L64724 LSI Logic Corporation, L64724 Datasheet - Page 135

• Manufacturer Part Number: L64724
• Description: Satellite Receiver
• Manufacturer: LSI Logic Corporation

5.3 DC Offset Compensation and Coupling to ADC Output
The internal ADC produces six-bit samples that digitize the analog data
streams into 64 discrete values, as shown in
Figure 5.2
The L64724 provides for an internal suppression of DC offsets on the
I and Q channels.
The suppression feature is particularly useful when using an integrated
front end that does not provide DC offset compensation pins and that
introduces small offsets. DC offset compensation is controlled with the
DC_Offset_On_Off[1:0] bits (see Group 4, APR 23). The DC offset
compensation can be accomplished with or without noise feedback,
whichever best optimizes BER. Noise feedback essentially shapes the
quantization error spectrum.
Back end DC offset compensation (after the matched filter) is also
provided and can be used if necessary. To enable this function, set the
INT_DC bit to 1 (Group 4, APR 25).
DC Offset Compensation and Coupling to ADC Output
Input Quantization
2
3
1
ADC Output
3
1
2
ADC
Input
Figure
5.2.
5-3