Broadband Modem

Mixed-Signal Front End

AD9867

Rev. SpA

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FEATURES

FUNCTIONAL BLOCK DIAGRAM

10

RX2–

4

5

AD9867

10

0 TO –7.5dB

REGISTER

CONTROL

ADC

80MSPS

TX_DISABLE

IOUT_P+

IOUT_P–

RX2+

TxDAC

MULTIPLIER

CLK

SYN/DIST

TX PWDN

DELAY

DCTCXO

2-POLE

LPF

1-POLE

LPF

0dB TO 6dB

Δ = 1dB

SPORT

1

RXSELECT

1

ATTEN/RXQUIET

AGC[4:0]

RXCLK

RXEN/RXSYNC

ADIO[9:5]/

Tx[4:0]

ADIO[4:0]/

Rx[4:0]

TXCLK/TXQUIET

TXEN/TXSYNC

PWR_DWN

OSCIN

XTAL

– 6dB TO +18dB

Δ = 6dB

–6dB TO +24dB

Δ = 6dB

THIRD-ORDER LPF

RX1–

RX1+

2×/4×

CLKOUT1

CLKOUT2

Low cost, 3.3 V CMOS MxFE® for broadband modems

10-bit digital-to-analog converter (DAC)

2×/4× interpolation filter

250 MSPS DAC update rate

10-bit, 75 MSPS ADC

Low noise RxPGA

Dual channel muxed input

6 dB input overload attenuator

−12 dB to +48 dB (without attenuator)

Third-order programmable low-pass filter

Flexible digital datapath interface

Half-duplex and full-duplex operation

Programmable delay Tx driver disable signal

Figure 1.

Various power-down/reduction modes

Internal clock multiplier (PLL)

2 auxiliary programmable clock outputs

64-lead LFCSP

APPLICATIONS

Power-line networking

GENERAL DESCRIPTION

The AD9867 is a mixed-signal front-end (MxFE) IC for

transceiver applications requiring Tx and Rx path functionality

with data rates up to 75 MSPS. Its flexible digital interface,

power-saving modes, and high Tx-to-Rx isolation make the

part well suited for half-duplex and full-duplex applications.

The digital interface is extremely flexible allowing simple

interfaces to digital back ends. Power-saving modes can reduce

power consumption of individual functional blocks or can

power down unused blocks in half-duplex applications. A serial

port interface (SPI®) allows software programming of the

various functional blocks. An on-chip PLL clock multiplier and

synthesizer provide all the required internal clocks, as well as

two external clocks from a single crystal or clock source.

The receive path consists of a programmable amplifier

(RxPGA), a tunable low-pass filter (LPF), and a 10-bit analog-

to-digital converter (ADC). The low noise RxPGA has a

programmable gain range of −12 dB to +48 dB in 1 dB steps.

Its input referred noise is less than 3.6 nV/√Hz for gain settings

beyond 36 dB. An optional attenuator provides an additional

6 dB (or more) of attenuation (when combined with external

series resistors). The receive path LPF cutoff frequency can

either be set over a 22 MHz to 38 MHz range or simply

bypassed. The 10-bit ADC achieves excellent dynamic

performance over a 5 MSPS to 75 MSPS span. Both the RxPGA

and the ADC offer scalable power consumption allowing

power/performance optimization.

The Tx signal path consists of a bypassable 2×/4× low-pass

interpolation filter and a 10-bit, 250 MSPS TxDAC. The

transmit path signal bandwidth can be as high as 33.6 MHz at

an input data rate of 75 MSPS. The TxDAC provides differential

current outputs that can be steered directly to a differential or

single-ended external load. Tx power can be digitally controlled

over a 7.5 dB range in 0.5 dB steps.

The AD9867 provides a highly integrated solution for

broadband modems. It is available in a space-saving, 64-lead

LFCSP and is specified over the commercial (−40°C to +85°C)

temperature range.

For more information on the AD9867, contact Analog Devices,

Inc. at email MxFE_Support@analog.com.