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An active balun using current steering topology is presented for phase and amplitude corrections. The proposed active balun is constructed with two different unit balun structures based on resistive feedback to reduce phase and amplitude errors. The first unit balun composed of the common source configuration provides a main transconductance stage for the proposed active balun. The second unit balun using common source and common gate configurations works for phase and gain error reduction. The resistive feedback proposed here leads to mitigation of phase error and then amplitude error, and an equation for deciding the feedback resistance is successfully deduced. The value of a feedback resistor is determined to provide the least phase and amplitude errors by optimizing the derived design equation. Designed and fabricated active balun in 65 nm CMOS process operates over 1.0–1.2 GHz band, showing input and output reflection coefficients under –10 dB, phase error under 3.5° and gain error under 1.4 dB over the frequency of interest. Moreover, the gain is measured to be 4 dB maximum and power consumption of 2.6 mW is measured.

This article introduces a direct‐conversion CMOS RF transmitter for the IEEE 802.15.4 standard with a low‐power high‐gain up‐conversion mixer designed in 0.18 μm process. The designed RF direct‐conversion transmitter (DCT) is composed of differential digital to analog converter, passive lowpass filter, quadrature active mixer, and drive amplifier. The most important characteristic in designing RF DCT is to satisfy the 2.4 GHz Zigbee standard in a low power consumption. The quadrature active mixer integrated in the proposed RF DCT provides enough high gain as well as sufficient linearity using a gain boosting technique. The measurement results for the proposed transmitter show very low power consumption of 7.8 mA, output power more than 0 dBm, and adjacent channel power ratio of −30 dBc.

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