Abstract: An averaging circuit apparatus comprises a rectifier having an input for receiving a high-speed error signal having, for example, a data rate of 10 Gbps. An integrator is coupled to the rectifier and has an error output for providing an averaged representation of the error signal. The averaged representation of the error signal is supplied to a Digital Signal Processor in a channel equalizer loop for equalizing a fiber-optic channel. The Digital Signal Processor executes an algorithm that sets tap coefficients of an analogue filter in response to the averaged representation of the error signal.

Abstract: An integrated circuit comprises a gain stage circuit coupled to a compensation circuit. Both the gain stage circuit and the compensation circuit respectively comprise a first current source and a second current source that are subject to the same process variations. A negative feedback circuit is used to generate a corrective current in relation to the second current source, indicative of a current that needs to flow through a load in addition to a current flowing through the second current source in order for a variable voltage to be substantially equal to a reference voltage used to drive the first and second current sources. A compensating current corresponding to the corrective current generated for the second current source is applied to the first current source to compensate for process variation in the gain stage circuit in respect to the first current source.

Abstract: A variable gain feedback amplifier circuit comprising a degenerated common emitter circuit coupled to an emitter follower circuit, an output of the emitter follower circuit being coupled to an input of the degenerated common emitter circuit via a variable feedback impedance. An automatic gain controller is coupled to the variable feedback impedance in order to reduce a closed loop gain of the variable gain feedback amplifier circuit when required. The degenerated common emitter circuit also comprises a variable emitter impedance that is also controlled by the automatic gain controller so as to counteract a lowering effect of a reduction in the variable feedback impedance on the open-loop gain of the variable gain feedback amplifier circuit.

Abstract: An Integrated Circuits (ICs) comprising a first output stage circuit and a second output stage circuit that share common input terminals and an output terminal of the first and second output stage circuits being selectably coupled between the input terminals and the output terminal in preference to the other.

Abstract: A Root Mean Square (RMS) detector circuit includes a first differential pair circuit arranged to operate in a common mode. The detector circuit also includes a compensation circuit unit having a second differential pair circuit to duplicate an unwanted base current drawn by the first differential pair circuit. The compensation circuit unit is arranged to generate an offset voltage using the duplicated base current. The compensation circuit unit also has an operational amplifier coupled to an NMOS transistor so as to generate a corrective current corresponding to the offset voltage, the corrective current being mirrored by a current mirror and provided as a compensatory current to an input of the first differential pair circuit.

Abstract: An integrated circuit comprising a first output stage circuit and a second output stage circuit that share common input terminals and an output terminal of the first and second output stage circuits being selectably coupled between the input terminals and the output terminal in preference to the other.