UAA2077BM

UAA2077BM contains both a receiver front-end and a high frequency transmit mixer intended to be used in mobile telephones. Designed in an advanced BiCMOS 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 UAA2077BM is its ability to provide over 25 dB of image rejection. Consequently, the image filter between the LNA and the mixer is suppressed.

Image rejection UAA2077BM 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 UAA2077BM are recombined and buffered to furnish the IF output signal.

For instance, signals presented at the RF input at the LO + IF frequency UAA2077BM are rejected through this signal processing while signals at the LO - IF frequency can form the IF signal. An internal switch enables the upper or lower image frequency to be rejected.
 
The receiver UAA2077BM section 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 UAA2077BM has differential open-collector type outputs.

The LO UAA2077BM part consists of an internal all-pass type phase shifter to provide quadrature LO signals to the receive mixers. The centre frequency of the phase shifter is adjustable for maximum image rejection in a given band.

The all-pass filters outputs of UAA2077BM are buffered before being fed to the receive mixers.The transmit section 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 of UAA2077BM are balanced.Pins RXON, TXON and SXON enable a selection to be made of whether to reject the upper or lower image frequency and control of the different power-down modes.Special care of UAA2077BM has been taken for fast power-up switching.