Datasheet

UPSTREAM

DOWNSTREAM

4.5kHz 30kHz

135kHz

160kHz

1.1MHz

FREQUENCY

POTS

POWER SPECTRUM

LMH6622

SNOS986D –DECEMBER 2001–REVISED MARCH 2013

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DSL RECEIVE CHANNEL APPLICATIONS

Figure 36. ADSL Signal Description

The LMH6622 is a dual, wideband operational amplifier designed for use as a DSL line receiver. In the receive

band of a Customer Premises Equipment (CPE) ADSL modem it is possible that as many as 255 Discrete Multi-

Tone (DMT) QAM signals will be present, each with its own carrier frequency, modulation, and signal level. The

ADSL standard requires a line referred noise power density of -140dBm/Hz within the CPE receive band of

100KHz to 1.1MHz. The CPE driver output signal will leak into the receive path because of full duplex operation

and the imperfections of the hybrid coupler circuit. The DSL analog front end must incorporate a receiver pre-

amp which is both low noise and highly linear for ADSL-standard operation. The LMH6622 is designed for the

twin performance parameters of low noise and high linearity.

Applications ranging from +5V to +12V or ±2.5V to ±6V are fully supported by the LMH6622. In Figure 37, the

LMH6622 is used as an inverting summing amplifier to provide both received pre-amp channel gain and driver

output signal cancellation, i.e., the function of a hybrid coupler.

Product Folder Links: LMH6622