The MAX2557A is a complete direct-conversion RF-to-bits receiver for cdma2000® 1x/EVDO femto basestations in Band Classes 0 and 1. The device has dedicated receive paths to enable monitoring forward link activities in both bands.
The unique RF-to-bits architecture of the MAX2557A integrates four LNAs with inputs/outputs internally matched to 50W, quadrature mixers, baseband anti-aliasing filters, programmable-gain RF and baseband amplifiers, fractional-N RF synthesizer, RF VCO, fractional-N frequency synthesizer for ADC sampling clock, and high-dynamic-range I/Q continuous-time sigma-delta ADCs. The sigma-delta modulators perform I and Q analog-to-digital conversion onto 1-bit digital streams. A programmable LVDS-like interface, with its own frac-N clock generation system, is used for the data transfer to the baseband/DSP, where the final decimation, equalization, and digital channel filtering are performed in compliance with the MAX-PHY digital section definition. Digital IP
blocks are available from Maxim. The MAX2557A modes of operation are programmable by a 3-wire serial bus.
The MAX2557A is specified for operation in the extended -40°C to +85°C temperature range and is available in a 7mm x 7mm x 1.4mm fcLGA package with exposed pad (EP).
Key Features
Applications/Uses
Complete RF-to-Digital-Bits Radio Receiver Subsystem
Supports
cdma2000 1x/EVDO Band Class 0 and 1 Reverse Link
cdma2000 1x/EVDO Band Class 0 and 1 Forward Link Monitoring
TS25.104 Compliant
Compatible with UMTS1900, UMTS850, and CDMA Interference Environments
High-Dynamic-Range Continuous-Time Sigma-Delta ADCs Allow Simple AGC Implementation with Switched Gain States
MAX-PHY Digital Rx Interface with Single-Bit I/Q Bitstream, No Analog Signals
On-Chip Fractional-N Frequency Synthesizers for LO and Sampling Clock Generation
Dual-Buffered Reference Outputs to Drive Transmit IC and Baseband DSP
Programmable Rail-to-Rail GPO Pins Controlled by Serial Interface for External Component Control
Operation Controlled Entirely by 3-Wire Serial Interface, No Analog Control Signals Necessary
