Keiko Makie-Fukuda

Voltage-comparator-based measurement of equivalently sampled substrate noise waveforms in mixed-signal integrated circuits

This paper describes measurement of substrate noise waveforms in mixed-signal integrated circuits. This method uses wide-band chopper-type single-ended voltage comparators as on-chip noise detectors. By analyzing equivalently sampled comparator outputs in synchronized operation, the noise voltage in the auto-zero and compare modes can be measured separately, and noise waveforms were experimentally reconstructed to within 0.5-ns accuracy. The noise transmission path was analyzed, and this showed that the noise sampled at the auto-zero mode of the comparator can be used to reconstruct substrate noise waveforms with high resolution. The results also explain the influence of noise coupling on analog circuits widely used in on-chip analog-to-digital converters.

Measurement of digital noise in mixed-signal integrated circuits

This paper proposes a method of measuring the influence of digital noise on analog circuits using wide-band voltage comparators as noise detectors. Noise amplitude and r.m.s voltage are successfully measured by this method. A test chip is fabricated to measure the digital noise influence. From the experimental results, it is shown that the digital noise influence can be considerably reduced by using a differential configuration in analog circuits for mixed-signal ICs. The digital noise influence can be further reduced by lowering the digital supply voltage. These results show that the voltage-comparator-based measuring method is effective in measuring the influence of digital noise on analog circuits. >

On-chip active guard band filters to suppress substrate-coupling noise in analog and digital mixed-signal integrated circuits

An AC coupling configuration of active guard band filters can supply a substrate-coupling-noise cancellation signal to a ground-level substrate by using a single 3 V supply to on-chip circuits. Noise was suppressed to a maximum of less than 0.05 from 100 Hz to 2 MHz in a 0.35 /spl mu/m CMOS test chip. Experiments and a simulation based on the substrate model showed that the noise-suppression effect depends on the guard-band arrangement. The simulation is thus effective for optimizing the arrangement to strongly suppress noise effects.

Substrate noise measurement by using noise-selective voltage comparators in analog and digital mixed-signal integrated circuits

In mixed-signal ICs, substrate noise produced by high-speed digital circuits passes to the on-chip analog circuits through the substrate and seriously affects their performance. In this paper, we discuss how the substrate noise can be measured by using noise-selective chopper-type voltage comparators as noise detectors to detect the wide-band substrate noise so as to analyze and further reduce its effect. A switched capacitor is selectively loaded to the inverter amplifier of the comparator during the comparison period to reduce the noise detection at the transition from compare to auto-zero. The noise at the transition from auto-zero to compare can be selectively detected. Waveforms of the high frequency substrate noise were reconstructed by this on-chip noise detector incorporating the noise-selective comparators implemented using a 0.5-/spl mu/m CMOS bulk process.

High-speed measuring system for testing mixed-signal-LSI performance and its application to digital-noise measurement

An automatic measuring system is developed for laboratory use for performance testing and design verification of analog and mixed-signal LSIs. Through the high-speed circuit and board design techniques, an 8-bit 1 GHz arbitrary waveform generator (AWG) and 3 GHz sampling waveform digitizer (SWD) were implemented in the system. This enables the range for measuring high-frequency mixed-signal-LSI performance to be extended from MHz up to GHz. A statistical digital-noise measurement method is presented as an application of the system. The digital-noise performance is automatically analyzed on the system by measuring and processing the statistical output results of the on-chip analog comparators operating on a mixed-signal LSI in order to detect the digital-noise coupling.<<ETX>>

Voltage-comparator-based measurement of equivalently sampled substrate noise waveform in mixed-signal integrated circuits

A method is proposed for measuring substrate noise waveforms in mixed-signal integrated circuits. This method uses wideband chopper-type single-ended voltage comparators as on-chip noise detectors. By analyzing the equivalently sampled comparator outputs from synchronized operation, the noise voltages in auto-zero and compare modes can be separately detected and the noise waveforms can be reconstructed within 2-nsec accuracy. The measured results also explain the influence of noise coupling on analog circuits widely used in on-chip analog to digital converters.