of configurable integrated analogue and digital peripherals. The second exploits a System on Chip (SoC) comprising an ARM-based (Acorn RISC Machine) processor and a Field-Programmable Gate Array (FPGA). Two synthesisers were built and were evaluated for difficulty of implementation and assessed for their sound quality. The design and testing process was recorded and documented in detail. The mixed-signal approach was found to be cheaper than the FPGA-approach both in terms of component costs and development time compared to the FPGA-based approach. Actually, the FPGA-approach was determined to be prohibitively expensive in terms of the development time incurred. The sound quality analysis demonstrated that both instruments were perceived by users to be of high quality, achieving a noticeable analogue sound. Future work would be to repackage the PSoC system and modules into rack-mounted form for use in an educational synthesiser laboratory environment