Variable-transconductance four-quadrant Gilbert-type modulator with feedback circuitry in improved NMR transmission
PSK modulation with an error correction memory
Quadrature modulator having compensation for local oscillator leak
Phaseshift network for an IQ modulator
Quadrature modulation circuit
Quadrature modulator having circuit for correcting phase error
Quadrature modulator having controlled phase shifter
Error tracking loop
Quadrature local oscillator network Patent #: 5412351
ApplicationNo. 186398 filed on 01/25/1994
US Classes:375/295, TRANSMITTERS332/103, PHASE SHIFT KEYING MODULATOR OR QUADRATURE AMPLITUDE MODULATOR375/261, Quadrature amplitude modulation375/298Quadrature amplitude modulation
ExaminersPrimary: Coles, Sr., Edward L.
Assistant: Williams, Kimberly
Attorney, Agent or Firm
International ClassesH04L 027/04
AbstractAn I/Q quadraphase modulator circuit for correcting phase errors of, typically, LO input quadrature signals. The circuit uses a pair of Gilbert cell multipliers, to the bottom ports of which are applied I and Q signals, and to the top ports of which are applied sum and difference, limited, quadrature, differential signals. The result is to make the circuit less sensitive to LO phase errors and thus to improve sideband (image) rejection over the conventional circuit typically using one Gilbert cell multiplier.