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US 6,388,589 B1Granted
Programmable video interface
AssigneeTRW Inc.
InventorGeorge T. Arai
Life of this patent
Estimating the term…
Abstract
A programmable video interface (20) eliminates the need for select-in-test parts during manufacture. The video interface (20) includes a scaling module (40) and a programming module (60). The scaling module (40) converts an analog input signal into a digital output signal based on a plurality of analog programming signals. The programming module (60) generates the plurality of analog programming signals, where the analog programming signals maintain operation of the scaling module at a predetermined transfer characteristic and an associated tolerance. The programming module generates the plurality of analog programming signals based on digital programming data. The use of D/A converters (62, 64) in the programming module (60) allows the elimination of resistor divider networks and associated tolerance problems.
Claims18
A programmable video interface comprising:
- a scaling module for converting an analog input signal into a digital output signal based on a plurality of analog programming signals;
- and
- a programming module for generating the plurality of analog programming signals, the analog programming signals maintaining operation of the scaling module at a predetermined transfer characteristic and an associated tolerance;
- said programming module generating the plurality of analog programming signals based on digital programming data;
- wherein the programming module includes
- an offset digital to analog converter for generating an analog offset signal based on digital offset data;
- and
- a gain digital to analog converter for generating an analog gain signal based on digital gain data;
- and wherein said plurality of analog programming signals includes the analog offset signal and the analog gain signal.
6 more elements
A programmable video interface comprising:
- a scaling module for converting an analog input signal into a digital output signal based on a plurality of analog programming signals;
- and
- a programming module for generating the plurality of analog programming signals, the analog programming signals maintaining operation of the scaling module at a predetermined transfer characteristic and an associated tolerance;
- said programming module generating the plurality of analog programming signals based on digital programming data;
- wherein the programming module includes:
- an offset digital to analog converter for generating an analog offset signal based on digital offset data;
- a gain digital to analog converter for generating an analog gain signal based on digital gain data;
- and
- said plurality of analog programming signals including the analog offset signal and the analog gain signal;
- wherein the scaling module includes
- a log amplifier for converting the analog input signal into a log output based on a logarithmic scale;
- a differential amplifier for comparing the log output to one of the analog programming signals, the differential amplifier level shifting its output based on the comparison;
- and
- an analog to digital converter for converting the level shifted signal into the digital output signal based on one of the analog programming signals, the conversion signal mapping a nominal output signal range of the log amplifier to an input range of the analog to digital converter.
11 more elements
A programming module for generating a plurality of analog programming signals, the programming module comprising:
- an offset digital to analog converter for generating an analog offset signal based on digital offset data;
- and
- a gain digital to analog converter for generating an analog gain signal based on digital gain data;
- said plurality of analog programming signals including the analog offset signal and the analog gain signal, the analog offset signal and the analog gain signal maintaining operation of a programmable video interface scaling module at a predetermined transfer characteristic and an associated tolerance.
1 more element
A method for programming a video interface programming module, the method comprising the steps of:
- determining digital offset data for the programming module, the digital offset data corresponding to a predetermined transfer characteristic for the video interface, the programming module transmitting an analog offset signal to a scaling module based on the digital offset data;
- determining digital gain data for the programming module, the digital gain data corresponding to the predetermined transfer characteristic, the programming module transmitting an analog gain signal to the scaling module based on the digital gain data, the scaling module converting an analog input signal into a digital output signal based on the predetermined transfer characteristic;
- and
- storing the digital offset data and the digital gain data to a programmable memory device;
- wherein the step of converting the analog input signal into the digital output signal includes the steps of converting the analog input signal into a log output with a log amplifier based on a logarithmic scale, generating a conversion signal with a differential amplifier based on the log output and the analog offset signal, and converting the conversion signal into the digital output signal with an analog to digital converter, the method further including the steps of
- (a) setting the digital gain data to produce a full-scale output from the analog to digital converter;
- (b) setting the digital offset data to produce a mid-scale output from the differential amplifier;
- (c) injecting a known analog input signal into the log amplifier at a first predetermined level and a second predetermined level, the first predetermined level and the second predetermined level defining a predetermined delta;
- (d) dividing the predetermined delta by a difference in the digital output signal;
- and
- (e) adjusting the digital gain data such that the predetermined delta and the difference in the digital output signal approximate the predetermined transfer characteristic.
8 more elements
A method for programming a video interface programming module, the method comprising the steps of:
- determining digital offset data for the programming module, the digital offset data corresponding to a predetermined transfer characteristic for the video interface, the programming module transmitting an analog offset signal to a scaling module based on the digital offset data;
- determining digital gain data for the programming module, the digital gain data corresponding to the predetermined transfer characteristic, the programming module transmitting an analog gain signal to the scaling module based on the digital gain data, the scaling module converting an analog input signal into a digital output signal based on the predetermined transfer characteristic;
- storing the digital offset data and the digital gain data to a programmable memory device;
- further including the steps of:
- injecting a known analog input signal input into the scaling module;
- and
- adjusting the digital offset data such that the digital output signal equals a predetermined digital output value.
4 more elements
A method for programming a video interface programming module, the method comprising the steps of:
- determining digital offset data for the programming module, the digital offset data corresponding to a predetermined transfer characteristic for the video interface, the programming module transmitting an analog offset signal to a scaling module based on the digital offset data;
- determining digital gain data for the programming module, the digital gain data corresponding to the predetermined transfer characteristic, the programming module transmitting an analog gain signal to the scaling module based on the digital gain data, the scaling module converting an analog input signal into a digital output signal based on the predetermined transfer characteristic;
- storing the digital offset data and the digital gain data to a programmable memory device;
- and
- testing the scaling module for stuck bits.
2 more elements
Dependencies are inferred from the claim text.