Abstract: The phase relation of clock signals to be applied to an interleave type analog-to-digital conversion apparatus having N analog-to-digital converters is calibrated by applying a repetitive reference signal to the N analog-to-digital converters. The digital values from the N analog-to-digital converters are selected at corresponding sampling points of successive cycles of the reference signal. The clock phase relation is adjusted such that the selected digital values are made substantially equal to each other.

Abstract: A logic analyzer is disclosed which displays at least an input logic signal on a cathode ray tube, controls a cursor position on the cathode ray tube and obtains a relationship between a predetermined phenomenon included in the input logic signal and the cursor position. In a search mode, the predetermined phenomenon is a search word or a glitch. In a compare mode, the predetermined phenomenon is a reference logic signal.

Abstract: An amplitude limiter circuit is provided in which the output terminal is disconnected from the input terminal, or the input signal source, when the input signal amplitude exceeds the predetermined upper and/or lower limit. Voltage maintenance means maintains the output voltage when the amplitude limiting condition is reached.

Abstract: A calibration apparatus for analog-to-digital converter or transient recorder including both analog and digital sections is disclosed. A built-in calibrator automatically calibrates the gain and DC level of the entire system to substantially the same accuracy as that of the digital section, thereby avoiding relatively large errors of the analog section. The amplitude or gain calibration is always performed over the full range of the digitizer used in the digital section.

Abstract: A high speed analog-to-digital conversion method and apparatus including a plurality of parallel analog-to-digital converters is disclosed. A clock signal is applied to each of the analog-to-digital converters at different phase relation to increase the equivalent sampling frequency by multiplexing the outputs into a serial form. A reference signal such as a linear ramp or sawtooth signal is used to maintain the correct phase relation, thereby eliminating any errors due to differences in electrical characteristics among the analog-to-digital converters. Such correction may be performed automatically by using a CPU before digitizing an analog input signal or at any desired time.

Abstract: A waveform observing method and apparatus incorporating signal sampling and digital technologies is disclosed. An input signal to be observed is compared with the output from a digital-to-analog converter and the comparison output is used for controlling display means such as a cathode-ray tube. A wideband input signal can be measured with much higher accuracy than the conventional apparatus.