TSA1005 datasheet(17/22 Pages) STMICROELECTRONICS

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TSA1005

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Figure 7: Medical imaging application

The transducer is a piezoelectric ceramic such as

zirconium titanate. The whole array can reach up

to 512 channels.

The TX beam former, amplified by the HV TX

amps, delivers up to 100V amplitude excitation

pulses with phase and amplitude shifts.

The mux and T/R switch is a two way input signal

transmitter/ output receiver.

To compensate for skin and tissues attenuation

effects, The Time Gain Compensation (TGC) am-

plifier is an exponential amplifier that enables the

amplification of low voltage signals to the ADC in-

put range. Differential output structure with low

noise and very high linearity are mandatory fac-

tors.

These applications need high speed, low power

and high performance ADCs. 10-12 bit resolution

is necessary to lower the quantification noise. As

multiple channels are used, a dual converter is a

must for room saving issues.

The input signal is in the range of 2 to 20MHz

(mainly 2 to 7MHz) and the application uses most-

ly a 4 over-sampling ratio for Spurious Free Dy-

namic Range (SFDR) optimization.

The next RX beam former and processing blocks

enable the analysis of the outputs channels ver-

sus the input beam.

EVAL1005/BA evaluation board

The EVAL1005/BA is a 4-layer board with high

decoupling and grounding level. The schematic of

the evaluation board is reported figure 11 and its

top overlay view figure 10.The characterization of

the board has been made with a fully ADC

devoted test bench as shown on Figure 8. The

analog input signal must be filtered to be very

pure.

The dataready signal is the acquisition clock of the

logic analyzer.

The ADC digital outputs are latched by the octal

buffers 74LCX573.

All characterization measurements have been

made with:

- SFSR=1dB for static parameters.

- SFSR=-1dB for dynamic parameters.

Figure 8: Analog to Digital Converter characterization bench

Mux

and

Proces

TGC amplifier

HV TX amps

Sine Wave

Generator

HP8644

ADC

evaluation

Pulse

Logic

Sine Wave

Generator

HP8644

HP8133

Vin

Clk

Data

Clk

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