描述 Description

The LM97593 Dual ADC / Digital Tuner / AGC IC is a two channel digital downconverter (DDC) with integrated 12-bit analog-to-digital converters (ADCs) and automatic gain control (AGC). The LM97593 further enhances TI’s Diversity Receiver Chipset (DRCS) by integrating a wide-bandwidth dual ADC core with the DDC. The complete DRCS includes one LM97593 Dual ADC / Digital Tuner / AGC and two CLC5526 digitally controlled variable gain amplifiers (DVGAs). This system allows direct IF sampling of signals up to 300MHz for enhanced receiver performance and reduced system costs. A block diagram for a DRCS-based narrowband communications system is shown in .
The LM97593 offers high dynamic range digital tuning and filtering based on hard-wired digital signal processing (DSP) technology. Each channel has independent tuning, phase offset, filter coefficients, and gain settings. Channel filtering is performed by a series of three filters. The first is a 4-stage Cascaded Integrator Comb (CIC) filter with a programmable decimation ratio from 8 to 2048. Next there are two symmetric FIR filters, a 21-tap and a 63-tap, both with independent programmable coefficients. The first FIR filter decimates the data by 2, the second FIR decimates by either 2 or 4. Channel filter bandwidth at 52MSPS ranges from ±650kHz down to ±1.3kHz. At 65MSPS, the maximum bandwidth increases to ±812kHz.
The LM97593’s AGC controller monitors the ADC output and controls the ADC input signal level by adjusting the DVGA setting. AGC threshold, deadband+hysteresis, and the loop time constant are user defined. Total dynamic range of greater than 123dB full-scale signal to noise in a 200kHz bandwidth can be achieved with the Diversity Receiver Chipset.

特性 Features

·100% Software Compatible with the CLC5903
·Pin Compatible with the CLC5903 Except for the Analog Input and Reference Section
·123 dB Dynamic Range with CLC5526 DVGA (200kHz)
·On-chip Precision Reference
·User Programmable AGC with Enhanced Power Detector
·Channel Filters Include a Fourth Order CIC Followed by 21-tap and 63-tap Symmetric FIRs
·Flexible Output Formats
·Serial and Parallel Output Ports
·JTAG Boundary Scan
·8-bit Microprocessor Interface
·128 pin PQFP
Key Specifications ·Internal ADC Resolution: 12 Bits
·Sample Rate: 65 MSPS
·SNR (fIN = 250MHz, 11-bit, Nyquist): 62 dBFS (typ)
·SNR (fIN = 250MHz, 200kHz): 83 dBFS (typ)
·SFDR (fIN = 250MHz, 11-bit, Nyquist): 68 dBFS (typ)
·Full Power Bandwidth: 650 MHz (typ)
·Power Consumption: (65MSPS) 560 mW (typ)
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