FS7755

Rev. 1.1

10/22

12.

Terminology

1

Measurement Error

The error associated with the energy measurement made by the FS7755 is defined by the following

equation:

Percentage Error =

100%

Energy

True

Energy

True

-

FS6611

by the

sured

Energy Mea

×

2

Power Supply Rejection

This quantifies the FS7755 measurement error as a percentage of the reading when the power supplies

are varied.

then introduced onto the supplies and a second reading obtained under the same input signal levels. Any

error introduced is expressed as a percentage of the reading (see Measurement Error definition).

For the dc PSR measurement, a reading at nominal supplies (5V) is taken. The supplies are then varied

±5% and a second reading is obtained with the same input signal levels. Any error introduced is again

expressed as a percentage of the reading.

3

ADC Offset Error

This refers to the dc offset associated with the analog inputs to the ADCs. It means that with the analog

inputs connected to AGND, the ADCs still see a small dc signal (offset). The offset decreases with

increasing gain in Channel V1. This specification is measured at a gain of 1. At a gain of 16, the dc offset is

typically less than 1mV.

4

Gain Error

The gain error of the FS7755 is defined as the difference between the measured output frequency (minus

the offset) and the ideal output frequency. It is measured with a gain of 1 in Channel V1. The difference is

expressed as a percentage of the ideal frequency. The ideal frequency is obtained from the FS7755

transfer function (see Transfer Function section).

5

Gain Error Match

The gain error match is defined as the gain error (minus the offset) obtained when switching between a

gain of 1 and a gain of 8, 16, or 32. It is expressed as a percentage of the output frequency obtained under

a gain of 1. This gives the gain error observed when the gain selection is changed from 1 to 8, 16, or 32.