A 0.2-19GHz Zero-IF Reconfigurable Quadrature Transmitter with T-coil Matching Network

The research team proposed a 0.2-19 GHz ultra-wideband reconfigurable transmitter based on a T-coil matching network. The study is based on the analysis of T-coil matching networks and defines the design boundaries to achieve broadband voltage gain flatness. By applying the T-coil of capacitive and resistive loads to the matching networks of the mixer and the power amplifier, respectively, the transmitter is enabled to realize broadband frequency coverage. In order to achieve a high mirror rejection rate over a wideband range, and under the mutual compromise of considering phase error and power consumption, this study employs a circuit structure of two frequency dividers to generate quadrature clock signals with low phase error. Based on a feed-forward compensated transconductance amplifier, the baseband low-pass filter achieves a wide reconfigurable bandwidth and gain adjustment range. The proposed transmitter is implemented in a 28nm CMOS process and achieves a saturated output power of 8.1-13.4dBm in a compact area of 2.07mm², with a mirror rejection and a local oscillator leakage rejection better than 41dBc/38dBc, respectively.The baseband filter has a reconfigurable bandwidth range of 100MHz to 500MHz and a gain adjustment range of 20dB.

The relevant results were published in IEEE TCAS-II 2025, a top international journal on circuits and systems, with An Sun, a doctoral student at the School of Microelectronics, Fudan University, as the first author.

Paper link：A. Sun et al., A 0.2-19GHz Zero-IF Reconfigurable Quadrature Transmitter with T-coil Matching Network, in IEEE Transactions on Circuits and Systems II: Express Briefs, doi: 10.1109/TCSII.2025.3577994.