Texas Instruments Corporation

Bharath Karthik Vasan

Srinivas Kumar Pulijala

Steven Graham Brantley

Tyler James Archer

Vadim Valerievich Ivanov

Joel Martin Halbert

Martijn Fridus Snoeij

Piyush Kaslikar

Jerry Doorenbos

YuGuo Wang

Paul G Damitio

John Lawrence Caldwell

Siva Kumar Sudani

Examples of circuits, amplifiers, and stages thereof are provided that improve amplifier stability margins while maintaining signal fidelity. Example structures include pre-driver circuitry; a compensation node exhibiting high impedance during operation; a feedforward driver coupled to the pre-driver circuitry; and first and second signal mirrors; and first and second output drivers, each having a control terminal. Example structures further include feedforward circuitry in which a first node thereof is coupled to the output of the feedforward driver, a second node thereof is coupled to the control terminal of the first output driver, and a third node thereof is coupled to the control terminal of the second output driver; and compensation circuitry in which a first node thereof is coupled to the compensation node, a second node thereof is coupled to a first internal node of the first signal mirror, and a third node thereof is coupled to a second internal node of the second signal mirror.

Frequency compensation in amplifiers with local-feedback buffer stages

In an example, a device includes a semiconductor substrate having a top surface. The device also includes a P-doped well formed in the semiconductor substrate and extending downwardly from the top surface. The device includes a cathode of a diode formed by an N-doped region in the P-doped well. The device also includes an anode of the diode formed by a P-doped region, the P-doped region spaced away from the N-doped region in the P-doped well. The device includes a deep N-type buried layer (DNBL) formed in the semiconductor substrate, the P-doped well formed between the top surface and the DNBL. The device also includes an N-doped well extending from the top surface to the DNBL.

Ultra-low leakage diodes used for low input bias current

Examples of amplifiers accurately generate control currents for control terminals of output drivers using current-replication transistors and current mirrors. An input terminal of a first current mirror is coupled to the control terminal of a first current-replication transistor, and an input terminal of a second current mirror is coupled to the control terminal of a second current-replication transistor. The output terminals of the first and second current mirrors are coupled to the control terminals of first and second output drivers, respectively. First and second intermediate currents indicative of first and second currents flowing to the first and second output driver elements, respectively, are generated. Using the first and second current mirrors, first and second control currents are generated to control the first and second output driver elements, respectively, by scaling the first and second intermediate currents according to the gain factors of the current mirrors.

Control of base currents for output driver transistors in amplifiers

Examples of amplifiers use current-replication transistors and a separation circuit coupled to such transistors to separate error current components from other current components in a pre-driver of an amplifier. In response to driving the current-replication transistors with the separated error current components, replica base current components that approximate error-modulation components of the pre-driver base currents are generated. Replica-current subtraction circuitry coupled to the current-replication transistors then subtract the replica base current components from the pre-driver base currents, affecting cancellation of the error-modulation components of the pre-driver base currents.

Control of input bias current modulation in amplifiers

A chopper amplifier circuit includes a first amplifier path, a second amplifier path, and a third amplifier path. The first amplifier path includes chopper circuitry configured to modulate an input signal and an offset voltage at a chopping frequency, and ripple reduction circuitry configured to attenuate the chopping frequency in a signal in the first amplifier path. The second amplifier path includes a feedforward gain stage, and is configured to apply higher gain to intermediate signal frequencies than is applied in the first amplifier path. The third amplifier path includes a feedforward gain stage, and is configured to apply higher gain to high signal frequencies than is applied in the first amplifier path and the second amplifier path. The intermediate signal frequencies are lower than the high signal frequencies.

Chopper amplifier

A chopper amplifier circuit includes a first amplifier path with chopper circuitry, a switched-capacitor filter, and multiple gain stages. The chopper amplifier circuit also includes a second amplifier path with a feed-forward gain stage. A chopping frequency of the chopper circuitry is greater than a threshold frequency at which the second amplifier path is used instead of the first amplifier path.

Chopper amplifier with decoupled chopping frequency and threshold frequency

In examples, a system comprises a differential amplifier coupled to a parasitic capacitor positioned between a first node and a first reference voltage source. The system comprises a buffer amplifier having an input terminal and an output terminal, the input terminal coupled to the first node and the output terminal coupled to a cancellation capacitor. The system includes a controlled current source coupled to the first node and the input terminal, the controlled current source coupled to a second reference voltage source. The system comprises a current sense circuit coupled to the cancellation capacitor and the second reference voltage source.

Differential amplifier including cancellation capacitors

A voltage-to-current converter that reduces third harmonic distortion. An amplifier includes an input stage. The input stage includes a first voltage-to-current conversion stage and a second voltage-to-current conversion stage. The first voltage-to-current conversion stage is configured to provide an input to output gain with compressive nonlinearity. The second voltage-to-current stage is cascaded with the first voltage-to-current conversion stage. An input of the second voltage-to-current stage is connected to an output of the first voltage-to-current conversion stage. The second voltage-to-current conversion stage is configured to provide an input to output gain with expansive nonlinearity.

Voltage-to-current converters

A voltage-to-current converter includes a first differential pair of transistors, a second differential pair of transistors, and a first resistor. The first differential pair of transistors includes a first transistor and a second transistor. An emitter of the first transistor is directly connected to an emitter of the second transistor. The second differential pair of transistors includes a third transistor and a fourth transistor. An emitter of the third transistor is directly connected to an emitter of the fourth transistor. The first resistor is connected to the emitter of the first transistor, the emitter of the second transistor, the emitter of the third transistor, and the emitter of the fourth transistor.

System and method for improving total harmonic distortion of an amplifier

At least some embodiments are directed to a system comprising an amplifier containing a first bias current source and configured to provide an output voltage at a node, a gain stage coupled to the node and comprising a second bias current source, and a buffer stage coupled to the node and comprising third and fourth bias current sources and an additional set of bias current sources, the third and fourth bias current sources are able to activate output transistors that are configured to increase current provided to a load. The system also comprises a controller configured to activate the first bias current source, to activate the second bias current source after the first bias current source is activated, to activate the bias current sources in the set after the first bias current source is activated, and to activate the third and fourth bias current sources after the first and second bias current sources are activated and after the bias current sources in the set are activated.

Growing community of inventors

Tucson, AZ, United States of America

Bharath Karthik Vasan