# US 10,122,325 B2 · Distributed amplifier with improved stabilization > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,122,325 B2 - Document ID: US10122325B2 - Status: Granted - Kind: B2 - Application number: 15/240,580 - Filed: 2016-08-18 - Published: 2017-02-09 - Granted: 2018-11-06 - Earliest claimed: 2011-03-09 - Assignees: Hittite Microwave Corporation - Applicants: Hittite Microwave LLC - Inventors: Keith Benson - Web page: https://patentgrep.com/patent/US10122325B2 ## CPC - H03F 1/18: by use of distributed coupling {, i.e. distributed amplifiers (distributed amplifiers using coupling networks with distributed constants H03F3/605)} - H03F 1/086: {with FET's} - H03F 1/223: {with MOSFET's} - H03F 1/42: Modifications of amplifiers to extend the bandwidth - H03F 3/19: with semiconductor devices only - H03F 3/193: with field-effect devices (H03F3/195 takes precedence) - H03F 3/607: {using FET's} - H03F 2200/108: A coil being added in the drain circuit of a FET amplifier stage, e.g. for noise reducing purposes - H03F 2200/144: the feedback circuit of the amplifier stage comprising a passive resistor and passive capacitor - H03F 2200/153: Feedback used to stabilise the amplifier - H03F 2200/267: A capacitor based passive circuit, e.g. filter, being used in an amplifying circuit - H03F 2200/423: Amplifier output adaptation especially for transmission line coupling purposes, e.g. impedance adaptation - H03F 2200/61: the cascode amplifier has more than one common gate stage - H03F: AMPLIFIERS ## Abstract A distributed amplifier with improved stabilization includes an input transmission circuit, an output transmission circuit, at least one cascode amplifier coupled between said input and output transmission circuits. Each cascode amplifier includes a common-gate configured transistor coupled to the output transmission circuit, and a common-source configured transistor coupled between the input transmission circuit and the common-gate configured transistor. The distributed amplifier also includes a non-parasitic resistance and capacitance coupled in series between a drain and a gate of at least one of the common-gate configured transistors for increasing the amplifier stability. ## Claims ### Claim 1 A distributed amplifier comprising: an input transmission line; an output transmission line; and a plurality of cascode amplifiers each coupled between the input transmission line and the output transmission line, wherein a first cascode amplifier of the plurality of cascode amplifiers comprises: three or more bipolar transistors arranged in a stack, including a first bipolar transistor, a second bipolar transistor, and a third bipolar transistor, wherein the first bipolar transistor includes a base coupled to the input transmission line, wherein the second bipolar transistor is positioned between the first bipolar transistor and the third bipolar transistor in the stack, and wherein the third bipolar transistor includes a collector coupled to the output transmission line, a first feedback resistor and a first feedback capacitor electrically connected in series between a collector of the second bipolar transistor and a base of the second bipolar transistor, a second feedback resistor and a second feedback capacitor electrically connected in series between the collector of the third bipolar transistor and a base of the third bipolar transistor, a first biasing resistor including a first terminal configured to receive a first DC voltage and a second terminal electrically connected to the base of the second bipolar transistor, and a first shunt circuit electrically connected between the second terminal of the first biasing resistor and a ground node, the first shunt circuit including a first base resistor and a first base capacitor in series. ### Claim 2 (depends on 1) The distributed amplifier of claim 1, further comprising a base line termination coupled to the input transmission line and a collector line termination coupled to the output transmission line. ### Claim 3 A distributed amplifier comprising: an input transmission line; an output transmission line; and a plurality of cascode amplifiers each coupled between the input transmission line and the output transmission line, wherein a first cascode amplifier of the plurality of cascode amplifiers comprises: three or more bipolar transistors arranged in a stack, wherein the three or more bipolar transistors comprises a first bipolar transistor, a second bipolar transistor, and a third bipolar transistor, wherein the first bipolar transistor includes a base coupled to the input transmission line, wherein the second bipolar transistor is positioned between the first bipolar transistor and the third bipolar transistor in the stack, and wherein the third bipolar transistor includes a collector coupled to the output transmission line, a first stabilization circuit coupled between a base of the third bipolar transistor and the collector of the third bipolar transistor, wherein the first stabilization circuit comprises a first resistor and a first capacitor electrically connected in series, and wherein the first stabilization circuit is configured to direct a radio frequency (RF) feedback signal from the collector of the third bipolar transistor to the base of the third bipolar transistor, a second resistor and a second capacitor electrically connected in series between the base of the third bipolar transistor and a ground node, and a second stabilization circuit, coupled to a base of the second bipolar transistor, comprising a third resistor and a third capacitor electrically connected in series. ### Claim 4 (depends on 3) The distributed amplifier of claim 3, wherein the first resistor has a resistance value in the range of between 20 ohms to 10K ohms. ### Claim 5 (depends on 3) The distributed amplifier of claim 3, further comprising a base line termination coupled to the input transmission line and a collector line termination coupled to the output transmission line. ### Claim 6 (depends on 3) The distributed amplifier of claim 3, wherein the first stabilization circuit is configured to inhibit parametric oscillations. ### Claim 7 (depends on 1) The distributed amplifier of claim 1 further comprising a second biasing resistor including a first terminal configured to receive a second DC voltage and a second terminal electrically connected to the base of the third bipolar transistor, and a second shunt circuit electrically connected between the second terminal of the second biasing resistor and the ground node, the second shunt circuit including a second base resistor and a second base capacitor in series. ### Claim 8 (depends on 1) The distributed amplifier of claim 1 further comprising a voltage source configured to generate the first DC voltage. ### Claim 9 (depends on 3) The distributed amplifier of claim 3 further comprising a fourth resistor and a voltage source connected in series between the input transmission line and ground. ### Claim 10 (depends on 3) The distributed amplifier of claim 3 further comprising a fourth capacitor connected between the input transmission line and ground. ### Claim 11 (depends on 3) The distributed amplifier of claim 3 further comprising an inductor connected between a power supply voltage and the output transmission line. ### Claim 12 (depends on 3) The distributed amplifier of claim 3 wherein the plurality of cascode amplifiers include at least three cascode amplifiers. ### Claim 13 (depends on 1) The distributed amplifier of claim 1 further comprising an inductor connected between a power supply voltage and the output transmission line. ### Claim 14 (depends on 1) The distributed amplifier of claim 1 further comprising a second base resistor and a second base capacitor in series between the base of the third bipolar transistor and ground. ### Claim 15 (depends on 1) The distributed amplifier of claim 1 further comprising a second biasing resistor including a first terminal configured to receive a second DC voltage and a second terminal electrically connected to the base of the third bipolar transistor. ### Claim 16 (depends on 15) The distributed amplifier of claim 15 further comprising a voltage source configured to generate the second DC voltage. ### Claim 17 (depends on 1) The distributed amplifier of claim 1 further comprising a resistor and a voltage source connected in series between the input transmission line and ground. ### Claim 18 (depends on 1) The distributed amplifier of claim of claim 1 wherein the plurality of cascode amplifiers include at least three cascode amplifiers. ### Claim 19 (depends on 1) The distributed amplifier of claim 1 further comprising a capacitor connected between the input transmission line and ground. ### Claim 20 (depends on 1) The distributed amplifier of claim 1 further comprising a capacitor connected between the output transmission line and ground.