RF amplifier

Patent metadata

Field	Value
Publication number	US-10284148-B2
Application number	US-201815865145-A
Country	US
Kind code	B2
Filing date	Jan 8, 2018
Priority date	Jan 9, 2017
Publication date	May 7, 2019
Grant date	May 7, 2019

Abstract

An RF amplifier is described including an input, an output, a parallel arrangement of a first branch and at least one further branch, each branch comprising a bipolar transistor in a degenerative emitter configuration having a base coupled to the input, a collector coupled to a common collector node, and an emitter degeneration impedance arranged between the emitter and a common rail. The common collector node is coupled to the output, the base of the first branch bipolar transistor is biased at a first bias voltage and the base of the at least one further branch bipolar transistor is biased at a bias voltage offset from the first bias voltage. In operation of the RF amplifier a IM3 distortion current output by the first branch bipolar transistor is in antiphase to a IM3 distortion current output by the at least one further branch bipolar transistor.

First claim

The invention claimed is:

1. An RF amplifier comprising:
an input,
an output,
a parallel arrangement of a first branch and at least one further branch, each branch comprising a bipolar transistor in a degenerative emitter configuration having a base coupled to the input, a collector coupled to a common collector node, and an emitter degeneration impedance arranged between the emitter and a common rail;
wherein the common collector node is coupled to the output, the base of the first branch bipolar transistor is biased at a first bias voltage and the base of the at least one further branch bipolar transistor is biased at a bias voltage offset from the first bias voltage, and wherein in operation a IM3 distortion current output by the first branch bipolar transistor is in antiphase to a IM3 distortion current output by the at least one further branch bipolar transistor.

2. The RF amplifier of claim 1 further comprising a resonant circuit coupled between the input and the common rail.

3. The RF amplifier of claim 2 wherein the resonant circuit comprises a series arrangement of an inductance and a capacitance.

4. The RF amplifier of claim 3 wherein at least one of the inductance and capacitance has a variable value.

5. The RF amplifier of claim 1 wherein the common rail is a ground.

6. The RF amplifier of claim 1 wherein the value of the respective emitter degeneration impedance in each branch is within 10 percent of the ratio of the transit time and the base emitter junction capacitance of the respective bipolar transistor, and wherein the phase of the IM3 distortion current is independent of the bias voltage.

7. The RF amplifier of claim 1 wherein each branch comprises a capacitance arranged between the base of the bipolar transistor and the emitter of the bipolar transistor and wherein the phase of the IM3 distortion current is independent of the bias voltage.

8. The RF amplifier of claim 1 wherein the emitter degeneration impedance in each branch comprises a resistance in parallel with a capacitance and wherein the phase of the IM3 distortion current is independent of the bias voltage.

9. The RF amplifier of claim 1 wherein each of the first branch and the at least one further branch further comprises an AC coupling capacitor arranged between the input and the respective base of the first branch and the at least one further branch bipolar transistors.

10. The RF amplifier of claim 1 further comprising an output stage comprising a RF choke arranged between a supply rail and the common collector node, and a capacitance arranged between the common collector node and the output.

11. The RF amplifier of claim 1 wherein each branch comprises a respective bias circuit coupled to the base of the respective bipolar transistor and wherein the bias circuit comprises a gyrator.

12. The RF amplifier of claim 11 wherein the gyrator comprises a NPN bipolar transistor, a first resistance arranged between a supply voltage rail and the collector, a second resistance arranged between the collector and the base and a capacitance arranged between the base and a ground rail.

13. The RF amplifier of claim 1 further comprising a common-base stage comprising a bipolar transistor having an emitter coupled to the common collector node, a collector coupled to the amplifier output, and a base connected to a common-base bias circuit.

14. The RF amplifier of claim 1 further comprising:
a first common-base stage comprising a first common-base stage bipolar transistor having an emitter coupled to the first branch, a collector coupled to the common collector node, and a base connected to a common-base bias circuit, and
at least one further common-base stage comprising at least one further common-base stage bipolar transistor having an emitter coupled to the at least one further branch, a collector coupled to the common collector node, and a base connected to the common-base bias circuit.

15. The RF amplifier of claim 1 configured as a class A or class AB amplifier.

Assignees

• Nxp Bv

Inventors

• D'Avino Marco
• Van Der Heijden Mark Pieter
• Groenewegen Michel Wilhelmus Arnoldus
• De Vreede Leonardus Cornelis Nicolaas

Classifications

• H03F1/3205 Primary

  in field-effect transistor amplifiers · CPC title

• H03F2200/75

  the amplifier stage being a common source configuration MOSFET · CPC title

• H03F2200/225

  the input circuit of an amplifying stage comprising an LC-network · CPC title

• H03F2200/498

  A resistor being added in the source circuit of a transistor amplifier stage as degenerating element · CPC title

• H03F3/195

  in integrated circuits · CPC title