A quadrature signal generator using PLL technique

A monolithic quadrature signal generator is presented, using PLL technique for automatic calibration. The quadrature signal generator consists of a quadrature signal generation block and a phase control loop to calibrate quadrature signals in real-time. The phase of a phase shifter is tuned by a control current from the phase control loop. The phase error of quadrature signals is detected by two phase detectors. A charge pump generates a feedback voltage to control the phase of the phase shifter. The quadrature signal generator operates at 1.76 GHz to 2 GHz in consistent accuracy of quadrature signals in measurement. The phase error is less than 0.3/spl deg/, and the amplitude error is less than 0.062 dB over a 500 MHz sweep in simulation. The IC is fabricated in 0.5-/spl mu/m SiGe BiCMOS, packaged in MLF 20-pin, and consumes less than 13 mA from 3-V supply.