An Intuitive Current-Driven Passive Mixer Model Based on Switched-Capacitor Theory

An intuitive current-driven passive mixer model is presented. Without using complex math, it provides a signal-transfer-function/noise description of a passive mixer when used in a wireless receiver (RX) chain driven by a transconductor and loaded by a low-pass baseband (BB). Exploiting a switched-capacitor approach, the model represents a useful tool for simple hand analysis and design. The case of a 25%-duty-cycle quadrature RX chain based on a transimpedance amplifier at BB is analyzed in detail and compared with simulations, showing good accuracy.