CMOS Active Transformers
This chapter presents the principles, characteristics, and implementation of CMOSactive transformers. Section 3.1 deals with the configurations of lossless gyrator-C active transformers where only the capacitor load of the transconductors synthesizing active transformers is considered. Both single-ended and floating lossless active transformers are investigated. The self and mutual inductances of the primary and secondary windings of lossless active transformers are investigated in detail. The configurations of gyrator-C active transformers with multiple windings are also developed. Lossy gyrator-C active transformers are developed with the consideration of both the resistive and capacitive loads of transconductors. The intrinsic relations between the self and mutual inductances are derived. Section 3.2 investigates the critical figure-or-merits that quantify the performance of active transformers. These figure-of-merits include stability, frequency range, inductance tunability, turn ratio, coupling factor, voltage and current transfer characteristics, impedance transformation, noise, quality factor, linearity, supply voltage sensitivity, parameter sensitivity, and power consumption. Section 3.3 looks into the circuit implementation of several CMOS active transformers and examines their characteristics. The chapter is summarized in Section 3.4.
KeywordsInternal Node Active Inductor Active Transformer Voltage Swing Coupling Network
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