Systems and methods for providing a high performance current source are described. In an example implementation, the current source includes transistors in dual current mirror configuration. The dual mirror configuration employs current feedback to increase the output resistance of the current source while achieving a wide voltage swing.

Power supplies for electronic devices (e.g. medical imaging devices) are disclosed herein. In one embodiment, a switched mode power supply is minimized in size and weight while maintaining efficiency and an artifact-free image using power supply design techniques tailored to increasing the power conversion frequency to be above the desired receive band of an ultrasound imaging system. In another embodiment, a switched mode power supply is minimized in size and weight while maintaining efficiency and an artifact-free image using power supply design techniques tailored to increasing the power conversion frequency to be just below the desired receive band of an ultrasound imaging system causing the third harmonic and possibly the second harmonic to fall just above the desired receive band.

An electronic device may include a sensing circuit and a current subtraction circuit. The sensing circuit may output first and second current signals. The current subtraction circuit may mirror the first and second current signals onto first and second current branches. The second current branch may be split into a first sub-path and a second sub-path. An amplifier may control the amount of current flowing through the second sub-path by forcing the current flowing through the first current branch and the current flowing through the first sub-path to be identical. Configured in this way, the current flowing through the second sub-path will be equal to the difference between the first and second current signals. The current flowing through the second sub-path may be optionally amplified using another current mirror.

A circuit includes a power transistor including a first control input and first and second current terminals, the second current terminal to be coupled to a load to provide current to the load. A second transistor includes a second control input and third and fourth current terminals, and the first and second control inputs connected together and the first and third current terminals connected together. A third transistor includes a third control input and fifth and sixth current terminals. A fourth transistor includes a fourth control input and seventh and eighth current terminals, and the seventh current terminal is coupled to the fourth and fifth current terminals. An amplifier amplifies a difference between voltages on the second and fourth current terminals. An output of the amplifier is coupled to the third control input and a diode device is connected between the third and fourth control inputs.

Some aspects of the disclosure provide for a circuit. In an example, the circuit includes an amplifier, a first transistor network, a second transistor network, a first resistor, a second resistor, and a third resistor. The amplifier has first and second inputs and first, second, third, and fourth outputs. The first transistor network is coupled to the first output of the amplifier and the second output of the amplifier. The second transistor network is coupled to the third output of the amplifier and the fourth output of the amplifier. The first resistor is coupled between the first transistor network and the second transistor network. The second resistor is coupled between the first transistor network and the first input of the amplifier. The third resistor is coupled between the second transistor network and the second input of the amplifier.

A number of biasing circuits for amplifiers including voltage controlled amplifier is presented. Also a number of field effect transistor circuits include voltage controlled attenuators or voltage controlled processing circuits. Example circuits include modulators, lower distortion variable voltage controlled resistors, sine wave to triangle wave converters, and or servo controlled biasing circuits.

A voltage driver circuit for an output stage of an operational amplifier, or other circuits, includes a level shifter and an output driver including a source follower and a common source amplifier in a push-pull configuration. The level shifter generates a node voltage as a function of an input voltage on the input node. The output driver including a first transistor having a control terminal receiving the node voltage, and connected between a supply voltage and an output node, and a second transistor having a control terminal receiving the input voltage from the input node, and connected between the output node and a reference voltage, wherein the first and second transistors have a common conductivity type.

Some aspects of the disclosure provide for a circuit. In an example, the circuit includes an amplifier, a first transistor network, a second transistor network, a first resistor, a second resistor, and a third resistor. The amplifier has first and second inputs and first, second, third, and fourth outputs. The first transistor network is coupled to the first output of the amplifier and the second output of the amplifier. The second transistor network is coupled to the third output of the amplifier and the fourth output of the amplifier. The first resistor is coupled between the first transistor network and the second transistor network. The second resistor is coupled between the first transistor network and the first input of the amplifier. The third resistor is coupled between the second transistor network and the second input of the amplifier.

A circuit includes a power transistor including a first control input and first and second current terminals, the second current terminal to be coupled to a load to provide current to the load. A second transistor includes a second control input and third and fourth current terminals, and the first and second control inputs connected together and the first and third current terminals connected together. A third transistor includes a third control input and fifth and sixth current terminals. A fourth transistor includes a fourth control input and seventh and eighth current terminals, and the seventh current terminal is coupled to the fourth and fifth current terminals. An amplifier amplifies a difference between voltages on the second and fourth current terminals. An output of the amplifier is coupled to the third control input and a diode device is connected between the third and fourth control inputs.

System and method for error amplification and processing. For example, the system includes: a signal processing unit configured to receive a reference signal and a feedback signal and generate a digital pulse signal, a frequency of the digital pulse signal being associated with a difference between the reference signal and the feedback signal; a counter configured to receive the digital pulse signal and generate a counter output signal based on at least information associated with the digital pulse signal; and a digital-to-analog converter configured to receive the counter output signal and generate an output signal based on at least information associated with the counter output signal.