A Fully On-Chip, Single-Ended S-Band Image Reject Mixer for High Dynamic Range Applications

An S-band image reject downconversion mixer with high intercept point and fully integrated single-ended ports, including a UHF output, is demonstrated using GaAs pHEMT technology. The image rejection is better than 20 dB across a wide IF bandwidth ranging from 400 MHz to beyond 1 GHz with a high input IP3 of 20 dBm. On-chip passive baluns are used to provide the single-ended to differential conversion in the RF and IF paths necessary for the resistive FET mixer core. A polyphase filter is used to generate the quadrature local oscillator (LO) components, while an integrated UHF lumped element quadrature hybrid combines the intermediate frequency (IF) components to achieve image rejection fully on-chip without the need for external components.