The 420 and 430 series of oscilloscope cards from PC Instruments combine
the features and performance of portable oscilloscopes with the
convenience of the personal computer. The oscilloscope cards occupy one
PC/AT expansion slot and provide:

* 200 MHz Bandwidth,
* 500 ps/div Minimum Timebase Setting, and
* 200 Gigasample/second Equivalent Sampling Rate.

The single channel 420 series and the dual channel 430 series also provide
seven voltage ranges, AC/DC coupling, DC offset and a probe compensation
signal. Also included are 27 timebase settings from 500 ps/div to 200
ms/div, and an automatic trigger level algorithm to quickly establish a
valid trigger level.

BenchCom software is included with every oscilloscope card and provides
test engineers and systems integrators the tools necessary to integrate
the series 420 and 430 scopes into their test environment. BenchCom
provides the ability to view and print the waveform, translate the
waveform data file to an ASCII list or spreadsheet format, and control the
oscilloscope card from DOS (Basic, C, C++, Pascal) and Windows
applications via a DLL. The command set utilized by BenchCom is based on
the SCPI standard. Also available is the optional BenchTop software.
BenchTop provides a "point-and-click" graphics user interface with the
ability to store and recall waveforms, store and recall test set-ups, and
easily change settings without needing to learn the command syntax.

Reliability has been built-in to every PC Instruments scope. External
ground planes shield the scope from noise and provide a safe path for
static dissipation. The high performance of the scope is accomplished
without incorporating any adjustments or relays, therefore eliminating two
major sources of reliability problems. And, if a scope board should
develop a problem, the company will ship a free loaner in one day.

Test, production, and manufacturing engineers who are responsible for
collecting data on components, sub-systems, and complete products will
find that PC Instruments scopes out-perform data acquisition cards and
have the features engineers need to make their measurements. And, when
compared to a portable digital oscilloscope connected to a PC, the PC
Instruments scope board costs less, takes up less bench space, and does
not require an interface board (e.g. IEEE-488), interface cable, or
interface software.

Prices range from $1495 for the single channel PCI-421 with 100 MHz
bandwidth to $2695 for the dual channel PCI-434 with 200 MHz bandwidth.
BenchTop software costs $495. Availability is 6 weeks after receipt of
order. For further information contact:

PC Instruments Incorporated
9261 Ravenna Road, Building B11
Twinsburg, OH 44087-249
216-963-0800
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Technical Background Information

The circuit topology utilized on the 420 and 430 series of oscilloscopes
from PC Instruments combine traditional real-time digital oscilloscope
circuits with sequential sampling oscilloscope circuits. The real-time
circuits provide transient capture capability, while the sequential
sampling oscilloscope supply the ability to measure wide-bandwidth
repetitive waveforms. In order to obtain wide bandwidth performance within
the constraints of the PC/AT environment (limited space and limited
power), PC Instruments utilized a new circuit topology for the sequential
sampling section.

This new circuit topology started with a circuit utilized by the ATE
industry called a sampling voltage tracker. The sampling voltage tracker
utilizes a digital comparator to determine (at a specific instant of time
after the trigger) whether or not the input signal is higher or lower than
a control level. This circuit topology is somewhat related to a
sigma-delta ADC. In order to make this circuit usable in an oscilloscope,
PC Instruments had to add seven additional capabilities. These additional
capabilities were:

* Input overload protection,
* AC/DC input coupling,
* Gain controllable vertical ranges,
* A DC offset adjustment that is independent of the vertical
  range,
* Two search algorithms that quickly find the level of the input
  signal at the sampling instant,
* A timebase with 200 Gigasample/second equivalent sampling rate
  (i.e. 5 picosecond time resolution), and
* A custom DSP filter that rejects noise asynchronous to the
  trigger.

The circuit topology used for the equivalent sampling section of the
oscilloscope inherently "sweep averages" the input waveform. Sweep
averaging rejects any signal that is not synchronized to the trigger and
therefore is beneficial to those engineers that are collecting data in a
stimulus-response test such as DAC and amplifier pulse response, backplane
characterization, clock distribution, and characterizing ECL and TTL
digital circuits. Sweep averaging can be a disadvantage in a
troubleshooting application since it can hide glitches and asynchronous
noise. PC Instruments is presently developing glitch capture circuits for
inclusion on our next series of oscilloscopes.

The oscilloscope operates in a real time mode when the sweep speed is
between 2 us/div and 200 ms/div, and it operates in the sequential
equivalent sampling mode when the sweep speed is from 1 us/div to 500
ps/div. In the real time mode both channels are simultaneously sampled and
in the sequential equivalent sampling mode the oscilloscope utilizes an
alternate sweep operation.

The acquisition technique utilized for wide-bandwidth signals has several
inherent advantages when used to analyze the settling characteristics of a
pulse. The wide bandwidth of the oscilloscope (200 MHz) is complemented
with a very flat amplitude frequency response (+/-0.5dB, 10kHz to 50MHz
relative to 1 MHz) to provide excellent pulse response. Also, a DC offset
control is provided that is independent of the vertical range. Therefore,
engineers wanting to investigate the settling characteristics of a pulse
that goes from 0 volts to 1 volt, can add a 1 volt offset to the measuring
range of the oscilloscope and still use the 10 mV/div vertical range
without fear of overload recovery problems. This capability is hard to
find on any other oscilloscope product.

The waveform processing speed of the oscilloscope card is enhanced by a
custom DSP filter, a PLD, and a high-speed PROM-based state machine. Also,
the oscilloscope card can operate independently of the PC. Therefore, the
PC could start a waveform acquisition on the oscilloscope board and then
do another task while the oscilloscope board continues to collect data.
This is especially useful when combined with the oscilloscope's capability
to capture transient waveforms.

Performance does not suffer when the second channel is used. The second
channel has it's own memory and the sampling rate is not affected when the
second channel is utilized.

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