Design of Wideband Phase Modulator for 2.4~5.25 GHz Digital Polar Transmitter

Abstract

This paper presents a wideband phase modulator for 2.4~5.25GHz digital polar transmitter implemented in 22 nm CMOS process. The phase modulator is an open-loop phase modulation architecture for wide bandwidth, and modulates the output phase according to the principle of vector-sum. The core circuit of the phase modulator is a high-resolution I/Q phase interpolator (PI), which achieves phase modulation by the weighted summation of in-phase (I) and quadrature (Q) signals. Differential-current DACs are used to implement the I/Q weighting. The simulation results show that in the range of 2.4~5.25GHz, the power consumption is 11mW, the phase resolution is 0.7°, and the operating temperature covers -40~85℃.