ATU-R RX Filters

The integrated filter have the following characteristics:

Table 6. Integrated HC Filter Characteristics

Description

Value/Unit

Input referred noise

100nVHz

-1/2

Max. input level

1Vpd

Max. output level

1Vpd

Type

3rd order butterworth

Frequency band

1.104MHz (0%setting, see below)

Frequency tuning

-43.75% -> +0%

Max. in-band ripple

1dB

Matlab Model

Default cut off frequency @ -3dB

Actual cut off @ -3dB

HC Freq. selection register

[B, A] = butter (3, w0, ’s’)

F0 = 1560KHz

w0 = 2 * pi * F0/((20 + n)/16)

n = -4,..,3

see (AFE settings ,Table 22)

Table 7. Phase Characteristic

Description

Value/Unit

Total RX filter group delay

< 50

µs @ 138kHz < f < 1.104MHz

TotalRX filter group delay distortion

< 15

µs @ 138kHz < f < 1.104MHz

Note: The total ATU_R RX path (including ADC) group delay distortion is 16

µs (i.e. = 15µs+ 1µs of ADC)

ATU-C RX filter

This filter is the same as the one used for ATU-R TX.

Linearity of RX

Linearity of the RX analog path is defined by the IM3 product of two sinusoidal signals with frequencies

f1 and f2 and each with 0.5Vpd amplitude (total

≤ 1Vpd) at the output of the RX - AGC amplifier (i.e: be-

fore the ADC) for the case of minimal AGC setting.

The following tables 8 and 9 list the RX path intermodulation distortion (as S/IM3 ratio) in downstream

and upstream bandwidth.

AMPLITUTDE

0dB

+/-1dB

5dB

36dB

50dB

30

1104 2208

7728

16560

kHz

D98TL360

Figure 7. HC Filter Mask for ATU-R RX and ATU-C TX

Table 8. Linearity of ATU-R RX

f1 (0.5Vpd)

f2 (0.5Vpd)

300kHz

200kHz

500kHz

400kHz

700kHz

600kHz

S/IM3 (AGC = 0dB)

59.5dB @ 100kHz

53.5dB @ 400kHz

43.5dB @ 700kHz

42.5dB @ 800kHz

59.5dB @ 300kHz

48.0dB @ 600kHz

48.0dB @ 500kHz

42.5dB @ 800kHz

STLC60134S

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