Demodulation unit and method of demodulating a quadrature
AssigneeU.S. Philips Corporation
InventorsGerardus C. M. Gielis, Rudy J. Van De Plassche
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Abstract
To demodulate a quadrature input signal (Si) (for example, frequency shift) a demodulation unit (DEM) is used, comprising a PLL (P) having a complex mixer (M) and a controlled oscillator (V). Normally, a limiter has to be used to keep the loop gain independent of the amplitude of the quadrature input signal. In the PLL, a divider (DEL) is coupled between the mixer (M) and the oscillator (V) to divide the two mixed components (Sm1, Sm2) of the quadrature signal supplied by the mixer.
Claims9
A demodulation unit for demodulating a quadrature input signal having at least two components, comprising
- a controlled oscillator for supplying a quadrature oscillator signal in dependence upon a control signal, and
- a mixer for mixing the quadrature input signal with the quadrature oscillator signal from the controlled oscillator, and for supplying at least two mixed components, comprising an in-phase component and a quadrature component, the mixer and the oscillator being incorporated in a PLL, characterized in that the PLL also comprises
- a divider for dividing the in-phase component by the quadrature component and for supplying the output signal as a control signal to the oscillator, and
- a filtering unit for filtering one or more components and/or signals.
A divider for use in a demodulation unit, characterized in that the divider is adapted to divide and in-phase component by a quadrature component and to supply the output signal as a control signal.
A method of demodulating a quadrature input signal having at least two components, wherein a quadrature oscillator signal is supplied in dependence upon a control signal, and
- the quadrature input signal is mixed with the quadrature oscillator signal, and wherein at least two mixed components are supplied, comprising an in-phase component and a quadrature component, characterized in that the method further comprises the steps of
- dividing the in-phase component by the quadrature component and supplying the output signal as a control signal for generating the oscillator signal, and
- filtering one or more components and/or signals.
Dependencies are inferred from the claim text.