IP2 and IP3 Nonlinearity Specifications for 3G/WCDMA Receivers

In 3G/WCDMA mobile handsets, the direct conversion receiver (DCR) architecture is commonly used due to its simplicity and low cost, where interstage filters are completely eliminated. However, with less filtering, the linearity requirement for a direct conversion receiver is very critical. It is essential to define system linearity requirements properly for the receiver to meet the performance requirements. In FDD mode, the transmitter and receiver are continuously working at the same time, and the transmitted signal leaks into the receiver due to the limited TX-to-RX isolation of the duplexer. The transmitter is possibly the strongest interferer for the companion receiver in the handset, and poses the most stringent linearity requirement for the receiver.