A method for removing offset in a receiver of an integrated circuit (IC) includes: determining digital codes of differential input voltages of an amplifier in a first receiving lane of the receiver; comparing the digital codes to a digital code corresponding to an optimum common mode voltage (VCM) of the receiver; according to the comparison, determining a bias code for adjusting both the differential input voltages to match the optimum VCM; and inputting the bias code to a bias circuit of the receiver. The first receiving lane of the receiver includes a plurality of amplifiers. The method steps are repeated for each amplifier of the plurality of amplifiers, and then repeated for all receiving lanes of the IC.

An optical receiver includes a photodiode, a transimpedance amplifier (TIA), a slope detection circuit, and a logic circuit. The TIA includes an output stage and a feedback amplifier and is coupled to the photodiode. The slope detection circuit is coupled to the feedback amplifier and configured to monitor a feedback signal from the feedback amplifier. The slope detection circuit is configured to provide, in response to a slope in the feedback signal being detected, a first slope-status signal indicating the slope is detected. The logic circuit is coupled to the slope detection circuit and is coupled to the output stage of the TIA. The logic circuit is configured to squelch the output stage of the TIA in response to the first slope-status signal.

An optical receiver capable of substantially measuring the phase and amplitude of a received intensity- or amplitude-modulated optical signal by performing digital-signal processing. In an example embodiment, a DSP of the receiver operates to reduce the detrimental effects of relative phase noise between the optical reference oscillator and optical carrier based on an optical pilot present in the received optical signal. The DSP may employ a sequence of digital filters configured to select a signal component that represents a non-vestigial modulation sideband and then perform signal equalization thereon. The signal equalization may include but is not limited to dispersion compensation. In some embodiments, the optical receiver can be a direct-detection optical receiver. In an example embodiment, the optical reference oscillator and optical carrier are generated using two respective independently running lasers that may or may not be co-located.

In optical receivers, cancelling the DC component of the incoming current is a key to increasing the receiver's effectiveness, and therefore increase the channel capacity. Ideally, the receiver includes a DC cancellation circuit for removing the DC component; however, in differential receivers an offset may be created between the output voltage components caused by the various amplifiers. Accordingly, an offset cancellation circuit is required to determine the offset and to modify the DC cancellation circuit accordingly.

A mobile visible light communication (VLC) receiver and associated method of use which overcomes the detrimental effects of the time-varying inter-symbol interference (ISI) due to the VLC receiver's high acceptance angle and vibration in the structure utilizing an optimal multiple-symbol detection (MSD) module and a decision feedback affine projection algorithm (DF-APA) module.

A circuit controls a dynamic time constant to remove DC offset from a received optical data signal. The circuit has a first capacitor coupled between a first terminal and a second terminal. A first resistance network is coupled between the second terminal and a reference voltage. A control circuit has a first output coupled to a control input of the first resistance network. The control circuit monotonically increases an effective resistance of the first resistance network to increase the dynamic time constant. The first resistance network has a resistor coupled to the second terminal, and a transistor with a first conduction terminal coupled to the resistor, a second conduction terminal coupled to the reference voltage, and a control terminal coupled to the first output of the control circuit. The first capacitor has a variable capacitance. The monotonic increase in the dynamic time constant can be linear or non-linear.

A circuit controls a dynamic time constant to remove DC offset from a received optical data signal. The circuit has a first capacitor coupled between a first terminal and a second terminal. A first resistance network is coupled between the second terminal and a reference voltage. A control circuit has a first output coupled to a control input of the first resistance network. The control circuit monotonically increases an effective resistance of the first resistance network to increase the dynamic time constant. The first resistance network has a resistor coupled to the second terminal, and a transistor with a first conduction terminal coupled to the resistor, a second conduction terminal coupled to the reference voltage, and a control terminal coupled to the first output of the control circuit. The first capacitor has a variable capacitance. The monotonic increase in the dynamic time constant can be linear or non-linear.

Techniques for autozero to an offset value for a slope detector for voltage droop monitoring are described herein. An aspect includes generating a first offset voltage by a circuit. Another aspect includes generating a second offset voltage by the circuit, the second offset voltage being distinct from the first offset voltage. Another aspect includes, based on a first comparator of the circuit entering an autozero mode, connecting a first terminal of the first comparator to the first offset voltage. Another aspect includes connecting a second terminal of the first comparator to the second offset voltage. Yet another aspect includes performing an autozero operation in the first comparator, wherein a trip point of the first comparator is set to a difference between the first offset voltage and the second offset voltage by the autozero operation.

In optical receivers, cancelling the DC component of the incoming current is a key to increasing the receiver's effectiveness, and therefore increase the channel capacity. Ideally, the receiver includes a DC cancellation circuit for removing the DC component; however, in differential receivers an offset may be created between the output voltage components caused by the various amplifiers. Accordingly, an offset cancellation circuit is required to determine the offset and to modify the DC cancellation circuit accordingly.

An optical receiver (1) comprises a differential TIA (4) linked with a photodiode (2, 3) providing a current sense signal (I.sub.sig_tia). The receiver is configured to provide to the TIA a sense signal as a sense TIA input (I.sub.sig_tia) and a second input (I.sub.dark_tia) which is a proportion of the maximum sense signal. The proportion input is half of said maximum sense signal. The inputs to the TIA are via cascode circuits (5, 6), thereby providing the advantages of a low input impedance for large area photodiodes at the TIA input, while creating a fully differential signal at the output, and the reduction of TIA bandwidth in burst mode applications, which filters out high frequency noise.