# US 8,786,373 B2 · Adjustable bypass circuit for a supply voltage for an amplifier > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,786,373 B2 - Document ID: US8786373B2 - Status: Granted - Kind: B2 - Application number: 13/401,255 - Filed: 2012-02-21 - Published: 2013-08-22 - Granted: 2014-07-22 - Earliest claimed: 2012-02-21 - Applicants: Calogero D. Presti; Jose Cabanillas - Inventors: Calogero D. Presti; Jose Cabanillas - Web page: https://patentgrep.com/patent/US8786373B2 ## CPC - H03F 1/0211: {with control of the supply voltage or current} - H03F 3/24: of transmitter output stages - H03F: AMPLIFIERS ## Abstract Techniques for bypassing a supply voltage for an amplifier are disclosed. In an exemplary design, an apparatus includes an amplifier and an adjustable bypass circuit. The amplifier (e.g., a power amplifier) receives a supply voltage from a supply source. The adjustable bypass circuit is coupled to the supply source and provides bypassing for the supply voltage. The adjustable bypass circuit includes an adjustable capacitor or a fixed capacitor coupled to an adjustable resistor. The supply source may be (i) a power supply source providing a fixed supply voltage for the amplifier or (ii) an envelope tracker providing a variable supply voltage for the amplifier. ## Claims ### Claim 1 An apparatus comprising: an amplifier configured to receive a supply voltage from a supply source; and an adjustable bypass circuit coupled to the supply source and configured to bypass the supply voltage, the adjustable bypass circuit comprising at least one of an adjustable capacitor or a fixed capacitor coupled in series to an adjustable resistor. ### Claim 2 (depends on 1) The apparatus of claim 1, the adjustable bypass circuit comprising the adjustable capacitor coupled between the supply source and circuit ground. ### Claim 3 (depends on 2) The apparatus of claim 2, the adjustable capacitor comprising a plurality of switchable capacitors, each switchable capacitor being selected or unselected based on a respective control signal for the switchable capacitor. ### Claim 4 (depends on 1) The apparatus of claim 1, the adjustable bypass circuit comprising the fixed capacitor and the adjustable resistor coupled in series and between the supply source and circuit ground. ### Claim 5 (depends on 4) The apparatus of claim 4, the adjustable resistor comprising a plurality of switchable resistors, each switchable resistor being selected or unselected based on a respective control signal for the switchable resistor. ### Claim 6 (depends on 4) The apparatus of claim 4, the adjustable resistor comprising a plurality of transistors, each transistor being selected or unselected based on a respective control signal for the transistor, each transistor providing an ON resistance when selected. ### Claim 7 (depends on 6) The apparatus of claim 6, the plurality of transistors having different sizes and providing different ON resistances when selected. ### Claim 8 (depends on 1) The apparatus of claim 1, the adjustable bypass circuit comprising an adjustable resistor coupled to the adjustable capacitor. ### Claim 9 (depends on 8) The apparatus of claim 8, the adjustable capacitor and the adjustable resistor are coupled in series and between the supply source and circuit ground. ### Claim 10 (depends on 9) The apparatus of claim 9, the adjustable capacitor comprising a plurality of switchable capacitors, each switchable capacitor being selected or unselected based on a respective first control signal for the switchable capacitor, and the adjustable resistor comprising a plurality of switchable resistors, each switchable resistor being selected or unselected based on a respective second control signal for the switchable resistor. ### Claim 11 (depends on 1) The apparatus of claim 1, the supply source comprising an envelope tracker configured to provide a variable supply voltage for the amplifier. ### Claim 12 An apparatus comprising: a plurality of amplifiers coupled to a common supply connection and configured to receive a supply voltage provided by a supply source to the common supply connection; and a plurality of switchable bypass capacitors coupled to the common supply connection and associated with the plurality of amplifiers, each of the plurality of switchable bypass capacitors being connected or disconnected from the common supply connection based on an operational state of an associated amplifier of the plurality of amplifiers. ### Claim 13 (depends on 12) The apparatus of claim 12, the supply source comprising an envelope tracker configured to provide a variable supply voltage to the common supply connection. ### Claim 14 (depends on 12) The apparatus of claim 12, wherein each of the plurality of switchable bypass capacitors is associated with one of the plurality of amplifiers, and wherein each switchable bypass capacitor is connected to the common supply connection when the associated amplifier is enabled and is disconnected from the common supply connection when the associated amplifier is disabled. ### Claim 15 (depends on 12) The apparatus of claim 12, further comprising: a fixed bypass capacitor coupled to the common supply connection. ### Claim 16 A method comprising: amplifying an input signal with an amplifier to obtain an amplified signal; and bypassing a supply voltage for the amplifier with an adjustable bypass circuit comprising at least one of an adjustable capacitor or a fixed capacitor coupled in series to an adjustable resistor. ### Claim 17 (depends on 16) The method of claim 16, further comprising: generating a variable supply voltage with an envelope tracker as the supply source; and providing the variable supply voltage as the supply voltage for the amplifier. ### Claim 18 An apparatus comprising: means for amplifying an input signal to obtain an amplified signal; and means for bypassing a supply voltage for the means for amplifying, the means for bypassing comprising at least one of an adjustable capacitor or a fixed capacitor coupled in series to an adjustable resistor. ### Claim 19 (depends on 18) The apparatus of claim 18, further comprising: means for generating a variable supply voltage as the supply source; and means for providing the variable supply voltage as the supply voltage for the amplifier.