Radio frequency signal power amplification circuit

Patent metadata

Field	Value
Publication number	US-9496827-B2
Application number	US-201514956826-A
Country	US
Kind code	B2
Filing date	Dec 2, 2015
Priority date	Apr 14, 2015
Publication date	Nov 15, 2016
Grant date	Nov 15, 2016

Abstract

An RF amplifier includes a branch with an inductor series-connected with a capacitor between first and second power supply nodes, a junction point between the inductor and capacitor forming an output node. A further branch includes a MOS transistor series-connected with a switch between the output node and the second power supply node. The switch has a control node coupled to receive a first input signal. The MOS transistor has a gate coupled to receive a second input signal. A control circuit applies the power supply voltage as the second input signal when a frequency/phase-modulated signal is applied as the first input signal. The control circuit further applies a variable signal as the second input signal when a radio frequency signal of constant frequency, phase, and amplitude is applied as the first input signal, and in this mode the MOS transistor is constrained to operate as a current source.

First claim

The invention claimed is:

1. A radio frequency signal power amplifier, comprising:
a first branch comprising an inductor series-connected with a first capacitor between a first node and a second node of application of a direct current (DC) power supply voltage, wherein a junction point of the inductor and the first capacitor forms an output node of the amplifier that is configured to be coupled to a load;
a second branch comprising a first MOS transistor series-connected with a first switch between the output node the second node, the first switch having a control node coupled to a first input node configured to receive a first input signal, the first MOS transistor having a gate coupled to a second input node configured to receive a second input signal; and
a circuit configured to generate a binary signal indicative of a sign of a difference between a drain-source voltage of the first transistor and a gate-source voltage minus a threshold voltage of the first transistor.

2. The amplifier of claim 1 , wherein the first MOS transistor is configured to operate as a controllable current source in response to the second input signal at the second input node.

3. The amplifier of claim 1 , wherein the first switch is a second MOS transistor configured to operate as a switching element in response to the first input signal at the first input node applied to a gate of said second MOS transistor.

4. The amplifier of claim 3 , wherein a gate oxide of the first MOS transistor is thicker than a gate oxide of the second MOS transistor.

5. The amplifier of claim 1 , wherein said circuit comprises:
a second capacitor and a second switch configured to sample a voltage representative of a voltage at the output node when the first switch is in the on state; and
a second MOS transistor, of a same type as the first MOS transistor, that is diode-mounted and biased to a conduction threshold, a drain of the second MOS transistor being coupled to a gate of the first MOS transistor.

6. The amplifier of claim 5 , wherein:
the second capacitor has a first electrode coupled to the second power supply node and a second electrode coupled to the output node by the second switch; and
a source of the second MOS transistor is coupled to the second power supply node by a current source, and
further comprising a comparator having a first input coupled to the second electrode of the second capacitor and a second input coupled to the source of the second MOS transistor.

7. The amplifier of claim 6 , wherein said binary signal is an output signal of said comparator.

8. The amplifier of claim 5 , wherein:
the second capacitor has a first electrode coupled to the second power supply node and a second electrode coupled to a midpoint of a first voltage dividing bridge circuit that couples the output node to the second power supply node; and
a source of the second MOS transistor is coupled to the second power supply node by a voltage dividing bridge circuit, and
further comprising a comparator having a first input coupled to the second electrode of the second capacitor and a second input coupled to the midpoint.

9. The amplifier of claim 8 , wherein said binary signal is an output signal of said comparator.

10. The amplifier of claim 4 , wherein the second switch has a control node coupled to the control node of the first switch.

11. The amplifier of claim 1 , further comprising:
a digital-to-analog converter circuit configured to convert a digital signal to an analog current supplied to the gate of the second MOS transistor;
wherein the digital signal has a value set responsive to said binary signal so as to constrain said second MOS transistor to operate as a current source.

12. A radio frequency signal transmission device, comprising:
an amplifier, said amplifier comprising:
a first branch comprising an inductor series-connected with a first capacitor between a first node and a second node of application of a direct current (DC) power supply voltage, wherein a junction point of the inductor and the first capacitor forms an output node of the amplifier that is configured to be coupled to a load;
a second branch comprising a first MOS transistor series-connected with a first switch between the output node the second node, the first switch having a control node coupled to a first input node configured to receive a first input signal, the first MOS transistor having a gate coupled to a second input node configured to receive a second input signal; and
a circuit configured to generate a binary signal indicative of a sign of a difference between a drain-source voltage of the first transistor and a gate-source voltage minus a threshold voltage of the first transistor;

a control circuit configured to alternately control the amplifier in:
a first operating mode where the gate of the first MOS transistor is coupled to the first power supply node and where a frequency-modulated radio frequency signal or phase-modulated radio frequency signal is applied to the first input node; and
a second operating mode where a radio frequency signal of constant frequency, phase, and amplitude is applied to the first input node and a variable signal for controlling current delivered by the first MOS transistor is applied to the second input node.

13. The radio frequency signal transmission device of claim 12 , wherein said circuit comprises:
a second capacitor and a second switch configured to sample a voltage representative of a voltage at the output node when the first switch is in the on state; and
a second MOS transistor, of a same type as the first MOS transistor, that is diode-mounted and biased to a conduction threshold, a drain of the second MOS transistor being coupled to a gate of the first MOS transistor.

14. The radio frequency signal transmission device of claim 13 , wherein:
the second capacitor has a first electrode coupled to the second power supply node and a second electrode coupled to the output node by the second switch; and
a source of the second MOS transistor is coupled to the second power supply node by a current source, and
further comprising a comparator having a first input coupled to the second electrode of the second capacitor and a second input coupled to the source of the second MOS transistor.

15. The radio frequency signal transmission device of claim 14 , wherein said binary signal is an output signal of said comparator.

16. The radio frequency signal transmission device of claim 13 , wherein:
the second capacitor has a first electrode coupled to the second power supply node and a second electrode coupled to a midpoint of a first voltage dividing bridge circuit that couples the output node to the second power supply node; and
a source of the second MOS transistor is coupled to the second power supply node by a voltage dividing bridge circuit, and
further comprising a comparator having a first input coupled to the second electrode of the second capacitor and a second input coupled to the midpoint.

17. The radio frequency signal transmission device of claim 16 , wherein said binary signal is an output signal of said comparator.

18. A radio frequency signal power amplifier, comprising:
an inductor coupled between a first power supply node and an output node;
a first capacitor coupled between the output node and a second power supply node;
a first MOS transistor coupled between a first intermediate node and the second power supply node;
where the first MOS transistor has a gate configured to receive a first input signal
a second MOS transistor coupl

Assignees

• Stmicroelectronics (Grenoble 2) Sas

Inventors

• Ayraud Michel

Classifications

• H03F1/0205 Primary

  in transistor amplifiers · CPC title

• H03F3/2171

  with field-effect devices (H03F3/2173 - H03F3/2178 take precedence) · CPC title

• H03F3/193

  with field-effect devices (H03F3/195 takes precedence) · CPC title

• H03F3/211

  using a combination of several amplifiers (H03F3/60 takes precedence) · CPC title

• H03F2203/21103

  An impedance adaptation circuit being added at the input of a power amplifier stage · CPC title