900MHz Image-Reject Transceivers

The MAX2420/MAX2421/MAX2422/MAX2460/MAX2463 are highly integrated front-end ICs that provide the lowest cost solution for cordless phones and ISM-band radios operating in the 900MHz band. All devices incorporate transmit and receive image-reject mixers to reduce filter cost. They operate with a +2.7V to +4.8V power supply, allowing direct connection to a three-cell battery stack.

The receive path incorporates an adjustable-gain LNA and an image-reject downconverter with 35dB image suppression. These features yield excellent combined downconverter noise figure (4dB) and high linearity with an input third-order intercept point (IP3) of up to +2dBm.

The transmitter consists of a variable-gain IF amplifier with more than 35dB control range, an image-reject upconverter with 35dB image rejection, and a power- amplifier (PA) predriver that produces up to +2dBm (in some applications serving as the final power stage).

All devices include an on-chip local oscillator (LO), requiring only an external varactor-tuned LC tank for operation. The integrated divide-by-64/65 dual-modulus prescaler can also be set to a direct mode, in which it acts as an LO buffer amplifier. Four separate power-down inputs can be used for system power management, including a 0.5µA shutdown mode. These parts are compatible with commonly used modulation schemes such as FSK, BPSK, and QPSK, as well as frequency hopping and direct sequence spread-spectrum systems. All devices come in a 28-pin SSOP package.

For applications using direct VCO or BPSK transmit modulation, as well as receive image rejection, consult the MAX2424/MAX2426 data sheet. For receive-only devices, refer to the MAX2440/MAX2441/MAX2442 data sheet.

Applications

* Cordless Phones * Spread-Spectrum Communications * Two-Way Paging * Wireless Networks * Wireless Telemetry

* Receive/Transmit Mixers with 35dB Image Rejection

* Adjustable-Gain LNA

* Up to +2dBm Combined Receiver Input IP3

* 4dB Combined Receiver Noise Figure

* >35dB of Transmit Power Control Range

* PA Predriver Provides up to +2dBm

* Low Current Consumption:

* 23mA Receive

* 26mA Transmit

* 9.5mA Oscillator

* 0.5µA Shutdown Mode

* Operates from Single +2.7V to +4.8V Supply