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Systems and methods for auto gain control in bi-CMOS digital to analog converters

a digital to analog converter and gain control technology, applied in the field of digital to analog converters, can solve problems such as current flow into the device base, achieve the effect of ensuring the accuracy of the output power of a dac, reducing the variation in these factors, and gaining the accuracy of the da

Active Publication Date: 2006-04-27
AVAGO TECH INT SALES PTE LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a system to ensure the accuracy of output power in a digital-to-analog converter (DAC) by reducing variations in factors that affect the gain accuracy of the DAC. The system includes a bandgap portion, replica circuit, and a DAC. The bandgap portion provides a constant voltage, while the replica circuit provides an appropriate current to drive the DAC. This results in a more stable and accurate output power from the DAC.

Problems solved by technology

Third, when bipolar devices are used there is some current flow into the base of the devices due to finite beta (β) values.

Method used

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  • Systems and methods for auto gain control in bi-CMOS digital to analog converters
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  • Systems and methods for auto gain control in bi-CMOS digital to analog converters

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Embodiment Construction

[0020] While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those skilled in the art with access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the invention would be of utility.

[0021]FIG. 1 provides a diagram of DAC 100. DAC 100 has resistor loads 102 and 104 sourcing or sinking current out from several differential pairs, as illustrated by differential pairs 110, 120, and 130 with constant current source. Thus, the voltage drop across the resistor load is proportional to the digital codes, and output voltage swing is proportional to the product of the effective output resistance and the biasing current in the differential pair. The design and operation of DACs will be known by individuals skilled in the relevant arts.

[0022] As discussed...

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Abstract

The accuracy of output power in a digital-to-analog converter (DAC) is critical in certain applications. When bi-CMOS technology is used to implement a DAC, a number of factors affect the gain accuracy of the DAC. The present invention provides a circuit architecture to reduce the variation in these factors to ensure the accuracy of the output power of a DAC. The architecture comprises a bandgap portion, replica circuit and a DAC. The bandgap portion of the architecture provides a constant voltage, while the replica circuit provide a correct current to drive the DAC.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of priority to U.S. Provisional Patent Application, Application No. 60 / 620,971, filed Oct. 22, 2004, which is incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The invention relates to digital-to-analog converters (DAC), and more particularly to automatic gain control in DACs. [0004] 2. Background Art [0005] A digital-to-analog converter (DAC) is an electronic circuit that receives an n-bit digital word from an interface circuit and generates an analog output that is proportional to the received digital word. Digital codes are typically converted to analog voltages by assigning a voltage weight to each bit in the digital code and then summing the voltage weights of the entire code. [0006] DACs can be designed for a wide range of applications, including general data acquisition applications and special applications, such as, but not lim...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H03M1/66
CPCH03M1/0845H03M1/742
Inventor CHEN, CHUN-YING
Owner AVAGO TECH INT SALES PTE LTD