INTRODUCTION The LeCroy 9420 is a wide bandwidth digital oscilloscope suited to a variety of engineering design and test applications. It is used to capture, analyze, display and archive electrical waveforms in fields such as analog and digital engineering, automated test and measurement, telecommunication and electronics research. 9420 ARCHITECTURE The 9420 features two 1.00 mega sample/second 8-bit Flash ADC systems, two 5OK non-volatile memories for waveform acquisition and storage, and an additional four 50K memories for waveform processing and temporary storage. High-speed internal data transfer and processing are performed using a multi-processor system. The central processor is a powerful Motorola 68020 microprocessor which performs computations and controls the oscilloscope’s operation. All front-panel knobs and buttons are constantly monitored by the internal processor, and front-panel setups are rapidly reconfigured via the unit’s internal 16-bit bus. Data are quickly processed according to the selected frontpanel setups, and are transferred to the display memory for direct waveform display or stored in the 9420’s reference memories. The 68020 controls the unit’s GFIB (IEEE-488) remote control port, as well as the RS-232-C port which is used to directly interface the 9420 to a digital plotter, printer, remote terminal or other slow-speed device. ADCs AND MEMORIES Each of the 9420’s two identical input channels is equipped with a 00 megasample/second, 8—bit ADC and a 50 kiloword acquisition memory (see Figure 4). This dual ADC architecture ensures absolute amplitude and phase correlation, maximum ADC performance for both single- and dual-channel acquisition modes, large record lengths and excellent time resolution. The 9420’s two 5OK acquisition memories simplify transient capture by providing very long waveform records that capture waveforms even when trigger timing or signal speed is uncertain. In addition, a special expansion facility magnifies waveforms by up to 1000 times the selected time-base speed. The 9420 oscilloscope is capable of acquiring and storing repetitive signals at a Random Interleaved Sampling (RIS) rate of 10 giga-samples/second. RIS is a high-precision, digitizing technique that enables measurement of repetitive signals to a bandwidth of 350 MHz with an effective sampling interval of 100 psec and measurement resolution of 5 psec. The 9420 assures precision measurements over its entire range of operation. TRIGGER The 9420’s digitally-controlled trigger system offers an extensive range of trigger capabilities. Front-panel and menu controls let the user choose the appropriate trigger function for the signal. In the standard trigger mode the 9420’s front-panel controls are used to select and set parameters such as pre- and post-trigger recording, sequence and roll modes, in addition to the Auto, Normal and Single (Hold) modes. The trigger source can be line, external or either of the two inputs. The coupling is selected from HF, AC, LF REJect, HF REJect and DC and the slope from positive and negative. The SMART trigger facility provides a complete range of sophisticated and versatile trigger features. The following trigger classes and operational modes are available: AUTOMATIC CALIBRATION The 9420 has an automatic calibration facility that ensures overall vertical accuracy of db 2% of full scale and a time-base interpolator accuracy of db 20 psec RMS for the unit’s crystal-controlled time base. The time base is calibrated each time the 94205s time-base control is adjusted to a new Time/div setting; vertical gain and offset calibration take place each time the front-panel fixed gain control for either Chan 1 or Chan 2 is adjusted to a new Volts/div setting. Both channels are also calibrated each time the Bandwidth Limit button is pressed. In addition, the 9420 performs periodic calibration to ensure the long term stability at a particular setting. DISPLAY The 9420’s large 12.5 X 17.5 cm (5 X 7 inches) screen displays waveforms with high resolution and serves as an interactive, user-friendly interface via a set of pushbuttons located immediately to the left and right of the CRT. The oscilloscope displays up to four waveforms, while simultaneously reporting the parameters controlling signal acquisition. In addition, the screen presents internal status and measurement results, as well as operational, measurement, and waveform analysis menus. A hard copy of the 9420’s screen is available via the unit’s front-panel screen dump button. Plotting is done in parallel with normal oscilloscope operation.