Decoder circuit for phase modulated signals
First Claim
1. A decoder circuit for providing amplitude compensation for a phase modulated signal, comprising:
- inphase receive signal component of the phase modulated signal;
quadrature receive signal component of the phase modulated signal;
demodulator means for receiving the inphase receive signal and the quadrature receive signal as inputs and outputting an amplitude varying signal;
feedforward automatic gain control circuit for receiving the inphase receive signal, the quadrature receive signal and the amplitude varying signal and outputting an amplitude compensated signal;
means for detecting the inphase receive signal and the quadrature receive signal;
means for outputting a DC signal representing an amplitude of the inphase receive signal and the quadrature receive signal;
a constant current bias for offsetting said DC signal and providing a control signal; and
gain control circuit for receiving the control signal and the amplitude varying signal and outputting the amplitude compensated signal.
2 Assignments
0 Petitions
Accused Products
Abstract
A decoder circuit (21) and method for providing an amplitude compensated signal by removing the undesired effect of amplitude modulation on a phase modulated signal. The decoder method is provided by demodulating a received inphase receive signal component (10) and quadrature receive signal component (12) of the phase modulated signal and outputting an amplitude varying signal (15) to a feedforward automatic gain control circuit that outputs an amplitude compensated signal (38). The feedforward automatic gain control circuit comprises a detector circuit (16), an offset bias circuit (32), a differencer circuit (30) and a gain control circuit (28).
The detector circuit (16) outputs a DC signal (17) representing an amplitude of the inphase receive signal (10) and the quadrature receive signal (12). The offset bias circuit (32) provides a constant current bias (29) to the DC signal (17) thus creating a control signal 31. The gain control circuit (28) receives the control signal (31) and the amplitude varying signal (15) and outputs an amplitude compensated signal (38).
49 Citations
16 Claims
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1. A decoder circuit for providing amplitude compensation for a phase modulated signal, comprising:
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inphase receive signal component of the phase modulated signal; quadrature receive signal component of the phase modulated signal; demodulator means for receiving the inphase receive signal and the quadrature receive signal as inputs and outputting an amplitude varying signal; feedforward automatic gain control circuit for receiving the inphase receive signal, the quadrature receive signal and the amplitude varying signal and outputting an amplitude compensated signal; means for detecting the inphase receive signal and the quadrature receive signal; means for outputting a DC signal representing an amplitude of the inphase receive signal and the quadrature receive signal; a constant current bias for offsetting said DC signal and providing a control signal; and gain control circuit for receiving the control signal and the amplitude varying signal and outputting the amplitude compensated signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A decoder circuit for providing amplitude compensation for a phase modulated signal, comprising:
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inphase receive signal component of the phase modulated signal; quadrature receive signal component of the phase modulated signal; demodulator means for receiving the inphase receive signal and the quadrature receive signal as input and outputting an amplitude varying signal; means for detecting the inphase receive signal and the quadrature receive signal; means for outputting a DC signal representing an amplitude of the inphase receive signal and the quadrature receive signal; a constant current bias for offsetting said DC signal and providing a control signal; and gain control circuit for receiving the control signal and the amplitude varying signal and outputting an amplitude compensated signal. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A method of providing amplitude compensation for a phase modulated signal comprising the steps of:
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receiving an inphase receive signal; receiving a quadrature receive signal; demodulating by operating on the inphase receive signal and the quadrature receive signal to produce an amplitude varying signal; producing a control signal proportional to the inphase receive signal and quadrature receive signal; feeding forward the control signal to a gain control circuit; producing an amplitude compensated signal in the gain control circuit using the amplitude varying signal and the control signal as inputs; and multiplying in a Gilbert cell multiplier the control signal and the amplitude varying signal to produce the amplitude compensated signal.
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15. A method of providing amplitude compensation for a phase modulated signal, comprising the steps of:
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receiving an inphase receive signal; receiving a quadrature receive signal; demodulating the inphase receive signal and the quadrature receive signal to produce an amplitude varying signal; producing a direct current signal representing the inphase signal and the quadrature signal; offsetting the direct current signal by a constant current bias to produce a control signal; multiplying the control signal and the amplitude varying signal to produce an amplitude compensated signal. - View Dependent Claims (16)
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Specification