Abstract: An optical transceiver with a transimpedance amplifier generates a dynamic common mode voltage of the peak-to-peak output current of the photodetector for use as an in-situ optical power meter. Peak-to-peak voltage signal are imposed on the common mode voltage so optical power measurements are obtained using preexisting electrical contacts. An nfet and a capacitor of the transimpedance amplifier smooths the peak-to-peak voltage to create the control signal for the common mode voltage. The common mode current is mirrored into a bank of pfets at the output stage to create a current sink. Depending upon the potential of the common mode voltage, more or less current will be drawn from the peak-to-peak voltage signals output from a final differential amplifier stage of the transimpedance amplifier.

Abstract: An optical transceiver having a transimpedance amplifier with an in-situ optical power meter is disclosed which realizes that the common mode voltage of a peak-to-peak voltage signal derived from impinging light is related to the optical power of the impinging light. The peak-to-peak voltage signals, moreover, can be imposed on the common mode voltage so that the optical power measurements can be derived with existing electrical contacts. In the preferred embodiment, the optical power meter takes advantage of certain functions within a transimpedance amplifier of the optical receiver. First, the use of an nfet and a capacitor smooth the peak-to-peak voltage to create the control signal for the common mode voltage. Then the common mode current is mirrored into a bank of pfets at the output stage to create a current sink.

Abstract: An improved laser diode driving circuit is disclosed which includes a current source, an operational amplifier, a light sensing device, a current mirror, and a constant current source. The current source is coupled to the laser diode for biasing the laser diode. The operational amplifier has an output coupled to the current source for driving the current source. The operational amplifier includes a first and a second input. The first input is coupled to a reference voltage. The second input receives a feedback signal. The light sensing device is coupled to a first supply voltage for detecting a portion of an optical power output from the laser. The light sensing device generates a monitor current proportional to the detected optical power output. The current mirror is coupled to the light sensing device and the second input of the operational amplifier. The current mirror receives the monitor current and generates a mirror current which is substantially equal to the monitor current.

Abstract: A redundant resistor matching detector is provided with constant percentage threshold. The redundant resistor matching detector includes a voltage reference and a first operational amplifier, a second operational amplifier, a first potentiometer and a reference potentiometer. The first operational amplifier has a first input connected to a first potentiometer. The second operational amplifier has a first input connected to the reference potentiometer. The first operational amplifier and the second operational amplifier have a reference input coupled to the voltage reference. An input current mirror is coupled to the first potentiometer providing a first current. A first reference current mirror is coupled to the reference potentiometer providing a reference current. A second reference current mirror has an input coupled to a first output of the first reference current mirror and has a first output coupled to an output of the input current mirror.

Abstract: A improved signal detector is provided. The signal detector includes a linear amplifier receiving the input signal and providing an amplified signal. A full-wave rectifier is coupled to the linear amplifier and provides a rectified signal. A low-pass filter is coupled to the full-wave rectifier receiving the rectified signal and providing a comparing signal. A high threshold reference and a low threshold reference respectively is applied to a first comparator and a second comparator, each receiving the comparing signal. The first comparator and the second comparator respectively provide a first compared signal and a second compared signal. A reference path providing the high threshold reference and the low threshold reference includes a linear amplifier, a full-wave rectifier and a low-pass filter providing the high threshold reference. A linear charge pump is connected at its input to the linear amplifier and connected at its output to a low-pass filter to provide the low threshold reference.

Abstract: A linear phase detector used with half-speed quadrature clock architecture is provided. The linear phase detector includes a first circuit receiving a data signal, a first half-speed quadrature clock signal and a second half-speed quadrature clock signal. The first circuit generates an adjusted data signal and a polarity representing signal of the first half-speed quadrature clock signal. A high speed phase detector is coupled to the first circuit for generating a linear phase correction signal.