A High-Fidelity Two-Point Transmitter With Small-Sized Loop Filter and Low-Cost Quadrature Divider

A full-integrated two-point transmitter with 1-Mb/s Gaussian-frequency-shift-keying (GFSK) modulation is fabricated in 65-nm CMOS. Both a small-sized loop filter (LF) based on cascaded capacitor multiplier and an ultralow-cost radio frequency (RF) quadrature divider based on cross-coupling self-biased tristate gates, are proposed, which are fully different from the existing designs. Various linearization mechanisms are utilized in the transmitter sub-modules to ensure high fidelity. Experimental results show that the presented work accomplishes an error vector magnitude (EVM) of 1.94%, an output power up to 1.9 dBm and the out-of-band phase noise (PN) of −124 dBc/Hz at 1-MHz offset frequency, with the power dissipation of 3.75 mW from a 1.2-V supply and an active area of 0.51 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>.