Embodiments herein include a replica communication path and monitor circuit to provide increased common mode transient immunity. As its name suggests, the monitor circuit monitors the replica communication path and produces an adjustment signal (common mode transient adjustment signal) to cancel presence of a common mode transient signal in one or more other communication paths conveying data signals.

An amplifier, a circuit, and an optical communication system are provided. The disclosed amplifier may include a first transistor receiving a first portion of an input signal received at the amplifier, a second transistor receiving a second portion of the input signal, an automatic gain control signal that is dynamically adjustable in response to variations in an output of the amplifier, and a varactor that has its capacitance adjusted by changes in the automatic gain control signal and, as a result, adjusts a position of a pole in a transfer function of the amplifier.

An apparatus includes: first and second transistors, each of the first and second transistors includes a gate terminal, a source terminal, and a drain terminal; and a transformer including a primary winding and first and second secondary windings, the primary winding is coupled to a first input node configured to receive an input signal and a second input node configured to receive a potential, the first and second secondary windings are coupled to gate terminals of the first and second transistors and cross-coupled to source terminals of the first and second transistors.

Embodiments herein include a replica communication path and monitor circuit to provide increased common mode transient immunity. As its name suggests, the monitor circuit monitors the replica communication path and produces an adjustment signal (common mode transient adjustment signal) to cancel presence of a common mode transient signal in one or more other communication paths conveying data signals.

A preamplifier including a programmable gain amplifying circuit and a filtering circuit is provided. The programmable gain amplifying circuit has a single output terminal. The filtering circuit includes a first switched-capacitor filter and a second switched-capacitor filter. The first switched-capacitor filter is coupled to the single output terminal. The second switched-capacitor filter is connected in parallel with the first switched-capacitor filter. The first switched-capacitor filter and the second switched-capacitor filter are respectively switched between a first mode and a second mode. When the first switched-capacitor filter is switched to the first mode, the second switched-capacitor filter is switched to the second mode.

A voltage reference buffer circuit, including: an amplifier having input terminals and output terminals; a plurality of current sources coupled to the input terminals of the amplifier, the plurality of current sources including a plurality of degeneration resistors coupled to a first plurality of voltage supplies; and a degeneration resistor chopping module comprising a first and second plurality of switches coupled to the plurality of degeneration resistors.

A circuit may include first and second input nodes, first and second output nodes, first and second intermediate nodes, first and second resistances, a first amplification transistor coupled to the first input node, the first resistance, and the first intermediate node and a second amplification transistor coupled to the second input node, the second resistance, and the second intermediate node. The circuit may also include a first active device coupled to the first output node and the first intermediate node, a second active device coupled to the second output node and the second intermediate node, a first output transistor coupled to the first output node and configured to conduct based on a second intermediate signal on the second intermediate node, and a second output transistor coupled to the second output node and configured to conduct based on a first intermediate signal on the first intermediate node.

A feedback amplifier having an improved feedback network including two cross coupled switches that isolate the amplifier from extraneous undesired electrical signals present in a system or network when the amplifier is turned off (i.e., in an off-state). The cross coupled switches interconnect two feedback paths of a feedback network to enable out-of-phase differential signals to be summed and effectively canceled. Further, the feedback amplifier provides on-stage advantages to enable different amplifier characteristics and parameter to be selectively engaged by turning on or turning off certain feedback networks.

Embodiments herein include a replica communication path and monitor circuit to provide increased common mode transient immunity. As its name suggests, the monitor circuit monitors the replica communication path and produces an adjustment signal (common mode transient adjustment signal) to cancel presence of a common mode transient signal in one or more other communication paths conveying data signals.

Systems and method for improving operation of a radio frequency system are provided. One embodiment describes a radio frequency system, which includes a first switching power amplifier that outputs an amplified analog electrical signal based on a first input analog electrical signal and voltage of an envelope voltage supply rail. The first switching power amplifier includes a first transistor with a gate that receives the first input analog electrical signal, a source that is electrically coupled to the envelope voltage supply rail, and a drain that is electrically coupled to an output of the first switching power amplifier; a second transistor with a gate that receives the first input analog electrical signal, a source electrically coupled to ground, and a drain electrically coupled to the output of the first switching power amplifier; and a third transistor with a gate that receives the first input analog electrical signal, a drain electrically coupled to the envelope voltage supply rail, and a source electrically coupled to an output of a second switching power amplifier.