A wide-band, compact, fully differential & amp; highly accurate integrated phase quadrature locked loop on 0.18 µm CMOS

A highly accurate phase quadrature locked loop (IQPLL) has been developed on a 0.18µm CMOS process. From two differential signals provided by a local oscillator LO, whose phases are roughly in quadrature, the IQPLL circuit generates accurate 0, 90, 180 & 270° phase shifted square signals. For the full 900-2300MHz frequency range, IQPLL achieves an output quadrature phase error of less than 0.25° for an input quadrature phase error of at least ±15°. IQPLL is completely integrated (including voltage and current references), features 0.08mm²and consumes 15.8mW at 1.8V, which is mainly due to the 2.3GHz CML cells. When implemented after the local oscillator, within the IQPLL bandwidth this circuit also improves the total output phase noise by 3dB on each output signal, and the differential phase noise is rejected by 20dB/decade.