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Chapter 3: Testing Performance
To test bandwidth
3–13
To test bandwidth
This test checks the bandwidth of the oscilloscope. The Agilent 54845A bandwidth at 1.5 GHz
and the Agilent 54846A bandwidth at 2.25 GHz oscilloscopes are checked using aliasing since
the trigger specification of these oscilloscopes is 1 GHz. The 1.5 GHz or the 2.25 GHz signal is
viewed with a time/division setting of approximately 50
µs/div where the on-screen display is an
untriggered sinewave that appears to be at a lower frequency, however the vertical response of
the amplifiers is correct. The Agilent 54835A bandwidth at 1.0 GHz and 500 MHz of all three
models is checked normally.
Specification
Equivalent Time:
50
Ω: 2.25 GHz (Agilent 54846A), 1.5 GHz (Agilent 54845A), 1.0 GHz (Agilent 54835A)
1 M
Ω: 500 MHz (with Agilent 1161A probe)
Real Time:
50
Ω: for Agilent 54846A — 2.25 GHz (2-channel mode), 1.0 GHz (4-channel mode)
50
Ω: for Agilent 54845A — 1.5 GHz (2-channel mode), 1.0 GHz (4-channel mode)
50
Ω: for Agilent 54835A — 1.0 GHz (2-channel mode), 500 MHz (4-channel mode)
1 M
Ω: 500 MHz (with Agilent 1161A probe)
Equipment Required
Equivalent Time Test
1
Connect the equipment.
a With the N cable, connect the signal generator to the power splitter input. Connect the
power sensor to one output of the power splitter.
b With an N-to-BNC adapter, connect the other splitter output to the channel 1 input.
2
Press Default Setup to set the oscilloscope to default conditions.
3 Select Acquisition from the Setup menu. Select Equivalent Time sampling mode. Click
Close. Select Display from the Setup Menu. Unselect Connect Dots mode. Click Close.
4 Set the vertical scale for Channel 1 to 100 mV/div using the knob. Select 50Ω input
impedance.
5 Set the sweep speed to 50 ns/div using the horizontal sweep speed knob.
6 Set the signal generator for 10 MHz at +5.0 dBm.
The signal on the oscilloscope screen should be about five cycles at six divisions amplitude.
Equipment Critical Specifications Recommended Model/Part
Signal Generator 10—2250 MHz at ≈200 mVrms Agilent 8664A
Power Meter/Sensor 1—1.5 GHz ±3% accuracy Agilent EPM-441A/8482A
Power Splitter outputs differ by <0.15 dB Agilent 11667A
Cable Type N (m) 24 inch Agilent 11500B
Termination 50Ω, BNC Connectors Agilent 10100C
Adapter Type N (m) to BNC (m) Agilent 1250-0082
Probe No Substitute Agilent 1161A
Probe Tip Adapter 1160 Series to BNC Agilent 5063-2143
Bandwidth Check Limits
Do not exceed 6 divisions when making the bandwidth check.