Methods and apparatus for detecting the envelope of RF power signals

• US 7,257,384 B2
• Filed: 04/18/2003
• Issued: 08/14/2007
• Est. Priority Date: 06/03/2002
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Paragon Communications Limited
• Inventors: Veinblat, Alexander, Bar-David, Israel
• Primary Examiner(s): Nguyen, Duc M.
• Assistant Examiner(s): LEE, JUSTIN YE
• Application Number:
  US10/418,905
• Publication Number:
  US 20040018821A1
• Time in Patent Office: 1,579 Days
• Field of Search: 455130-144, 330/296
• US Class Current: 455/149
• CPC Class Codes: H03C 1/36 by means of semiconductor device having at least three electrodes H03C1/34, H03C1/50, H03C1/52, H03C1/62 take precedence
• CPC Class Codes: H03F 3/193 with field-effect devices H03F3/195 takes precedence

Abstract

Apparatus for detecting the envelope of an RF signal that comprises an RF transistor operating essentially at a non-linear operating point at the RF frequency range; a DC power supply for feeding the RF transistor; a dummy load for terminating the output of the RF transistor; and at lease one impedance, through which the DC power supply feeds the RF transistor, for obtaining an indication signal developed across the impedance. The indication signal represents the envelope, from the fluctuating current drawn by the RF transistor from the DC power supply during the time period when the RF signal is applied to the feeding input.

Claims

1. A method for detecting an envelope of an RF signal being input to an RF transistor wherein whenever the RF transistor is a FET having a grounded source or a bipolar transistor having a grounded emitter, wherein the output signal is obtained by performing the following steps:

a) providing said RF transistor operating essentially at a non-linear operating point at the RF frequency range, said RF transistor being fed by a DC power supply through an RF filter and terminated by a dummy load for RF components in an output signal of said RF transistor;

b) feeding said RF signal into the input of said RF transistor;

c) obtaining an output signal representing said envelope from the fluctuating output current drawn by said RF transistor from said DC power supply during a time period when said RF signal is applied to said input;

d) connecting a first contact of an RF filter to one of a drain of said FET or to a collector of said bipolar transistor;

e) connecting a more negative contact of the DC power supply to ground;

f) connecting a more positive contact of said DC power supply to a second contact of said RF filter through an impedance; and

g) coupling the voltage developed across said impedance by a coupling capacitor, thereby determining the polarity of the output signal to be opposite to the polarity of said DC power supply;

wherein the output signal is obtained by filtering out the RF components from the fluctuating current, thereby obtaining the mean detected current, being monotonically related to the envelope of the RF signal.

2. A method for detecting an envelope of an RF signal being input to an RF transistor wherein the RF transistor is a FET having a drain, or a bipolar transistor having an collector, being connected to the more positive contact of the DC power supply, wherein the output signal is obtained by performing the following steps:

a) providing said RF transistor op crating essentially at a non-linear operating point at the RF frequency range, said RF transistor being fed by a DC power supply through an RF filter and terminated by a dummy load for RF components in an output signal of said RF transistor;

b) feeding said RF signal into the input of said RF transistor;

c) obtaining an output signal representing said envelope from the fluctuating output current drawn by said RF transistor from said DC power supply during a time period when said RF signal is applied to said input;

d) connecting a more negative contact of the DC power supply to ground;

e) connecting one of a source of said FET or the emitter of said bipolar transistor to ground through an impedance;

f) biasing one of a gate of said FET, or the base of said bipolar transistor, through a biasing resistor connected in series with an RF filter, connected to said gate or to said base;

g) connecting a capacitor between a common contact of said RF filter and said biasing resistor, and said source or said emitter; and

h) coupling the voltage developed across said impedance by a coupling capacitor, thereby determining the polarity of the output signal to have polarity being similar to the polarity of said DC power supply;

wherein the output signal is obtained by filtering out the RF components from the fluctuating current,thereby obtaining the mean detected current, being monotonically related to the envelope of the RF signal.

