Telasic Communications, Inc.

Telasic Communication, Inc.

Christopher B Langit

Lloyd Frederick Linder

Erick M Hirata

Roger N Kosaka

Don C Devendorf

A digitally trimmed current source. The novel current source includes a first circuit for generating a current in response to an applied voltage and a resistance variable in response to a control signal, and a second circuit for supplying the control signal. The first circuit includes a resistive network comprised of a plurality of resistors; a plurality of switches, each switch coupled to one of the resistors and adapted to selectively switch the resistor in and out of the resistive network in response to the control signal; and a transistor adapted to apply a voltage across the resistive network to generate a current.

Digitally trimmed DAC cell

A DAC () including an operational amplifier () having an input terminal; a plurality of current paths coupled to the input terminal; a plurality of current sources (I/2 -I/2); and an arrangement () for switchably coupling current from at least two of the cells to a respective one of the paths in response to an input signal. In a specific embodiment, the inventive DAC () further includes a first resistive element (RR) disposed in each of the current paths, a second resistive element (R-R) disposed between the current paths, and a feedback resistor (R) disposed between an output terminal of the amplifier and the input terminal thereof. In the illustrative embodiment, the coupling arrangement includes a plurality of switches (SW-SW); each of the switches is adapted to switch half of the current from a first source and half of the current from a second source into a respective one of the paths. The invention is adapted to lower the distortion of digital to analog converters by improving differential nonlinearities and integral nonlinearities, caused primarily by current source gradient errors, without the need for trimming.

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Gardena, CA, United States of America

Christopher B Langit