RIGOL DM3068 - Manual (Page 146)

RIGOL Chapter 5 Measurement Tutorial
User’s Guide for DM3068 5-6
Loading Errors (ACV)
In the AC Voltage function, the input impedance of DM3068 appears as a 1 MΩ
resistance in parallel with 100 pF of capacitance. The test lead of the multimeter
will also add additional capacitance and load.
The table below gives the multimeter’s approximate input resistance at various
frequencies.
Table 5-2 Resistances at various frequencies
Input Frequency Input Resistance
100 Hz 1 MΩ
1 kHz 850 kΩ
10 kHz 160 kΩ
100 kHz 16 kΩ
For low frequencies:
Loading Error (%)
% 100
1M Rs
R -
s
×
Ω +
=
Additional error for high frequencies:
Loading Error (%)
% 100 1
) 2 ( 1
1
Ч








−
Ч Ч Ч +
=
in s
C R F
π
s
R
: internal resistance of the signal generator
F
: input frequency
in
C
: input capacitance (100 pF) plus test lead capacitance