A fully integrated inter-stage-bandpass-filter-less direct-conversion receiver for W-CDMA

A single-chip W-CDMA direct-conversion transceiver with a low-noise amplifier (LNA) has been implemented in a 0.35-μm SiGe BiCMOS technology. Its receiver (RX) includes an LNA, a quadrature mixer (QMIX), a voltage-controlled oscillator operating at double the frequency of the carrier, a frequency divider for quadrature generation, an integer-N PLL, fifth-order elliptic low-pass filters, programmable gain amplifiers, and DC offset compensation circuits. The inter-stage bandpass filter between the LNA and QMIX has been eliminated without putting excessive demands on the duplexer. The target value of the input second-order intercept point (IIP2) was derived with the modulated transmitting signal in mind. Measurements showed that the IIP2 is at least +38.8 dBm, the noise figure is 4.9 dB, and the out-of-band IIP3 is -7.4 dBm, with no calibration or trimming. The RX draws 31 mA and the TX draws 90 mA from the 2.7 V supply. The transceiver is fully compliant with 3GPP/FDD standards.