ST70134 - ST70135A

3/8

ASCOT ICs

ASCOT

consists

of

an

Analog

Front

End

(ST70134) and a Discrete Multitone Modem

(ST70135A)

integrated

circuits

which

are

produced by STMicroelectronics.

Here below we will briefly go through the main

topics of both the ICs (see Figure 2 and Figure 3).

Analog Front End (ST70134)

HCMOS5A (0.5

µm) mixed digital and analog

technology has been chosen to produce this

component that embodies the analog functions of

the ASCOT.

Automatic gain control amplifiers, placed at the

analog interface of transmit and receive paths,

allow to keep acceptable level of the signal ADC’s

and DAC’s resolution, that is 12-bit wide with

8.8MHz sampling rate.

A

built-in

driver

allows

for

external

clock

generation using a VCXO.

ST70134 Analog Front End’s main features:

– Rx low noise amplifier (0-31dB in 1dB steps

– Tx pre-driver amplifier (-15dB -0)

– Two input ports allow selection of RX signals,

e.g. with or without external attenuation

– Programmable low pass and band pass filters

– 12-bit DAC and ADC, sampling at 8.832MHz

– Xtal: 35.328MHz,

±50ppm, the accuracy of the

frequency is determined by the External XTAL

– Direct connection to ST70135A DMT modem

– Error correction on ADC output

– Analog and digital loop back modes

– Single 3.3V supply, or 3.3V analog and 3.0V

digital supplies

– Power dissipation 0.4W

– Power-down mode 0.1W

– TQFP64 (10 x 10mm body, 0.5mm pitch)

Figure 2 : Analog Front End block diagram

MUX

4

LPF

138KHz

G = -15...0dB

STEP 1dB

VCODAC

XTAL DRIVER

TRANSMIT-SIDE

MUX

RECEIVE-SIDE

4

DAC

DAC

12 Bits / 8.8MHz

12 Bits / 8.8MHz

LPF

1.1MHz

LNA

G = 0...31dB

STEP 1dB