TSA1201 datasheet(14/20 Pages) STMICROELECTRONICS

14 / 20 page

TSA1201

14/20

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

Figure 4 : DC-coupled 1Vpp analog input

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

voltage

1.0V.

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

External reference

It is possible to use an external reference voltage

instead of the internal one for specific applications

requiring

even

better

linearity

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

This

can

very

helpful

for

example

for

multichannel application to keep a good matching

over the sampling frequency range.

TSA1201

VIN

VINB

INCM

330pF

470nF

10nF

Analog

Analog+DC

VREFP

VREFM

TSA1201

VIN

VINB

INCM

330pF

470nF

10nF

Analog

Analog+DC

VREFM

TSA1201

VIN

VINB

VREFM

1.0V

VREFP

330pF

470nF

10nF

Ω

TSA1201

VIN

VINB

VREFM

VREFP

external

reference

TS821

VCCA

330pF

470nF

10nF

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