MAX2720/MAX2721 pdf,MAX2720/MA

The MAX2720/MAX2721 are low-cost, high-performance, direct QPSK modulators designed for use in wideband-CDMA and wireless local-loop (WLL) systems. Their direct-upconversion architecture reduces system cost, component count, and board space compared to devices with dual-conversion architectures.

The MAX2720/MAX2721 include an QPSK modulator, a variable gain amplifier (VGA), and a power amplifier (PA) driver. The QPSK modulator accepts differential baseband I/Q signals and directly modulates an RF carrier in the 1.7GHz to 2.1GHz range (MAX2720) or the 2.1GHz to 2.5GHz range (MAX2721). The VGA provides 35dB of output power control. The QPSK modulator's amplitude and phase balance yield 35dBc of sideband suppression and 30dBc of carrier suppression. These devices feature an LO frequency doubler that allows the external LO source to operate at half-frequency or full-frequency when disabled.

The MAX2720/MAX2721 operate from a single +2.7V to +3.3V supply and require only 77mA (MAX2720) or 86mA (MAX2721) of supply current. An additional 20mA of supply current is saved by disabling the stand-alone PA driver. A low-power shutdown mode further reduces supply current to less than 0.1µA. The device is packaged in the small 20-pin TSSOP-EP with exposed paddle to improve RF performance.