900MHz Image-Reject Receivers

The MAX2440/MAX2441/MAX2442 highly integrated front-end receiver ICs provide the lowest cost solution for cordless phones and ISM-band radios operating in the 900MHz band. All devices incorporate receive image-reject mixers to reduce filter cost. They operate with a +2.7V to +4.8V power supply, allowing direct connection to a 3-cell battery stack.

The signal 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.

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. Three 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.

Evaluation kits are available for the MAX2420/ MAX2421/MAX2422. The MAX2420/MAX2421/MAX2422 are transceivers whose receive sections and pinout are identical to the MAX2440/MAX2441/MAX2442.

For complete transceiver devices, refer to the MAX2420/ MAX2421/MAX2422/MAX2460/MAX2463 and MAX2424/ MAX2426 data sheets.

Applications

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

* Receive Mixer with 35dB Image Rejection

* Adjustable-Gain LNA

* Up to +2dBm Combined Receiver Input IP3

* 4dB Combined Receiver Noise Figure

* Low Current Consumption:

* 23mA Receive

* 9.5mA Oscillator

* 0.5µA Shutdown Mode

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