The present invention concerns a system for controlling gain when time-sharing a tuner in a frequency diversity receiver. Two radio-frequency automatic gain control (RFAGC) filter capacitors are used, each capacitor corresponding to one of the currently utilized frequencies in the frequency diversity scheme. The capacitors are switched in tandem with the tuner frequency selection. This allows the capacitor associated with a tuned frequency to retain the RFAGC voltage until the tuner returns to that frequency.

An optical module includes a board including a first surface and a second surface, a light-receiving element mounted on the first surface of the board, a capacitor mounted on the first surface of the board and connected to the light-receiving element, an optical waveguide attached to the second surface of the board and configured to transmit light, and a housing that covers the board. A recess is formed in an area of the inner surface of the housing to face the capacitor.

A receiver has a differential transimpedance amplifier (4) with two inputs and two outputs. The differential transimpedance amplifier (4) provides a differential output and this is peak-detected (15, 16) to provide amplitude reference signals. The differential transimpedance amplifier output and the amplitude reference signals are fed to a differential summing amplifier (10), which provides a fully differential signal to a comparator, or to an automatic gain control circuit (5) to regulate the differential transimpedance amplifier gain. The differential summing amplifier (10) output is a fully differential signal, thereby having lower distortion for DC and burst mode receiver applications.

An apparatus is described which uses directly modulated InGaN Light-Emitting Diodes (LEDs) or InGaN lasers as the transmitters for an underwater data-communication device. The receiver uses automatic gain control to facilitate performance of the apparatus over a wide-range of distances and water turbidities.

According to one example, errors in a logical signal from a data slicer are detected and a power supply voltage is adjusted based on the detected errors.

In one example, a device includes a photodetector to generate an electrical signal in response to an optical signal and a transimpedance amplifier unit to receive the electrical signal. In one example, the transimpedance amplifier unit may include a first inverter unit, a second inverter unit coupled to the first inverter unit, and a third inverter unit coupled to the second inverter unit. In one example the third inverter unit may include a feedback resistor and a first n-type transistor in parallel to the feedback resistor, where the first n-type transistor is to provide a variable gain of the third inverter unit.

A method and system, in an optical receiver, includes receiving a first photocurrent from a first photodetector and a second photocurrent from a second photodetector; amplifying the first photocurrent with a first amplifier to provide a first output signal and the second photocurrent with a second amplifier to provide a second output signal; adjusting a frequency response of a first path the first photocurrent and a second path of the second photocurrent; and determining a difference between the adjusted first photocurrent and the adjusted second photocurrent.

Split cascode circuits include multiple cascode paths coupled between voltage supply rails. Each cascode path includes a pair of controllable switches. A feedback path is provided for at least one of the cascode circuit paths. An active load circuit may also have a split cascode structure. Multiple-stage circuits, for implementation in Trans-Impedance Amplifiers (TIAs) or analog Receive Front-End modules (RXFEs), for example, include multiple stages of split cascode circuits.

An apparatus for automatic amplifier gain setting of an optical amplifier, said apparatus comprising an optical channel counter, OCC, unit configured to detect a number of channels present in an optical transmission spectrum; a determination unit configured to determine an average power per channel calculated by dividing a measured total power of a signal input and/or signal output of the optical amplifier by the number of channels detected by said optical channel counter, OCC, unit and a gain adjustment unit configured to adjust the amplifier gain of said optical amplifier automatically depending on a calculated power difference between a predetermined desired power per channel and the determined average power per channel provided by said determination unit.

Per-port performance optimization may be provided. First, performance data may be received corresponding to each of a plurality of ports. Then it may be determined that performance of at least one of the plurality of ports can be improved based on the received performance data corresponding to the least one of the plurality of ports. Next, in response to determining that the performance of the at least one of the plurality of ports can be improved, at least one of a plurality of components may be adjusted corresponding to the at least one of the plurality of ports to improve performance of the least one of the plurality of ports.