UAA2077CM

UAA2077CM contains both a receiver front-end and a high frequency transmit mixer intended to be used in mobile telephones. Designed in an advanced BiCMOS UAA2077CM 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 UAA2077CM is its ability to provide over 30 dB of image rejection. Consequently, the  image filter between the LNA and the mixer is suppressed.

Image rejection of UAA2077CM 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 are recombined and buffered to furnish the IF output signal.

Signals presented at the RF input at LO + IF frequency are rejected through this signal processing while signals at LO - IF frequency can form the IF signal.

The receiver section UAA2077CM consists of a low-noise amplifier 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 UAA2077CM 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 UAA2077CM consists of a low-noise amplifier, and a down-conversion mixer. 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.

Pins RXON, TXON and SXON UAA2077CM allow to control the different power-down modes. A synthesizer-on (SX) mode enables LO buffers independent of the other circuits. When pin SXON UAA2077CM is HIGH, all internal buffers on the LO path of the circuit are turned on, thus minimizing LO pulling when remainder of the receive or transmit chain is powered up.Special care has been taken for fast power-up switching.