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公开(公告)号：CA2311434C
公开(公告)日：2004-10-19
申请号：CA2311434
申请日：2000-06-13
Applicant: IBM CANADA
Inventor： FENG KAI D , HARTLEY LEE F
IPC: H03F3/08 , H03K17/785 , H04B10/06 , H04B10/14
Abstract: A photoelectric receiver circuit provides a symmetrical sensor having a transimpedance amplifier on each side of the PIN diode, the outputs of the transimpedance amplifiers being AC coupled to a differential post amplifier. The differential structure provide s a very high common noise voltage rejection ratio and a virtual ground to the inverting inputs of the transimpedance amplifiers. In the preferred embodiment a differential PIN diode bias voltage is established by separate bias voltages respectively applied to the non-inverting input of each transimpedance amplifier. Thus, a low-noise voltage regulator can be used to supply power to the bias voltages in the invention, and the AC coupling capacitors can be very small to conserve space on the chip die. Auxiliary DC currents applied to both sides of the PIN diode maintain the PIN diode bias as high as possible and maximize the output swing ranges of the transimpedance amplifiers in order t o retain a wide bandwidth. The DC current sources allow the output bias voltages of the transimpedance amplifiers to be adjusted, and when controlled by the transimpedance amplifier outputs through a low pass filter, the output bias offset caused by ambient light can be eliminated. Th e feedback resistors may be variable resistors to provide automatic gain control.
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公开(公告)号：CA2312516A1
公开(公告)日：2001-12-27
申请号：CA2312516
申请日：2000-06-27
Applicant: IBM CANADA
Inventor： FENG KAI D
Abstract: An IR transceiver having a receiver chain with an isolated analog output, provides a transmission gate and unity gain buffer interposed between the amplifier output and an analog output pad. The transmission gate behaves as a switch, passing the analog output signal to the analog output pad only when an analog output is required. The unity gain buffer has a high input resistance, a low input capacitance, a unit gain and a low output impedance, so that the load of a DSP device or measuring instrument on the analog output pad is isolated and does not affec t the performance of the receiver chain. Since the transfer rates of the transmission gate and the buffer are each a unity, the analog output pad provides a high fidelity analog output signal to the outpu t buffer.
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公开(公告)号：CA2311435A1
公开(公告)日：2001-12-13
申请号：CA2311435
申请日：2000-06-13
Applicant: IBM CANADA
Inventor： FENG KAI D
Abstract: A high efficiency LED driver circuit utilizing a capacitor to regulate the L ED driving current. The voltage across the capacitor is monitored to maintain a preselected low threshold voltage on the capacitor, which determines the LED optical emission intensity. The capacito r provides the LED driver current by discharging through the LED during transmission intervals, and the power supply for the device is used only to maintain the capacitor charge level. The LED driver circuit of the invention accordingly operates at high efficiency with low power consumption . The LED driver current can be regulated by changing the low and high threshold voltages of the capacitor pump controller, to thus control the optical intensity of the LED.
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14.发明专利
公开(公告)号：CA2311433A1
公开(公告)日：2001-12-13
申请号：CA2311433
申请日：2000-06-13
Applicant: IBM CANADA
Inventor： FENG KAI D
Abstract: An optical receiver circuit comprising a plurality of PIN diodes, each associated with a dedicated element transimpedance amplifier, the outputs of the element transimpedance amplifiers being connected to a summing amplifier which sums the voltages output from t he element transimpedance amplifiers. The circuit of the invention provides the same output voltage value as a single large PIN diode having an active area comparable to the sum of the active areas of the smaller PIN diodes, and thus has the same high sensitivity as the single lar ge PIN diode but a much wider bandwidth.
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