UAA2077TS

The UAA2077TS contains a 2 GHz front-end receiver intended to be used in mobile telephones. Designed in an advanced BiCMOS process it combines high performance with a low power consumption and high integration, thus reducing external component costs and overall front-end size.

The main advantage of the UAA2077TS is its ability to provide an image rejection over 30 dB. Therefore, an additional image filter between the Low Noise Amplifier (LNA) and the mixer is not required.Image rejection is achieved internally by two RF mixers in quadrature operation and two all-pass filters of UAA2077TS in the I and Q IF channels that shift the phase of signals by 45° and 135° respectively. These two phase shifted IF signals are combined and buffered to the front-end IF output signal.

An input signal with a frequency above the Local Oscillator (LO) frequency results in an IF signal, while an input signal
with a frequency below the LO frequency is rejected.
 
The receive section of UAA2077TS consists of an LNA that drives a quadrature mixer pair. The IF amplifier consists of an on-chip 45° and 135° phase shifting network and an image reject IF recombiner. The IF driver has differential open-collector outputs.

The LO part UAA2077TS consists of an internal all-pass phase shifting filter to provide the quadrature LO signals for the mixers of
the receive section. The all-pass filter output signals are buffered before being fed to the mixers. All RF inputs and IF outputs are balanced.

Pins RXON and SXON allow control of the different active modes and power-down. The SX mode and the RX mode of UAA2077TS are independent active states of the LO section and the receive section respectively. When the logic level on pin SXON is HIGH, all internal buffers in the LO path of the circuit are turned on, thus minimizing LO pulling during the independent powering up of the receive section. Special care of UAA2077TS has been taken by design for fast switching from power-down to any of the different active modes.