Agilent Technologies 34401A manual Loading Errors ac volts, For low frequencies

Chapter 7 Measurement Tutorial

Loading Errors (ac volts)

Loading Errors (ac volts)

In the ac voltage function, the input of the Agilent 34401A appears as a 1 MΩ resistance in parallel with 100 pF of capacitance. The cabling that you use to connect signals to the multimeter will also add additional capacitance and loading. The table below shows the multimeter’s approximate input resistance 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:

() = − 100 x Rs Error %

+1 MΩR

s

Additional error for high frequencies:

Error (%) =	100	￿	1	− 1	￿
		x ￿			￿
		￿	√ 1 + ( 2 π x F x Rs x Cin )2		￿
		￿			￿
		￿			￿

Rs = source resistance

F = input frequency

Cin = input capacitance (100 pF) plus cable capacitance

7

209