A communications device includes a transmission chain coupled to an antenna a receiver chain coupled to the antenna. The receiver chain includes an amplifier device having an input coupled to the antenna. A controlled switching circuit is included in the amplifier device and is operable to selectively disconnect conduction terminals of an amplifying transistor from power supply terminals when the transmission chain is operating to pass a transmit signal to the antenna.

An apparatus for detecting optical signals includes a photodetector. The photodetector is reverse-biased by a first voltage and a second voltage is added to the first voltage to provide an offset equal to the second voltage for the photodetector. A first circuit is coupled to the first circuit to provide the second voltage for the photodetector and a second circuit is coupled to the first circuit to provide the first voltage to the photodetector to reverse-bias the photodetector. The second circuit provides an output voltage proportional to a current of the photodetector at an output of the second circuit.

A low power amplifier architecture that employs a single-ended (single triode) push-pull (SEPP) vacuum tube and output transformer arrangement, and that cancels unwanted amplifier signal components such as hum and noise. The SEPP amplifier operates to cancel power supply ripple and local EMI induced noise in the output transformer by providing reverse polarity of the primary coils of the output transformer.

There is provided an amplifier module which includes a plurality of input terminals; a plurality of amplifier circuits configured to amplify a plurality of input signals which are input from each of the plurality of input terminals and output a plurality of amplified signals; and at least one speaker which is directly connected to at least one output terminals from among the plurality of amplifier circuits, wherein the amplifier module may output the plurality of amplified signals to the at least one speaker based on a number of the at least one speaker.

The embodiments described herein use resonant circuits to provide isolation between closely proximate conductors. For example, these resonant circuits can be used to reduce unwanted electromagnetic coupling and minimize crosstalk energy between package leads, bonding wires, and circuit board traces on radio frequency (RF) electronic devices, including RF power amplifiers. To facilitate a reduction in electromagnetic coupling, the resonant circuit is configured resonate with the closely proximate conductors at a selected frequency f.sub.0, and when resonating at the selected frequency f.sub.0 the resonant circuit provides a path to ground for the crosstalk energy. This path to ground reduces the crosstalk energy that would otherwise be shared between the two closely proximate conductors, and thus provides the electromagnetic isolation between the conductors.

A Doherty amplifier module includes first and second amplifier die. The first amplifier die includes one or more first power transistors configured to amplify, along a first signal path, a first input RF signal to produce an amplified first RF signal. The second amplifier die includes one or more second power transistors configured to amplify, along a second signal path, a second input RF signal to produce an amplified second RF signal. A phase shift and impedance inversion element is coupled between the outputs of the first and second amplifier die. A shunt inductance circuit is coupled to the output of either or both of the first and/or second amplifier die. Each shunt inductance circuit at least partially resonates out the output capacitance of the amplifier die to which it is connected to enable the electrical length of the phase shift and impedance inversion element to be increased.

An embodiment of a Doherty amplifier module includes a substrate, a first amplifier die, and a second amplifier die. The first amplifier die includes one or more first power transistors configured to amplify, along a first signal path, a first input RF signal to produce an amplified first RF signal. The second amplifier die includes one or more second power transistors configured to amplify, along a second signal path, a second input RF signal to produce an amplified second RF signal. The first and second amplifier die each also include an elongated output pad that is configured to enable a pluralities of wirebonds to be connected in parallel along the length of the elongated output pad so that the pluralities of wirebonds extend in perpendicular directions to the first and second signal paths.

Bypass techniques are provided herein to protect noise sensitive circuits from both internal and external noise sources. According to one embodiment, an integrated circuit (IC) chip may include a noise sensitive circuit coupled between a power supply pad and a first ground pad of the IC chip. In order to protect the first ground pad of the noise sensitive circuit, two distinct bypass paths are provided to route noise current around the noise sensitive circuit. Each bypass path terminates in its own ground pad (e.g., a second ground pad and third ground pad), which is separate from the first ground pad of the noise sensitive circuit.

A wireless power transmitter includes an amplifier configured to amplify a power; a transmitter configured to resonate the power amplified by the amplifier; and a reference signal provider configured to provide a reference signal to the amplifier and change a frequency of the reference signal.

One example includes an amplifier system. The amplifier system includes an input stage configured to receive an input pulse signal and to generate a reference voltage pulse based on the input pulse signal. The amplifier system also includes an amplifier stage that receives at least one power voltage and is configured to amplify the reference voltage pulse and to provide pulse-shaping of the amplified reference voltage pulse based on a change of amplitude of the at least one power voltage resulting from an amplitude of the reference voltage pulse.