Variable signal delaying circuit, quadrature frequency converter and radio frequency tuner

• Main Authors: COWLEY NICHOLAS PAUL, SAWYER DAVID ALBERT, ISAAC ALI
• Format: Patent
• Language: English
• Published: 20.10.2009
• Subjects: AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATIONOF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES; BASIC ELECTRONIC CIRCUITRY; DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TOANOTHER; ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHICCOMMUNICATION

A variable signal delaying circuit comprising an analog delay line having a control input for controlling the variable delay. A phase detector compares the input and output signals of the delaying circuit and supplies an output signal to a charge pump and integrator. A pulse stream generating arrangement produces pulse streams of different pulse widths and pulse control logic controls a selector for selecting any one of the pulse streams. In a first mode of operation, the control logic monitors the charge pump/filter output and selects the pulse stream which minimizes change in the output. The selection is fixed and the output of the charge pump/filter is then supplied as a correction signal to the control input of the analog delay line. Such an arrangement may be used to maintain minimum phase imbalance in I and Q signal paths of a quadrature frequency converter.