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8-3 LOW LEVEL AND GAIN This discussion provides methods and techniques for making gain and
low-signal-level measurements. It is divided into 37xxxE system con
-
siderations and test device considerations.
37xxxE System Considerations
The 37xxxE system is limited in its ability to test low-signal levels by
its dynamic range and signal-to-noise-power ratio. First we will dis
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cuss receiver dynamic range, which is the difference between the maxi
-
mum and minimum acceptable signal levels (Receiver Dynamic Range
= Pmax – Pmin).
Receiver Dynamic Range
The dynamic range of the 37xxxE is limited by the 0.1 dB compression
level of the samplers at high signal levels. It is further limited at low
signal levels by leakage signals and noise.
Figure 8-7 shows the detected output signal as a function of the power
level at the sampler. The 0.1 dB compression level is on the order of
–10 dBm. The 37xxxE is designed such that all other conversions com-
press at a much greater level, which leaves the samplers as the main
source of nonlinearity.
The small signal response is limited by errors due to noise and leakage
signals. The leakage signals are both from within the 37xxxE and at
the device-under-test (DUT) connectors.
LOW LEVEL AND GAIN MEASUREMENTS
8-12 37xxxE OM
- 1 0
D E T E C T E D
P O W E R O U T P U T
( d B m )
P O W E R L E V E L A T I N P U T T O S A M P L E R
( d B m )
0 . 1 d B C O M P R E S S I O N
- 1 0
C O M P R E S S I O N L E V E L
Figure 8-7. Compression at 0.1 dB