These Philips dual-output pulse generators satisfy the
general-purpose high-speed requirements for both linear and
digital applications. The PM 5785/85B units, with a
performance of 125 MHz/1 ns (into 50 Ohms), feature
extremely fast output waveform rise and fall transition
times that can be adjusted in three steps. A feature of the
PM 5786/86B units, with their performance of 125 MHz/2 ns
(into 50 Ohms), is that both rise and fall transition times
can be adjusted independently. Versatility is provided by
the wide choice of external triggering and gating of the
generators, various output modes of operation and for the
"B" versions a pushbutton settable burst waveform facility.
The layout of the front-panel, which facilitates easy
operation, is further enhanced by LED indicators that
highlight time-setting errors.
These indicators help to avoid erroneous output waveforms
due to incorrectly interrelated settings of the pulse delay,
pulse duration and for the PM 5786 units, the rise and fall
Clean, high-speed pulses
The pulse generators feature high-speed, high- fidelity
performance; ideal for all high-speed TTL and ECL circuit
testing. The 20-80% transition times for ECL testing are
selectable on the PM 5785 units down to 0.7 ns and variable
on the PM 5786 units down to 1.4 ns.
The 5 V bipolar outputs (into 50 Ohms), together with the
high quality four range output attenuators, make these
generators suitable for all kinds of linear applications.
Clean pulses are guaranteed due to the excellent 50 Ohm
back- matching impedances that absorb over 90% of all
reflections coming from mis-matched (non 50 Ohm) loads.
Selection of the outputs provides simultaneous positive- and
negative-going waveforms often required for bipolar and
linear applications, as well as complementary positive or
negative waveforms for digital applications. The waveforms
at the output sockets A and B are synchronous and are of the
same amplitude, however the DC offset controls can be used
to individually offset each output by ±2.5 V (into 50 Ohms).
The choice of bipolar, positive or negative complementary
waveforms offers an easy method of selecting the required
output. This eliminates the need for "knob-twiddling" with
inverting amplifiers and offset controls. Further, the COMPL
(normal/complementary) switch allows the logic levels at the
output sockets A and B to be interchanged without affecting
The external input facility allows external control signals
to be used for triggering, gating, initiating an output
waveform burst and "external duration". Such control signals
can define the start (and with EXT DUR selected, the
duration) of the output waveforms by the selection of +/-
edge triggering and the adjustment of the -3 V...+3 V
trigger level control. Triggering is indicated by a flashing
All functions available through the use of the external
input can be carried out manually from the front panel.
External triggering allows the generators to operate in
synchronism with other clock input signals. All other
parameters, such as pulse duration, pulse delay, etc, are
set on the pulse generators themselves. The acceptable
external trigger signal frequency range is DC...125 MHz or,
in the double pulse mode, DC«...62.5 MHz.
The external gate mode is a generator output "ON/OFF”
control. When the external gate signal is present, the
output waveforms are available with the pre-set pulse
The "B" versions allow the generation of output waveform
bursts containing pre-settable numbers of pulses:
0.....9999. These bursts can be initiated either manually,
or by an external input signal.
The "external duration" mode allows the generators to
function as input signal conditioners. Pulse period and
duration are defined by external input signals whereas
amplitude, DC-offset, leading and trailing edge transition
times and the normal/complementary modes are defined by the
pulse generator settings.
U "Symmetrical" pulse
This mode of operation produces waveforms with a constant
0.5 duty factor and therefore facilitates the use of the
units as clock pulse generators or as a quick method of
determining the output waveform repetition rates.
LED indicators highlight timing errors
Setting-up errors occur because, for example, pulse period
can be set to less than the sum of the other selected pulse
timing parameters. Time-setting-error LEDs indicate which
timing parameter settings are excessively long with regard
to pulse period.