 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
AN84 Datasheet(PDF) 1 Page - Silicon Laboratories |
|
|
|||||||||||||||||||||||||||||
AN84 Datasheet(HTML) 1 Page - Silicon Laboratories |
|
|
1 / 26 page  Rev. 0.6 6/07 Copyright © 2007 by Silicon Laboratories AN84 AN84 DIGITAL HYBRID WITH THE Si305X DAAS 1. Introduction This application note is a guide to understanding and implementing the digital hybrid feature found in Si305x DAA products. The Si305x contains an on-chip analog hybrid that performs the 2- to 4-wire conversion and near-end echo cancellation. This hybrid circuit is adjusted for each ac termination setting selected to achieve a minimum transhybrid balance of 20 dB. The Si305x also offers a digital filter for additional near-end echo cancellation to compensate for any line impedance mismatch. For each ac termination setting, the eight programmable hybrid registers (Registers 45- 52) can be programmed with coefficients to increase the cancellation under real-world line conditions. This digital filter can produce 10 dB or greater of near-end echo cancellation in addition to the 20 dB from the analog hybrid circuitry. 1.1. Digital Hybrid Overview Figure 1 describes the basic architecture of the digital hybrid. It is composed of an 8-tap FIR filter. “b0” through “b7” represent the filter coefficients in 2s complement form. The initial 4-sample bulk delay is used to compensate for the round trip delay through the line- side device. This architecture is designed to delay and filter the transmit signal to match the portion not cancelled by the analog hybrid. Figure 1. Digital Hybrid Structure Figure 2 illustrates the basic signal flow of the DAA. The digital signal has been upsampled to 16 kHz at the digital hybrid stage. The transmit signal goes through a digital filter, digital-to-analog converter, and analog filter before going out on the line or being used in the analog hybrid circuitry. After the analog hybrid, the receive signal passes through an analog filter, analog-to-digital converter, and digital filter before going back into the digital hybrid. The analog hybrid path adds approximately four samples of delay to the signal. The digital hybrid structure matches this filter delay by delaying the digital samples by the same amount. Figure 2. Signal Flow Diagram + Z-1 Z-1 Z-4 Z-1 b 1 b 7 b 0 TX RX ADC Digital Filters Digital Filters Digital Hybrid @16kHz DAC Analog Hybrid Analog Filters AC Termination Line Driver Analog Filters Line |
Similar Part No. - AN84 |
|
Similar Description - AN84 |
|
|
|
Link URL |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link to Datasheet | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
