Raytheon Company

Hughes Aircraft Company

Telasic Communications, Inc.

Telasic Communication, Inc.

Roger N Kosaka

Lloyd Frederick Linder

Erick M Hirata

Christopher B Langit

Don C Devendorf

Edwin A Kelley

Benjamin Felder

Kelvin T Tran

Donald G McMullin

Hieu M Le

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.

Split cell bowtie digital to analog converter and method

A current steering circuit diverts bias current from a differential current summing amplifier's front end when the differential input exceeds a safe threshold level, thus preventing the amplifier's output stage from being overdriven. Diverting the front end's bias currents also turns off transistors within the amplifier's front end and thus protects the front end from damage which may otherwise result from excessive input signals.

Current feedback differential amplifier clamp

Multiple simultaneous uses of a multi-service digital receiver are made possible with a single practical analog-to-digital converter by translating the various service bands in frequency to form a single, generally continuous composite service band in which substantial frequency gaps between the different services are eliminated. Bandwidth requirements are further reduced by a bandfolding technique in which at least one service waveband is divided about an intermediate mixing frequency, the divided portions are overlapped so that they collectively occupy a sub-waveband with a smaller bandwidth than the original band, and the mixing frequency is chosen such that user-selected frequencies do not interfere with other active frequencies. Interference between non-selected active frequencies is permissible and simply ignored.

Multi-band digital receiving apparatus and method with bandwidth

Growing community of inventors

Torrance, CA, United States of America

Roger N Kosaka