A programmable gain amplifier may include: (a) a differential amplifier having first and second input terminals and first and second output terminals, the differential amplifier providing an output signal of the programmable gain amplifier across the first and second output terminals of the differential amplifier; (b) a first set of one or more resistors coupling the first output terminal of the differential amplifier to the first input terminal of the differential amplifier; (c) a second set of one or more resistors coupling the first input terminal of the differential amplifier to a first input terminal of the programmable gain amplifier; and (d) a first set of one or more switches each connected in parallel with one or more resistors in the first or second set of resistors. The first set of switches may include two or more individually programmable switches. Each of the switches may be implemented by an input-signal independent switch disclosed herein.

An OTA circuit includes a first input stage that includes a first pair of transistors having sources coupled to a reference potential and converts a differential input voltage input to gates of the first pair of transistors into a first control current, a second input stage that includes a second pair of transistors having sources coupled to the reference potential and converts the differential input voltage input to gates of the second pair of transistors into a second control current, a first output circuit that generates one output current out of the differential output currents in accordance with the first control current, and a second output circuit that generates the other output current out of the differential output currents in accordance with the second control current.

Each input channel adjusts a level of an audio signal by individual first parameters and outputs the level-adjusted audio signals to individual output routes that include bus channels. Each bus channel mixes the level-adjusted audio signals and processes the mixed audio signal by a second parameter to output to a main output. A preview channel adjusts a level of the audio signal of each of input channels by a third parameter, mixes the level-adjusted audio signals of the input channels and processes the mixed audio signal by a fourth parameter to output to a monitor output. In response to a preview instruction, the first parameter of the input channel is copied as the third parameter, and the second parameter of the bus channel is copied as the fourth parameter of the preview channel. In response to an adjustment instruction, the third or fourth parameter of the preview channel is changed.

Embodiments of circuits for use with an amplifier that includes multiple amplifier paths include a first circuit and a second circuit in parallel with the first circuit. The first circuit includes a first input coupled to a first power divider output, a first output coupled to a first amplifier path of the multiple amplifier paths, and a first adjustable phase shifter and a first attenuator series coupled between the first input and the first output. The second circuit includes a second input coupled to a second power divider output, a second output coupled to a second amplifier path of the multiple amplifier paths, and a second adjustable phase shifter coupled between the second input and the second output.

A bidirectional amplifier includes first and second ports, with a first summing node connected to the first port and a second summing node connected to the second port. First and second gain stages are connected between the first and second summing nodes, respectively, and a first node. First and second feedback stages are also connected between the first and second summing nodes, respectively, and the first node. The amplifier operates in a first mode in which an amplified version of a signal applied to the first port is provided at the second port, or a second mode in which an amplified version of a signal applied to the second port is provided at the first port. The first and second gain stages are preferably first and second common emitter cascode arrangements, and the first and second feedback stages are preferably first and second emitter followers.

There is provided a phase-switch-equipped variable amplification device including a switch including one input port and two output ports and configured to output a single-ended signal input to the one input port into one of the two output ports, a first converter coupled to the two output ports of the switch and configured to convert the single-ended signal output from the switch into a pair of differential signals having phases different from each other by 180-degree and invert phases of the pair of differential signals in response to a switching operation at the switch, a variable amplifier configured to amplify the pair of differential signals in accordance with a control voltage, and a second converter configured to convert the pair of differential signals amplified by the variable amplifier into a single-ended signal.

A transimpedance amplifier includes a variable gain circuit configured to generate a pair of complementary signals in accordance with an input signal and a reference signal. A first differential circuit of the variable gain circuit includes a first transistor including a control terminal to receive the input signal, a second transistor including a control terminal to receive the reference signal, and a variable resistance circuit including a first field effect transistor (FET) and a second FET. A first timing when a voltage of a first linearity adjustment signal input to the first FET reaches a first threshold voltage of the first FET and a second timing when a voltage of a second linearity adjustment signal input to the second FET reaches a second threshold voltage of the second FET are different from each other.

According to one embodiment, a compact low-power receiver comprises first and second analog circuits connected by a digitally controlled interface circuit. The first analog circuit has a first direct-current (DC) offset and a first common mode voltage at an output, and the second analog circuit has a second DC offset and a second common mode voltage at an input. The digitally controlled interface circuit connects the output to the input, and is configured to match the first and second DC offsets and to match the first and second common mode voltages. In one embodiment, the first analog circuit is a variable gain control transimpedance amplifier (TIA) implemented using a current mode buffer, the second analog circuit is a second-order adjustable low-pass filter, whereby a three-pole adjustable low-pass filter in the compact low-power receiver is effectively produced.

LNA circuitry includes an input node, and output node, a primary amplifier stage, a first ancillary amplifier stage, and an input gain selection switch. The primary amplifier stage is configured to provide a first gain response between a primary amplifier stage input node and a primary amplifier stage output node, wherein the primary amplifier stage input node is coupled to the input node and the primary amplifier stage output node is coupled to the output node. The first ancillary amplifier stage is configured to provide a second gain response between a first ancillary amplifier stage input node and a first ancillary amplifier stage output node, wherein the first ancillary amplifier stage output node is coupled to the primary amplifier stage output node. The input gain selection switch is coupled between the input node and the first ancillary amplifier stage input node.

Various embodiments of the present technology may comprise methods and apparatus for a track-and-hold amplifier configured to sample and amplify an analog signal. Methods and apparatus for a track-and-hold amplifier according to various aspects of the present invention may comprise an isolation circuit configured to isolate transient current in a track-and-hold capacitor during a track phase. According to various embodiments, selective activation of the isolation circuit provides a settling time that is independent of the gain of the amplifier.