Analog front end (AFE)

ST7590

14/24

Doc ID 18349 Rev 1

4

Analog front end (AFE)

4.1

Reception path

Figure 5 shows the block diagram of the ST7590 input receiving path. The reception AFE

main blocks are a wide input range analog PGA (programmable gain amplifier) and the ADC

(analog to digital converter).

Figure 5.

Reception path block diagram

The PGA is controlled by a loop algorithm that detects the amplifier output signal amplitude

and adapts the gain of the amplifier in order to have the optimum input voltage range for the

ADC. The PGA gain ranges from -18 dB up to 30 dB (typical), with steps of 6 dB (typical), as

described in Table 5.

Table 5.

PGA gain table

PGA code

PGA gain (typical)

RX_IN max range

[dB]

[V p-p]

0-18

16

1-12

8

2-6

4

30

2

46

1

5

12

0.500

6

18

0.250

7

24

0.125

8

30

0.0625