EVAL1201/AA View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'EVAL1201/AA' PDF : 20 Pages View PDF
TSA1201
to VINB and INCM. The latest imposes its voltage.
VREFP being internally set to 1V, the dynamic is
then 1Vpp.
Figure 3 : DC-coupled 2Vpp analog input
Analog
DC
Analog+DC
VIN VREFP
TSA1201
VINB VREFM
INCM
330pF
10nF 470nF
Figure 4 : DC-coupled 1Vpp analog input
Analog
DC
Analog+DC
VIN
TSA1201
VINB VREFM
INCM
330pF
10nF 470nF
IF-sampling
Software radio has become a common mode for
receiving data through RF receivers. Its main
advantage being to digitally implement what was
originally done with analog functions such as
discriminators, demodulation and filtering.
Originally, bipolar process was mainly used
because they provided high transistor transit
frequency, while pure CMOS technology showed
a lower one. With new CMOS process and circuit
topology, higher frequencies are now achieved.
The TSA1201 has been specifically designed to
meet the requirement of sampling at Intermediate
Frequency. For this purpose, the Track-and-Hold
of the first pipeline stage has been built to ensure
the global linearity of the overall ADC to perform
the right characteristics.
Our proprietary Track-and-Hold has a patented
switch control system to enable the performances
not to be degraded as input signal frequency
increases.
As a result, an analog bandwidth of 1GHz is
achieved.
REFERENCE CONNECTION
Internal reference
In the standard configuration, the ADC is biased
with the internal reference voltage. VREFM pin is
connected to Analog Ground while VREFP is
internally set to a voltage of 1.0V. It is
recommended to decouple the VREFP in order to
minimize low and high frequency noise. Refer to
Figure 5 for the schematics.
Figure 5 : Internal reference setting
1.0V
330pF
VIN VREFP
TSA1201
VINB
VREFM
10nF 470nF
External reference
It is possible to use an external reference voltage
instead of the internal one for specific applications
requiring even better linearity or enhanced
temperature behaviour. In this case, the amplitude
of the external voltage must be at least equal to
the internal one (1.0V). Using the
STMicroelectronics Vref TS821 leads to optimum
performances when configured as shown on
Figure 6.
Figure 6 : External reference setting
1kΩ
VCCA VREFP
VIN
TSA1201
VINB
VREFM
330pF
TS821
external
reference
10nF 470nF
This can be very helpful for example for
multichannel application to keep a good matching
over the sampling frequency range.
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