Product specifications

Internal pulse generators start generating the pulses approximately 60 to

100 ns after the pulse trigger inputs at the PULSE SYNC IN – (denoted as

pulse trigger delay). The jitter of this delay is the minimum time resolution

of the system. The exact pulse trigger delay can be measured with an

oscilloscope between PULSE SYNC IN and one of the PULSE OUT (P1

through P4). If the internal clock is used to trigger the pulse generators,

this pulse trigger delay is very small and therefore it can be neglected. One

of the P1 through P4 internal pulse generators drives the internal pulse

modulators to generate pulsed-RF signals. The actual pulsed-RF signals

have a delay of approximately 30 ns from the P1 through P4 modulation

pulse at the test port with a 48 inch RF test port cable – (denoted as pulse

modulation delay). The pulse modulation delay with RF carrier frequencies

of 3.2 GHz and below is about 40 ns or larger (nearly 100 ns delay at the

low-end frequency of the analyzer). The combiner path on port 1 adds an

additional 5 ns delay compared to the thru path. The pulse modulators

switch the RF sources on and off with approximately

4 ns rise time and 10 ns fall time.

P0 pulse generator is also triggered by PULSE SYNC IN (or internal

trigger) and generates a data acquisition pulse with the same amount of

pulse trigger delay as other internal pulse generators (or zero if triggered

internally). Although the data acquisition process starts immediately with

the P0 pulse, there is approximately 250 ns data-processing delay, the

time it takes for sampled data with pulse on to become available in the

buffer. The user-specified measurement delay (the delay for P0) must take

into account these data-acquisition and pulse-modulation delays to align

the pulsed stimulus and data-acquisition window. Approximately 300 ns

for the measurement delay accounts for pulse-modulation delay and data-

acquisition delay, as well as pulse-settling time. Additional delay may be

necessary depending on the frequency, the PNA-X’s internal path switches,

and external cables and devices.

Setting up pulsed-RF measurements

The basis of pulsed-RF point-in-pulse measurements with wideband detection

method is to synchronize pulsed stimulus and data acquisition so that all

receivers measure responses only within the RF pulses. The following three

steps must be completed for successful measurements.

Step 1 Setup pulse generators and modulators

Specify pulse width, delay and period for internal pulse generators with Pulse

Generator Setup dialog (Figure 10a). Note that Pulse0 width is determined

by the IF bandwidth chosen (in step 3) thus it is not editable on the pulse

generator dialog. When internal pulse modulators are used, specify the drive

source (typically one of internal pulse generators). It is also required to disable

automatic level control (ALC) on the source port with pulse modulation

enabled. Change the leveling mode from “Internal” to “Open loop” on Power

and attenuator dialog. Otherwise the ALC will try to level the source with the

detected power level with pulse on and off, causing a source unleveled error.