3. A method according to claim 2, further comprising obtaining two output signals having opposite polarities by performing the following steps:

a) connecting a first contact of an RF filter to one of a drain of said FET or to a collector of said bipolar transistor;

b) connecting the more negative contact of the DC power supply to ground;

c) connecting the more positive contact of said DC power supply to the other contact of said RF filter through a first impedance;

d) connecting one of the source of said FET or the emitter of said bipolar transistor to ground through a second impedance;

e) biasing one of the gate of said FET or the base of said bipolar transistor through a biasing resistor connected in series with an RF filter, connected to one of gate or to said base;

f) connecting a capacitor between the common contact of said RF filter and said biasing resistor, and said source or said emitter;

g) coupling the voltage developed across said first impedance by a coupling capacitor, thereby determining the polarity of the output signal to be opposite to the polarity of said DC power supply; and

h) coupling the voltage developed across said second impedance by a coupling capacitor, thereby determining the polarity of the output signal to have polarity being similar to the polarity of said DC power supply.

4. Apparatus for detecting the envelope of an RF signal being input to an RF transistor, comprising:

a) an RF transistor operating essentially at a non-linear operating point at the RF frequency range;

b) a DC power supply for feeding said RF transistor;

c) a dummy load for terminating the output of said RF transistor; and

d) at least one impedance through which said DC power supply feeds said RF transistor, for obtaining an indication signal developed across said impedance, said indication signal representing said envelope, from the fluctuating current drawn by said RF transistor from said DC power supply during the time period when said RF si goal is applied to the feeding input;

e) an RF power transistor biased to operate essentially under Class B condition at the RF frequency range;

f) a DC power supply for feeding said RF transistor connected to ground by a first capacitor, and to an output port of said RF transistor through an RF filter for isolating RF frequency components from reaching said DC power supply;

g) an input matching circuitry for matching said RF transistor to the source of the RF signal, the amplitude of which is detected;

h) an output matching circuitry for matching said RF transistor to a dummy load, terminating said output port; and

i) an output contact, connected to a contact of said RF filter, at which an indication signal representing said amplitude, or variations in said amplitude, from the fluctuating current drawn by said RF transistor from said DC power supply during the time period when said RF signal is applied by said source, is developed.

5. Apparatus for detecting the envelope of an RF signal being input to an RF transistor wherein the RF transistor is a FET having a grounded source or a bipolar transistor having a grounded emitter, comprising:

a) an RF transistor operating essentially at a non-linear operating point at the RF frequency range;

b) a DC power supply for feeding said RF transistor;

c) a dummy load for terminating the output of said RF transistor; and

d) at least one impedance through which said DC power supply feeds said RF transistor, for obtaining an indication signal developed across said impedance, said indication signal representing said envelope, from the fluctuating current drawn by said RF transistor from said DC power supply during the time period when said RF signal is applied to the feeding input;

e) an RF filter, connected to one of a drain of said FET or to a collector of said bipolar transistor;

f) a DC power supply, having a negative contact being connected to ground and a positive contact being connected to the other contact of said RF filter through an impedance; and

g) a coupling capacitor, connected to said other contact, for coupling the voltage developed across said impedance, the polarity of which being opposite to the polarity of said DC power supply.

6. Apparatus for detecting the envelope of an RF signal being input to an RF transistor in which the RF transistor is a FET having a drains or a bipolar transistor having a collector, being connected to the more positive contact of the DC power supply through an RF filter, the more negative contact of which is connected to ground, comprising:

a) an RF transistor operating essentially at a non-linear operating point at the RF frequency range;

b) a DC power supply for feeding said RF transistor;

c) a dummy load for terminating the output of said RF transistor;

d) at least one impedance, through which said DC power supply feeds said RF transistor, for obtaining an indication signal developed across said impedance, said indication signal representing said envelope, from the fluctuating current drawn by said RF transistor from said DC power supply during the lime period when said RF signal is applied to the feeding input;

e) a first impedance, connected between one of a source of said FET, or an emitter of said bipolar transistor, and ground;

f) a biasing resistor, connected in series with an RF filter that is connected to one of the gate of said FET or to the base of said bipolar transistor, for biasing said gate or said base;

g) a capacitor, connected between a common contact of said RF filter and said biasing resistor, and one of said source or said emitter; and

h) a first coupling capacitor, connected to the ungrounded contact of said first impedance, for coupling the voltage developed across said first impedance, the polarity of which being similar to the polarity of said DC power supply.

7. Apparatus according to claim 6, further comprising:

a) a second impedance, connected in series between the RF filter and the DC power supply; and

b) a second coupling capacitor, connected to a common contact between said second impedance and said RF fillet for coupling the voltage developed across said second impedance, the polarity of which being opposite to the polarity of said DC power supply.