Analog front end (AFE)

ST7570

14/26

Doc ID 17526 Rev 2

Figure 6.

Transmission path block diagram

The amplitude of the transmitted signal can be set on a 32-step logarithmic scale through

the TX_GAIN parameter, introducing an attenuation ranging from 0 dB (typ.), corresponding

to the TX_OUT full range, down to -31 dB (typ.).

The attenuation set by the TX_GAIN parameter can be calculated using the formula of

Equation 1:

Equation 1 Output attenuation A [dB] vs. TX GAIN

5.3

Power amplifier

The integrated power amplifier is characterized by very high linearity, required to be

compliant with the different international regulations (CENELEC, FCC etc.) limiting the

spurious conducted emissions on the mains, and a current capability of 1 A rms that allows

the amplifier driving even very low impedance points of the network.

All the pins of the power amplifier are accessible, making it possible to build an active filter

network to increase the linearity of the output signal.

AdB

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TX_GAIN

31

–

() TX_GAIN

TOL

+

=