ST-2 M
INI
-N
OISE
D
IODES
10 KH
Z TO
3 GH
Z
D
ESCRIPTION
Micronetics' ST-2 Diode with
its small, surface mount SOT-
23 package are ideally suited
for medium and high volume
production circuits. Their
Gaussian wideband highly
stable noise characteristics
make them ideal for several
applications from built-in
Microwave receiver calibra-
tion, to A/D dithering.
P
INOUT
M
INI
-N
OISE
D
IODE
S
PECIFICATIONS
MODEL
NUMBER
FREQUENCY
RANGE
OUTPUT
(1)
ENR dB
(min)
FLATNESS (2)
dB
(max)
TYP BIAS
(2)
CURRENT (max)
TYP DC+
BIAS
Pin 1 - Ground
Pin 2 - Bias/Noise Output
Pin 3 - N/C
See style code Z on our web-
site for additional outline
details:
http://www.micronetics.com
ST-2
10 KHz - 1 MHz
1 MHz – 100 MHz
100 MHz – 3 GHz
33
30
28
2.0
2.0
2.0
2-4 mA
2-4 mA
2-4 mA
5.2v
5.2v
5.2v
(1) ENR is measured in a 50 ohm system.
(2) Spectral response varies with bias current. Differing levels of ENR and in-band flatness
can be realized by adjusting bias current.
Application Notes:
Microwave Receiver Calibration: There are two built-in tests commonly performed with
noise. One is a straightforward noise figure or noise temperature test. The other is a spec-
tral calibration, which uses the broadband flat frequency output of the noise to test frequen-
cy response. This test typically requires a higher amplitude noise signal than the noise
temperature test and may require a gain stage to boost the signal.
A/D Converter Dithering Circuit: Sensitivity can be increased significantly when summing
low frequency noise (in the range of 10 KHz - 5 MHz depending on the A/D converter) with
the IF frequency prior to the input of the A/D Converter. The noise signal amplitude needs
to be boosted significantly from the output of the noise diode. Designers usually take two
approaches, one at 50 ohm in which standard radio frequency gain blocks are used and
the noise is combined with the signal at 50 ohms. The signal +noise is then converted to
high impedance prior to being fed into the A/D. The second uses op amps to boost the
noise signal and the noise is summed with the signal all at high impedance and fed directly
into the A/D.
Encryption: In this usage, the Gaussian output of the noise is used to generate random
numbers by sampling the voltage of the noise using an A/D converter. Frequency require-
ments are usually a function of the system parameters of the random numbers desired. As
with the dithering circuit, the noise amplitude form the diode needs to be boosted with gain.
These circuits are typically high impedance.
MICRONETICS / 26 HAMPSHIRE DRIVE / HUDSON, NH 03051 / TEL: 603-883-2900 / FAX: 603-882-8987
WEB: WWW.MICRONETICS.COM
MICRONETICS [ MICRONETICS, INC. ]
