Miscellaneous active electrical nonlinear devices – circuits – and – Signal converting – shaping – or generating – Amplitude control
Reexamination Certificate
2006-08-29
2006-08-29
Wells, Kenneth B. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Signal converting, shaping, or generating
Amplitude control
C330S009000
Reexamination Certificate
active
07098716
ABSTRACT:
A DC offset cancellation circuit that is capable of canceling a DC offset voltage occurring between a pair of differential output signals of a differential amplification circuit, while preventing a signal waveform from being distorted due to accumulation of AC components and a photo-electric pulse conversion circuit that is capable of generating an electrical pulse signal that accurately reproduces a rise timing and a fall timing of an optical pulse signal by canceling the DC offset voltage are provided. A photo-electric pulse conversion circuit is provided with a photodiode, an I–V conversion circuit, a first differential amplification circuit having a DC offset cancellation circuit, a second differential amplification circuit, a reference voltage generation circuit, and a comparison circuit. The DC offset cancellation circuit uses a changeover circuit to change a state of a low-pass filter with a hold function in synchronization with an inversion electrical pulse signal, and performs a negative feedback of a filtered signal which is generated by subjecting third differential signals to low-pass filtration or a hold filtered signal which is a filtered signal held during changeover.
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Arent & Fox PLLC
Fujitsu Limited
Wells Kenneth B.
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