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US 5,006,811 AGranted
Dual quadrature frequency converter
AssigneeTriQuint Semiconductor, Inc.
InventorDennis A. Kruger
Life of this patent
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Abstract
A method and apparatus for modulating or demodulating a radio frequency (RF) signal which incorporates a pair of quadrature couplers. In demodulating an RF signal, an LO signal and the RF signal are each phase shifted -90 degrees by the couplers. The RF and LO signals are mixed as are the phase-shifted RF and LO signals. Each mixed signal is low-pass filtered and the filtered signals are added thereby producing an intermediate frequency signal.
Claims9
Apparatus for demodulating a radio frequency signal comprising:
- a first quadrature coupler having an input, a first output and a second output, said first output being connected to said input via a coupled path and said second output being connected to said input via a direct path;
- means for generating a local oscillator signal on said coupler input;
- a second quadrature coupler having an input, a first output and a second output, said first output being connected to said input via a coupled path and said second output being connected to said input via a direct path;
- means for applying the radio frequency signal to said second coupler input;
- a first mixer for mixing the signals appearing on said first outputs;
- a second mixer for mixing the signals appearing on said second outputs;
- means for filtering the signals so mixed;
- and
- means for adding the filtered signals.
6 more elements
A method for demodulating a radio frequency signal comprising the steps of:
- generating a local oscillator signal;
- applying the local oscillator signal to the input of a first quadrature coupler of the type having a coupled output and a direct output;
- applying the radio frequency signal to the input of a second quadrature coupler of the type having a coupled output and a direct output;
- mixing the signals appearing on said coupled outputs;
- mixing the signals appearing on said direct outputs;
- low-pas filtering each mixed signal;
- and
- adding the mixed signals.
5 more elements
Dependencies are inferred from the claim text.