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Method for using feedback to reduce the area and power of continuous-time filters

IP.com Disclosure Number: IPCOM000109306D
Publication Date: 2005-Mar-23
Document File: 3 page(s) / 20K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for using feedback to reduce the area and power of continuous-time filters. Benefits include improved functionality, improved power performance, and improved cost effectiveness.

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Method for using feedback to reduce the area and power of continuous-time filters

Disclosed is a method for using feedback to reduce the area and power of continuous-time filters. Benefits include improved functionality, improved power performance, and improved cost effectiveness.

Background

              A continuous-time filter is a signal processing block that sends data over twisted-pair copper cable with a transformer. Conventionally, the feedback resistors and capacitors are connected between the amplifier input and output (Vop and Vin).

              For any operational amplifier, capacitance loading of the output limits performance in terms of maximum achievable bandwidth. If the capacitance is unavoidably large, power consumption and the area inside the amplifier must be increased to drive the load to obtain the required bandwidth. However, to achieve a particular pole or zero location, which sets the required frequency response, a specific resistance-capacitance product (R*C) must be achieved.

General description

                            The disclosed method uses feedback to reduce the area and power of continuous-time filters. An operational amplifier is connected in negative feedback with capacitors and resistors so that its frequency response exhibits a band-pass characteristic. For example, the high-frequency noise due to crosstalk is attenuated.

      The key elements of the method include:

•             Linear metal-insulator-metal (MIM) capacitors

•             Poly-silicon resistors

•             Operational amplifier

Advantages

              The disclosed method provides advantages, including:

•             Improved functionality due to using feedback resistors and capacitors to optimize the area and power consumption of continuous-time filters

•             Improved power performance due to using a resistor string to sense the amplifier’s common-mode output and provi...