A linear amplifier is provided to have higher efficiency for an envelope tracking modulator. In one embodiment, a first stage amplifier circuit can be simply operated in a high gain mode or a high bandwidth mode for different applications, without using large chip area. In another embodiment, an output stage has a cascode structure whose dynamic range is controlled according to a voltage level of a supply voltage, to make a core device within the output stage have better protection and suitable dynamic range.

Aspects of the present disclosure provide for a system. In at least some examples, the system includes an embedded Universal Serial Bus 2 (eUSB2) device having a first receiver and a first transmitter, a processor, a second transmitter coupled to the processor, a second receiver coupled to the processor, a drive low circuit coupled to the processor second transmitter, and differential signal lines having a length greater than ten inches. The differential signal lines are coupled at a first end to the first receiver and the first transmitter and at a second end to the second transmitter and the second receiver. The processor is configured to control the drive low circuit to drive the differential signal lines low with a logic 0 to cause the first receiver to receive the logic 0 and a value of a signal present on the differential signal lines to reach about 0 volts.

In one general aspect, an amplifier can include an input amplifier circuit configured to receive a bias current and receive, as an input, a signal pair connected differentially to the input amplifier circuit, the input amplifier circuit configured to output a differential output signal pair based on the received differential input signal pair, a feedback amplifier circuit configured to receive an average of the differential output signal pair and configured to provide a bias setting output for controlling the bias current, and an output buffer circuit configured to buffer the differential output signal pair, the buffering resulting in a buffered differential output signal pair capable of driving a resistive load.

In one general aspect, an amplifier can include an input amplifier circuit configured to receive a bias current and receive, as an input, a signal pair connected differentially to the input amplifier circuit, the input amplifier circuit configured to output a differential output signal pair based on the received differential input signal pair, a feedback amplifier circuit configured to receive an average of the differential output signal pair and configured to provide a bias setting output for controlling the bias current, and an output buffer circuit configured to buffer the differential output signal pair, the buffering resulting in a buffered differential output signal pair capable of driving a resistive load.

A variable current trans-impedance amplifier (TIA) for an ultrasound device is described. The TIA may be coupled to an ultrasonic transducer to amplify an output signal of the ultrasonic transducer representing an ultrasound signal received by the ultrasonic transducer. During acquisition of the ultrasound signal by the ultrasonic transducer, one or more current sources in the TIA may be varied.

A dynamic amplifier with a bypass design. An input pair of transistors receives a pair of differential inputs Vip and Vin and further provides first, second and third terminals. A load circuit provides a pair of differential outputs Vop and Von with the load circuit connected at a common mode terminal. In an amplification phase, a driver for amplification is coupled to the first terminal and the load circuit is coupled to the second and third terminals. A bypassing circuit is specifically provided. The bypassing circuit is coupled to the second and third terminals during a bypass period within the amplification phase.

In one general aspect, an amplifier can include an input amplifier circuit configured to receive a bias current and receive, as an input, a signal pair connected differentially to the input amplifier circuit, the input amplifier circuit configured to output a differential output signal pair based on the received differential input signal pair, a feedback amplifier circuit configured to receive an average of the differential output signal pair and configured to provide a bias setting output for controlling the bias current, and an output buffer circuit configured to buffer the differential output signal pair, the buffering resulting in a buffered differential output signal pair capable of driving a resistive load.

A transmitter circuit is provided. The transmitter circuit has a first transmission node and a second transmission node and includes a first resistor, a second resistor, a third resistor, a fourth resistor, and a driving circuit. The driving circuit includes a first transistor group, a second transistor group, a third transistor group, and a fourth transistor group. The first resistor is coupled between a first output terminal and the first transmission node. The second resistor is coupled between a second output terminal and the second transmission node. The third resistor is coupled between a third output terminal and the first transmission node. The fourth resistor is coupled between a fourth output terminal and the second transmission node. The first, second, third, and fourth transistor groups are coupled to a first and a second reference voltages and electrically connected to the first, second, third, and fourth output terminals, respectively.

In circuitry to capture differences between magnitudes of first and second comparator input signals in capture operations defined by a clock signal, first and second nodes are connectable to a tail node receiving a clock-signal-independent bias current along first and second paths. During each capture operation, switching circuitry controls connections between the tail node and the first and second nodes based on the input signals to divide the bias current between the first and second paths depending on the input signal magnitude difference. The switching circuitry comprises first and second transistors arranged such that conductivity of connections between the tail node and the first and second nodes is controlled by the magnitudes of the input signals, and third and fourth non-clocked transistors controlled by a clock-signal independent gate bias signal.

A resistor in a pair of resistors is selectively coupled to a current source through a selection switch during the reset phase of a voltage-mode sense amplifier so that one evaluation node for the voltage-mode sense amplifier is discharged from a power supply voltage by an ohmic voltage drop across the selectively-coupled resistor to null an offset for the voltage-mode sense amplifier.