Abstract: In optical receivers, extending the transimpedance amplifier's (TIA) dynamic range is a key to increasing the receiver's dynamic range, and therefore increase the channel capacity. Ideally, the TIA requires controllable gain, whereby the receiver can modify the characteristics of the TIA and/or the VGA to process high power incoming signals with a defined maximum distortion, and low power incoming signals with a defined maximum noise. A solution to the problem is to provide TIA's with reconfigurable feedback resistors, which are adjustable based on the level of power, e.g. current, generated by the photodetector, and variable load resistors, which are adjustable based on the change in impedance caused by the change in the feedback resistor.

Abstract: A dual-differential optical modulator includes two optical waveguide arms, each including one or more phase modulating p/n junctions. The p/n junctions in each waveguide arm are electrically coupled between a same pair of single-ended transmission lines so as to be differentially push-pull modulated when the transmission line pair is connected to a differential driver. Either cathode or anode electrodes of the p/n junctions are AC coupled to the transmission lines and DC biased independently on the transmission line signals.

Abstract: 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.

Abstract: A dual-differential optical modulator includes two optical waveguide arms, each including one or more phase modulating p/n junctions. The p/n junctions in each waveguide arm are electrically coupled between a same pair of single-ended transmission lines so as to be differentially push-pull modulated when the transmission line pair is connected to a differential driver. Either cathode or anode electrodes of the p/n junctions are AC coupled to the transmission lines and DC biased independently on the transmission line signals.

Abstract: A dual-differential optical modulator includes two optical waveguide arms, each including one or more phase modulating p/n junctions. The p/n junctions in each waveguide arm are electrically coupled between a same pair of single-ended transmission lines so as to be differentially push-pull modulated when the transmission line pair is connected to a differential driver. Either cathode or anode electrodes of the p/n junctions are AC coupled to the transmission lines and DC biased independently on the transmission line signals.

Abstract: Systems and methods for dynamic multitone simulation scenario planning. A method commences upon accessing a server in a circuit simulation environment to generate a multitone simulation signal to accurately simulate non-linear circuit characteristics. The tones of the multitone simulation signal are derived from a subset of possible tones based on certain properties. Some properties serve to eliminate harmonic and intermodulation products that conflict with the tones in the subset. The amplitude and phase for each tone is determined based on certain constraints. A multitone transient signal is generated from the selected tone subset and associated tone attributes to facilitate a circuit simulation. Characteristics of the multitone transient signal and/or simulation results from the circuit simulation can be analyzed to facilitate dynamically planning simulation scenarios that use multitone simulation signals.

Abstract: A circuit for blocking undesired input direct current of AC-coupled broadband circuits. The circuit includes a capacitor coupled to an input port and a common node. The input port receives a RF input signal. Additionally, the circuit includes a current source supplying a DC current to the common node leading a bias current to an output port. Further, the circuit includes a variable voltage source through an internal load and a close loop with an application circuit having an input load coupled to the output port to determine various bias voltages to control the bias current at the output port in association with a RF output signal that is substantially free of any input direct current originated from the RF input signal and is associated with an inherent low cut-off frequency independent of the various bias voltages.

Abstract: A variable gain amplifier having stabilized frequency response for widened gain control range. A resistor-capacitor compensation network is provided between two differential current input ports and corresponding emitter nodes of cross-coupled four transistors in the variable gain amplifier to desensitize the gain control voltages to the system noise and provide compensation to the VGA frequency response when the differential gain control voltage varies the gain setting, yielding a substantially stabilized frequency response over a ?3 dB bandwidth ranging from 1 GHz to 60 GHz with a widened gain control range up to 12 dB without increasing power consumption.

Abstract: The present disclosure provides a detailed description of techniques for implementing a linear amplifier with extended linear output range. More specifically, the present disclosure discloses techniques for extending the output signal range of a linear amplifier with a minimum increase in power consumption and die area consumption. Some embodiments facilitate coupling boost amplifiers with adjustable independent biasing to a main amplifier to boost the output signal near the non-linear regions of the transfer curve to extend the linear range. Certain embodiments comprise a first boost amplifier biased to contribute to the output signal when the input signal is near a negative threshold voltage, and a second boost amplifier biased to contribute to the output signal when the input signal is near a positive threshold voltage. In certain embodiments, the threshold voltages and/or the bias currents can be controlled to adjust certain amplifier attributes.

Abstract: A circuit for blocking undesired input direct current of AC-coupled broadband circuits. The circuit includes a capacitor coupled to an input port and a common node. The input port receives a RF input signal. Additionally, the circuit includes a current source supplying a DC current to the common node leading a bias current to an output port. Further, the circuit includes a variable voltage source through an internal load and a close loop with an application circuit having an input load coupled to the output port to determine various bias voltages to control the bias current at the output port in association with a RF output signal that is substantially free of any input direct current originated from the RF input signal and is associated with an inherent low cut-off frequency independent of the various bias voltages.

Abstract: A circuit for blocking undesired input direct current of AC-coupled broadband circuits. The circuit includes a capacitor coupled to an input port and a common node. The input port receives a RF input signal. Additionally, the circuit includes a current source supplying a DC current to the common node leading a bias current to an output port. Further, the circuit includes a variable voltage source through an internal load and a close loop with an application circuit having an input load coupled to the output port to determine various bias voltages to control the bias current at the output port in association with a RF output signal that is substantially free of any input direct current originated from the RF input signal and is associated with an inherent low cut-off frequency independent of the various bias voltages.

Abstract: A variable gain amplifier having stabilized frequency response for widened gain control range. A resistor-capacitor compensation network is provided between two differential current input ports and corresponding emitter nodes of cross-coupled four transistors in the variable gain amplifier to desensitize the gain control voltages to the system noise and provide compensation to the VGA frequency response when the differential gain control voltage varies the gain setting, yielding a substantially stabilized frequency response over a ?3 dB bandwidth ranging from 1 GHz to 60 GHz with a widened gain control range up to 12 dB without increasing power consumption.

Abstract: A variable gain amplifier having stabilized frequency response for widened gain control range. A resistor-capacitor compensation network is provided between two differential current input ports and corresponding emitter nodes of cross-coupled four transistors in the variable gain amplifier to desensitize the gain control voltages to the system noise and provide compensation to the VGA frequency response when the differential gain control voltage varies the gain setting, yielding a substantially stabilized frequency response over a ?3 dB bandwidth ranging from 1 GHz to 60 GHz with a widened gain control range up to 12 dB without increasing power consumption.