Broadband Quadrature Mixers and I/Q Mismatch Reduction

Silicon on Sapphire technology offer several advantages over bulk CMOS and BiCMOS technologies for the design of RFICs (RF Integrated Circuits) for the System on Chip radio applications. These advantages include superior radiation hardness, improved isolation between circuits, higher efficiency amplifiers, and more bandwidth per cost. In the last few years, RFIC designers have favored are Zero-IF and Low-IF architectures for these transceivers, due to the following main advantages over heterodyne architectures: 1. Eliminates the need to filter image of the receive band for Zero-IF architectures 2. Eliminates the IF section and its components 3. In many cases eliminates the off chip filtering after the LNA These new architectures all use quadrature mixing for which the key blocks are IQ modulators and demodulator which present an additional design challenges in terms of maintaining a low error-vector magnitude (EVM). One of the primary sources of impairments of EVM in the IQ modulators & demodulators is the gain and phase I/Q imbalance. Tahoe RF proposes a unique architecture for mitigating the impairments due to the gain and phase imbalances in the IQ modulators & demodulators and provides a new calibration method without the use of digital DSP, while maintaining low power consumption.