Frequency Response Below 300 kHz Performance Test

The Frequency Response 300 kHz to 3 GHz Performance Test must be performed before running this test.

Frequency Response (or flatness) is defined as the amplitude deviation from the reference value at 50 MHz. The complete E444XA Frequency Response is measured with three different tests:

The Frequency Response Below 300 kHz test is used to verify flatness from 10 Hz to 300 kHz. The 300 kHz normalized error from the Frequency Response 300 kHz to 3 GHz test is used as the reference point for the Frequency Response Below 300 kHz test. 

The Frequency Response Above 3 GHz test verifies flatness from 3.0 GHz up to 50 GHz, depending on your instrument frequency range.

This test measures the E444XA flatness over the frequency range from 10 Hz to 300 kHz, relative to the amplitude at 300 kHz. This relative flatness is converted to an absolute flatness by adding the 300 kHz flatness error from the Frequency Response (300 kHz to 3 GHz) test.

A function generator, and a multimeter1 are used in the test. The function generator and DVM provide an accurate, flat CW level of 0.0707 V (RMS) (-10 dBm into 50 ohms) to the E444XA. This is the same input level that is used in the 300 kHz to 3 GHz test.

The E444XA measures the amplitude of the signal in dBm. Flatness (frequency response) is defined as the difference between the multimeter reading and the E444XA reading in dB.

The E444XA has three flatness correction points below 300 kHz. The correction points are 9 kHz, 50 kHz, and 200 kHz. The firmware applies the 9 kHz Flatness Correction as an offset to all points below 9 kHz.

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Required Test Equipment

Test Equipment

Model Number

Function Generator

33622A 

Digital Multimeter1

3458A 

BNC Cable (3 required)

8120-2582 

Type-N (m) to BNC (f) adapter

1250-1476

BNC (f) to dual banana adapter

1251-2277

BNC Tee

1250-0781

Type-N (f) to 3.5 mm (f) adapter 
(for E4440A/43A/45A Option BAB)

1250-1745

Type-N (f) to 2.4mm (f) adapter
(for E4446A/47A/48A)

11903B

  1. The digital multimeter should be in a thermally stable environment with its power turned on for at least 2 hours before performing any autocal. For maximum accuracy, you should perform ACAL ALL once every 24 hours or when the multimeter's temperature changes by ± 1 °C from when it was last externally calibrated or from the last autocal.

Connection Setup