SRS Tech Note ________________________________________________________________________________________________________________________________________________________________________
________________________________________________________________________________________________________________________________________________________________________ Stanford Research Systems February 2020
Tel: (408)744-9040 · www.thinkSRS.com
This note summarizes the output stability and noise performance of the DC205 Precision DC Voltage Source, compared with a Yokogawa model 7651 Programmable DC Source.
SRS DC205 Yokogawa Ranges compared ±1 V, ±10 V, and ±100 V ±1 V, ±10 V, ±32 V Resolution (ppm of full scale)
1 ppm 1 µV (1 V), 10 µV (10 V), 100 µV (100V)
10 ppm 10 µV (1 V), 100 µV (10 V), 1 mV (32V)
Output stability from cold power-on
Overnight stability
9.999 700
9.999 750
9.999 800
9.999 850
9.999 900
9.999 950
10.000 000
10.000 050
0 600 1200 1800 2400 3000 3600
Out
put (
V)
Elapsed time from turn-on (s)
DC205 10VYoko 10V
±1 ppm of settled value
DC205 settled after only 10 minutes from power-on
Yokogawa needs more than 30 minutes to settle from power-on
25.5
26
26.5
27
27.5
28
28.5
29
9.999 900
9.999 920
9.999 940
9.999 960
9.999 980
10.000 000
10.000 020
10.000 040
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Room
tem
pera
ture
(°C)
DC O
utpu
t (V)
Elapsed time (hr)
DC205 Yoko 7651 Temperature
________________________________________________________________________________________________________________________________________________________________________ Stanford Research Systems 2
Tel: (408)744-9040 · www.thinkSRS.com
Low frequency noise measured through 200 mF blocking capacitor into a SR554 Transformer Preamplifier and SR560 Preamplifier. Total gain ×10,000.
Low frequency noise (0.3 Hz to 10 Hz) SRS DC205 Yokogawa 7651
Out
put =
1 V
1 µV / div O
utpu
t = 1
0 V
1 µV / div O
utpu
t = 3
0 V
2 µV / div 1 s / division 1 s / division
Pk-Pk: 1.5 µV RMS: 0.24 µV
Pk-Pk: 1.6 µV RMS: 0.26 µV
Pk-Pk: 1.9 µV RMS: 0.37 µV
Pk-Pk: 4.6 µV RMS: 0.75 µV
Pk-Pk: 7.8 µV RMS: 1.2 µV
Pk-Pk: 11.6 µV RMS: 2.2 µV
________________________________________________________________________________________________________________________________________________________________________ Stanford Research Systems 3
Tel: (408)744-9040 · www.thinkSRS.com
High frequency noise measured directly with a SR560 Preamplifier, gain ×1000.
High frequency noise (10 Hz to 1 MHz) SRS DC205 Yokogawa 7651
Out
put =
1 V
500 µV / div O
utpu
t = 1
0 V
500 µV / div O
utpu
t = 3
0 V
500 µV / div 5 ms / division 5 ms / division
Noise measurements performed on DC205 (s/n 20500097) and Yokogawa 7651 (s/n 27D134535A). The DC205 30 V measurements were made on the 100 V output range, to compare with the 7651 maximum output range of 30 V. Both sources were operated with ground-referenced outputs.
Pk-Pk: 220 µV RMS: 24 µV
Pk-Pk: 2.8 mV RMS: 38 µV
Pk-Pk: 220 µV RMS: 23 µV
Pk-Pk: 2.8 mV RMS: 38 µV
Pk-Pk: 380 µV RMS: 47 µV
Pk-Pk: 2.2 mV RMS: 36 µV
________________________________________________________________________________________________________________________________________________________________________ Stanford Research Systems 4
Tel: (408)744-9040 · www.thinkSRS.com
High frequency power spectum (to 2.5 MHz) Measured with an HP Model 89410A 10 MHz Vector Signal Analyzer. Span DC to 2.5 MHz, RBW=1 kHz.
SRS Model DC205
Range = 100 V, Setting = 0 V
Yokogawa Model 7651
Range = 30 V, Setting = 0 V
Noise floor of measurement
(HP 89410A input shorted)
250 kHz / div
10 n
V/√H
z / d
iv
10 n
V/√H
z / d
iv
10 n
V/√H
z / d
iv
250 kHz / div
250 kHz / div
________________________________________________________________________________________________________________________________________________________________________ Stanford Research Systems 5
Tel: (408)744-9040 · www.thinkSRS.com
Comparison of the output resolution (least-significant steps) for the DC205 Precision DC Voltage Source and the Yokogawa model 7651 Programmable DC Source. Both instruments are set to an output range of 10 V. Note the step-to-step variation in the Yokogawa output, as well as the 10-fold resolution advantage of the DC205. Least-significant output steps
9.999 900
10.000 000
10.000 100
10.000 200
10.000 300
10.000 400
10.000 500
10.000 600
Out
put (
V)
DC205
Yokogawa
10.000 000
10.000 010
10.000 020
10.000 030
10.000 040
10.000 050
10.000 060