Design of an Image-Rejection Down-Converter with Ultra-Wideband 90-Degree Phase Shifter

An image rejection mixer with an ultra-wideband 90-degree phase shifter is resented. The 90-degree phase shifter is designed by a lumped element high-pass and low-pass network. The measured conversion loss of the image rejection mixer is less than 11dB in the frequency range of 3.4-3.6GHz, the image rejection is over 20dB, and the input 1dB compression point of the mixer is about 8.5dBm. The measured EVM of single-carrier QAM-64 signal is 1.1%, which shows that an excellent modulation accuracy is achieved by the image rejection mixer.