# US 2010/0164656 A1 · Integrated digitally controlled linear-in-decibels attenuator > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2010/0164656 A1 - Document ID: US20100164656A1 - Status: Published application - Kind: A1 - Application number: 12/719,432 - Filed: 2010-03-08 - Published: 2010-07-01 - Earliest claimed: 2005-06-14 - Assignees: National Semiconductor Corporation - Inventors: Hon Kin Chiu - Web page: https://patentgrep.com/patent/US20100164656A1 ## CPC - H03H 7/24: Frequency- independent attenuators - H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P) ## Abstract An integrated digitally controlled linear-in-decibels attenuator circuit in which one or more sets of selection switches establish a desired attenuation by selectively connecting the input signal electrode to one or more corresponding resistive ladder networks connected in series, thereby providing a substantially more constant signal attenuation value over a wider frequency bandwidth. With a single resistive ladder network, attenuation control is achieved using a thermometer switching code. With multiple resistive ladder networks, coarse and fine attenuation control can be achieved using thermometer and bubble switching codes, respectively. ## Claims ### Claim at position 1 -20. (canceled) ### Claim 21 An apparatus including an integrated digitally controlled linear-in-decibels attenuator circuit, comprising: first switched resistance circuitry responsive to a first plurality of digital control signals by attenuating an input signal to provide a first attenuated signal having a magnitude substantially in accordance with one of a first plurality of attenuation values mutually separated by a first attenuation step substantially in accordance with a thermometer code; and second switched resistance circuitry coupled to said first switched resistance circuitry and responsive to a second plurality of digital control signals by attenuating said first attenuated signal to provide a second attenuated signal having a magnitude substantially in accordance with one of a second plurality of attenuation values mutually separated by a second attenuation step substantially in accordance with a bubble code, wherein said second attenuation step is smaller than said first attenuation step; wherein a ratio of said second attenuated signal and said input signal is one of a plurality of ratio values mutually separated by linear-in-decibels steps. ### Claim 22 (depends on 21) The apparatus of claim 21, wherein: said first switched resistance circuitry is responsive to said first plurality of digital control signals during a first time interval such that said first attenuated signal magnitude transitions through a first plurality of signal magnitudes; and said second switched resistance circuitry is responsive to said second plurality of digital control signals during a second time interval such that said second attenuated signal magnitude transitions through a second plurality of signal magnitudes. ### Claim 23 (depends on 22) The apparatus of claim 22, wherein: said first plurality of signal magnitudes are mutually related by said first attenuation step; and said second plurality of signal magnitudes are mutually related by said second attenuation step. ### Claim 24 (depends on 21) The apparatus of claim 21, wherein: said first plurality of attenuation values comprises M attenuation values; said second plurality of attenuation values comprises N attenuation values; and said plurality of ratio values comprises M*N attenuation values. ### Claim 25 (depends on 21) The apparatus of claim 21, wherein: said first switched resistance circuitry includes M stages of switched resistances; said second switched resistance circuitry includes N stages of switched resistances; and said first and second switched resistance circuitries together provide M*N attenuation values. ### Claim 26 (depends on 21) The apparatus of claim 21, wherein: said first switched resistance circuitry includes a first plurality of series resistances each of which having a resistance Rs1 related to a reference resistance Rr and a first scalar A substantially in accordance with Rs1=Rr/A−Rr, and a first plurality of shunt resistances each of which having a resistance Rp1 related to said reference resistance Rr and said first scalar A substantially in accordance with Rp1=Rr/(1=A); and said second switched resistance circuitry includes a second plurality of series resistances each of which having a resistance Rs2 substantially equal to said reference resistance Rr, and a second plurality of shunt resistances each of which having a resistance Rp2 related to said reference resistance Rr and a second scalar K substantially in accordance with Rp2=(ReK/(1−K))*((Rr*K/(1−K))+Rr)/Rr. ### Claim 27 A method for attenuating a signal in a linear-in-decibels manner in accordance with a plurality of digital control signals, comprising: attenuating an input signal in accordance with a first plurality of digital control signals to provide a first attenuated signal having a magnitude substantially in accordance with one of a first plurality of attenuation values mutually separated by a first attenuation step substantially in accordance with a thermometer code; and attenuating said first attenuated signal in accordance with a second plurality of digital control signals to provide a second attenuated signal having a magnitude substantially in accordance with one of a second plurality of attenuation values mutually separated by a second attenuation step substantially in accordance with a bubble code, wherein said second attenuation step is smaller than said first attenuation step; wherein a ratio of said second attenuated signal and said input signal is one of a plurality of ratio values mutually separated by linear-in-decibels steps. ### Claim 28 (depends on 27) The method of claim 27, wherein: said attenuating an input signal comprises attenuating said input signal in accordance with said first plurality of digital control signals during a first time interval such that said first attenuated signal magnitude transitions through a first plurality of signal magnitudes; and said attenuating said first attenuated signal comprises attenuating said first attenuated signal in accordance with said second plurality of digital control signals during a second time interval such that said second attenuated signal magnitude transitions through a second plurality of signal magnitudes. ### Claim 29 (depends on 28) The method of claim 28, wherein: said first plurality of signal magnitudes are mutually related by said first attenuation step; and said second plurality of signal magnitudes are mutually related by said second attenuation step. ### Claim 30 (depends on 27) The method of claim 27, wherein: said first plurality of attenuation values comprises M attenuation values; said second plurality of attenuation values comprises N attenuation values; and said plurality of ratio values comprises M*N attenuation values. ### Claim 31 (depends on 27) The method of claim 27, wherein: said attenuating an input signal comprises switching said input signal among M stages of switched resistances; said attenuating said first attenuated signal comprises switching said first attenuated signal among N stages of switched resistances; and said M and N stages of switched resistances together provide M*N attenuation values. ### Claim 32 (depends on 27) The method of claim 27, wherein: said attenuating an input signal comprises switching said input signal among M stages of switched resistances including a first plurality of series resistances each of which having a resistance Rs1 related to a reference resistance Rr and a first scalar A substantially in accordance with Rs1=Rr/A−Rr, and a first plurality of shunt resistances each of which having a resistance Rp1 related to said reference resistance Rr and said first scalar A substantially in accordance with Rp1=Rr/(1−A); and said attenuating said first attenuated signal comprises switching said first attenuated signal among N stages of switched resistances including a second plurality of series resistances each of which having a resistance Rs2 substantially equal to said reference resistance Rr, and a second plurality of shunt resistances each of which having a resistance Rp2 related to said reference resistance Rr and a second scalar K substantially in accordance with Rp2=(Rr*K/(1−K))*((Rr*KJ(1−K))+Rr)/Rr.