Demonstration circuit 844D is a 1.9GHz Direct Conversion Quadrature Demodulator featuring the LT5515. The LT®5515 is a 1.5GHz to 2.5GHz direct conversion quadrature demodulator optimized for high linearity receiver applications including PA linearization. It is suitable for communications receivers where an RF signal is directly converted into I and Q baseband signals with bandwidth up to 260MHz. The LT5515 incorporates balanced I and Q mixers, LO buffer amplifiers and a precision, high frequency quadrature generator. In an RF receiver, the high linearity of the LT5515 provides excellent spur-free dynamic range. This direct conversion receiver can eliminate the need for intermediate frequency (IF) signal processing, as well as the corresponding requirements for image filtering and IF filtering. Channel filtering can be performed directly at the outputs of the I and Q channels. These outputs can interface directly to channel- select filters (LPFs) or to a baseband amplifier. Demonstration circuit 844D is designed for operations in the frequency range between 1.7GHz and 2.2GHz and is optimized for the 1900MHz PCS band.