10-bit, 7.5Msps, Ultra-Low-Power Analog Front-End

 

Part Number	Replacement	Explanation

Description

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The MAX19705 is an ultra-low-power, mixed-signal analog front-end (AFE) designed for power-sensitive communication equipment. Optimized for high dynamic performance at ultra-low power, the device integrates a dual 10-bit, 7.5Msps receive (Rx) ADC; dual 10-bit, 7.5Msps transmit (Tx) DAC; three fast-settling 12-bit aux-DAC channels for ancillary RF front-end control; and a 10-bit, 333ksps housekeeping aux-ADC. The typical operating power in Tx-Rx FAST mode is 28.2mW at a 7.5MHz clock frequency.

The Rx ADCs feature 55.1dB SNR and 73.4dBc SFDR at a 1.875MHz input frequency with a 7.5MHz clock frequency. The analog I/Q input amplifiers are fully differential and accept 1.024V_P-P full-scale signals. Typical I/Q channel matching is ±0.01° phase and ±0.02dB gain.

The Tx DACs feature 77.2dBc SFDR at f_OUT = 620kHz and f_CLK = 7.5MHz. The analog I/Q full-scale output voltage is ±400mV differential. The Tx DAC commonmode DC level is programmable from 0.9V to 1.35V. The I/Q channel offset is adjustable. The typical I/Q channel matching is ±0.03dB gain and ±0.08° phase.

The Rx ADC and Tx DAC share a single, 10-bit parallel, high-speed digital bus allowing half-duplex operation for time-division duplex (TDD) applications. A 3-wire serial interface controls power-management modes, the aux-DAC channels, and the aux-ADC channels.

The MAX19705 operates on a single +2.7V to +3.3V analog supply and +1.8V to +3.3V digital I/O supply. The MAX19705 is specified for the extended (-40°C to +85°C) temperature range and is available in a 48-pin, thin QFN package. See a parametric table of the complete family of pin-compatible AFEs.

MAX19705: Functional Diagram Enlarge+

Key Features

Dual 10-Bit, 7.5Msps Rx ADC and Dual 10-Bit, 7.5Msps Tx DAC

Ultra-Low Power

28.2mW at f_CLK = 7.5MHz, Fast Mode

21mW at f_CLK = 7.5MHz, Slow Mode

Low-Current Standby and Shutdown Modes

Programmable Tx DAC Common-Mode DC Level and I/Q Offset Trim

Excellent Dynamic Performance

SNR = 55.1dB at f_IN = 1.875MHz (Rx ADC)

SFDR = 77.2dBc at f_OUT = 620kHz (Tx DAC)

Three 12-Bit, 1µs Aux-DACs

10-Bit, 333ksps Aux-ADC with 4:1 Input Mux and Data Averaging

Excellent Gain/Phase Match

±0.01° Phase, ±0.02dB Gain (Rx ADC) at

f_IN = 1.875MHz

Multiplexed Parallel Digital I/O

Serial-Interface Control

Versatile Power-Control Circuits Shutdown, Standby, Idle, Tx/Rx Disable

Miniature 48-Pin Thin QFN Package (7mm x 7mm x 0.8mm)

Applications/Uses

• Broadband Access Radio
• Portable Communication Equipment
• Private Mobile Radio (PMR)