LMH6622 Datasheet, PDF (17/33 Pages) National Semiconductor (TI) – Dual Wideband, Low Noise, 160MHz, Operational Amplifiers

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9 Application and Implementation
9.1 DSL Receive Channel Applications
LMH6622
SNOS986E – DECEMBER 2001 – REVISED JULY 2014
POTS
UPSTREAM
DOWNSTREAM
4.5kHz
30kHz
135kHz 160kHz
1.1MHz
Figure 35. ADSL Signal Description
FREQUENCY
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 -140 dBm/Hz within the CPE receive band of 100
KHz to 1.1 MHz. 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.
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