UAA2073AM

UAA2073AM contains both a receiver front-end and a high frequency transmit mixer intended for GSM (Global System for Mobile communications) cellular telephones. Designed in an advanced BiCMOS UAA2073AM process it combines high  performance with low power consumption and a high degree of integration, thus reducing external component costs and total front-end size.

The main advantage of the UAA2073AM is its ability to provide over 30 dB of image rejection. Consequently, the image filter between the LNA and the mixer is suppressed and the duplexer design is eased, compared with a conventional front-end design.

Image rejection UAA2073AM is achieved in the internal architecture by two RF mixers in quadrature and two all-pass filters in I and Q IF channels that phase shift the IF by 45° and 135° respectively. The two phase shifted IFs UAA2073AM are recombined and buffered to furnish the IF output signal.

This means that signals presented at the RF input UAA2073AM at LO - IF frequency are rejected through this signal processing while signals at LO + IF frequency can form the IF signal.The receiver section consists of a low-noise amplifier UAA2073AM that drives a quadrature mixer pair. The IF amplifier has on-chip 45° and 135° phase shifting and a combining network for image rejection.The IF driver has differential open-collector type outputs.

The LO part UAA2073AM consists of an internal all-pass type phase shifter to provide quadrature LO signals to the receive mixers. The all-pass filters outputs are buffered before being fed to the receive mixers.

The transmit section UAA2073AM consists of a down-conversion mixer and a transmit IF driver stage. In the transmit mode an internal LO buffer is used to drive the transmit IF down-conversion mixer.All RF and IF inputs or outputs are balanced to reduce EMC issues.

Fast power-up switching UAA2073AM is possible. A synthesizer-on (SX) mode enables LO buffers independent of the other circuits. When SXON pin is HIGH, all internal buffers on the LO path of the circuit are turned on, thus minimizing LO pulling when remainder of receive chain is powered-up.