Low-1/f-Noise Local Oscillator for Non-Overlapping Differential I/Q Signals

The present invention relates to a circuit arrangement (300) for generating non-overlapping and immune-to-1/f-noise signals as has been described. A break-before-make (BBM) circuit ensures that the differential I/Q signals (LO-0, LO-90, LO-180, LO-270), driving the transistors (M11, M12, M21, M22) of mixers (16A, 16B) in an RF receiver (200), are non-over-lapping for having at any time only one of these transistors turned on. The duty cycle of each driving signal is measured, and the difference ( ) in the duty cycle corresponding to two subsequent LO phases is determined through a respective differential amplifier (38A-38D). Each differential amplifier is configured to have a current output (LT-0, LT-90, LT-180, LT-270), which is then fed back to the input of the input buffer (30A-30D) corresponding to the first LO phase in order to adjust its logic threshold (LT) level and make the difference ( ) equal to zero. Thereby, the combined action of the BBM circuit and the feedback loops results in four non-overlapping differential I/Q signals (LO-0, LO-90, LO-180, LO-270) with constant and mutually equal duty cycles, and fixed and well-defined relative positions.