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Kfrequency tracking system using a digital correlator

Patent Number: 7679468
Publication Date: 2010-03-16
Inventors: Groe, John B.; Walley, Kenneth Scott

An apparatus for providing a two point phase/frequency modulation system is disclosed herein. The apparatus includes a first network configured to introduce an offset to center a signal applied to a VCO. The apparatus further includes a second network configured to set a gain of the VCO. A phase tracking network is configured to dynamically adjust the offset and the ...

Linear wideband phase modulation system

Patent Number: 7675379
Publication Date: 2010-03-09
Inventor: Groe, John B.

Linear wideband phase modulation system. Apparatus is provided for linear phase modulation utilizing a phase-locked loop. The apparatus includes a limiting circuit that restricts a range of a modulation signal that is coupled to a voltage controlled oscillator (VCO) associated with the phase-locked loop, and a linearizing circuit that reshapes the modulation signal to improve ...

Apparatus and method for compensating carrier feedthrough in quadrature modulation system

Patent Number: 7671692
Publication Date: 2010-03-02
Inventors: Kim, Joon Hyung; Kwon, Heon Kook; Kang, Byung Su; Lee, Kwang Chun

The present invention relates to an apparatus and a method for compensating carrier feedthrough in a quadrature modulation system. In order to suppress the carrier feedthrough, and minimize and compensate the carrier feedthrough, differences of baseband differential input DC voltages in an in-phase as well as a quadrature-phase are simultaneously adjusted to 0 or a certain slight voltage difference by a simple analog circuit. Therefore, it is possible to suppress carrier feedthrough using a ...

Quadrature modulator with phase controller apparatus and error detector

Patent Number: 7671691
Publication Date: 2010-03-02
Inventors: Shiratsuchi, Satoru; Fujinuma, Kazuhiro; Yamaguchi, Kazuhiko

A quadrature modulator divides a first signal input as a local signal into an I channel signal and a Q channel signal orthogonal to each other and outputs a second signal having a desired phase delay corresponding to direct current voltages as for the first signal by giving the direct current voltages Vi and Vq to the I channel signal and the Q channel signal, respectively. A phase comparison unit detects a phase difference θ between the first signal and the second signal. A setting unit ...

Frequency modulator using PLL

Patent Number: 7667553
Publication Date: 2010-02-23
Inventor: Sagara, Takeshi

In a frequency modulator, a VCO oscillates at a frequency according to a voltage applied to an input terminal. A divider divides an output signal of the VCO. A phase comparator compares the output of the divider with a reference clock signal and outputs a voltage corresponding to a phase difference. A loop filter is provided on a path leading from an output terminal of the phase comparator to the input terminal of the VCO, and the loop filter removes a high-frequency component of an output ...

Discrete dithered frequency pulse width modulation

Patent Number: 7667552
Publication Date: 2010-02-23
Inventors: Geng, Xin; Midya, Pallab

A system is described for generating a discrete noise-shaped variable switching frequency signal that may be used to define a digital pulse width modulation (“PWM”) period. The system may define a switching frequency waveform that may be used to generate a current switching frequency signal as a function of a system clock. The system may quantize the current switching frequency signal to generate a discrete switching frequency signal that is realizable with the system clock. The system ...

Frequency shift keying modulator having sigma-delta modulated phase rotator

Patent Number: 7667551
Publication Date: 2010-02-23
Inventors: Liu, Yao-Hong; Lin, Tsung-Hsin

A frequency shift keying modulator having sigma-delta modulated phase rotator is disclosed, which includes a phase-locked loop for generating a voltage-controlled signal; a multi-phase generator for receiving the voltage-controlled signal and generating N phase-shift signals having same frequency according to the voltage-controlled signal, the N phase-shift signals having a same phase shift between the phase-shift signals adjacent to each other; a sigma-delta modulator for receiving ...