FEED-FORDWARD AMPLIFIER

• US 3,649,927 A
• Filed: 02/27/1970
• Issued: 03/14/1972
• Est. Priority Date: 02/27/1970
• Status: Expired due to Term

• Current Assignee: Harold Seidel
• Original Assignee: Harold Seidel
• Inventors: Seidel, Harold
• Primary Examiner(s): Lake, Roy
• Assistant Examiner(s): Mullins, James B.
• Application Number:
  US05/015,002
• Time in Patent Office: 746 Days
• Field of Search: 330/124,149,151 325/65,474-476 333/10 328/163
• US Class Current: 330/124.00R
• CPC Class Codes: H03F 1/3229 using a loop for error extraction and another loop for error subtraction

Abstract

The parameters of a feed-forward compensated amplifier are redefined such that the error correcting signal and the uncorrected signal combine in phase at maximum output power. It is then shown that for this condition a directional coupler can be used as the error injection network with minimal loss of error signal power or main signal power. This results in the most efficient use of both the main signal amplifier and the error signal amplifier and, in addition, produces an impedance match in the main signal wavepath, in the error signal wavepath and at the output terminal of the overall amplifier.

Claims

1. A feed-forward amplifier for electromagnetic wave signals comprising:

first and second parallel wavepaths;

the first of said wavepaths including, in cascade, a main signal amplifier and a first time delay network;

the second of said wavepaths including, in cascade, a second time delay network and an error amplifier;

means for dividing an input signal into two signal components, and for coupling a different one of said components to the input end of each of said wavepaths;

means for coupling a portion of the output from said main signal amplifier to the input of said error amplifier; and

an error injection network comprising a directional coupler for combining the signal in said two wavepaths in time and phase to minimize error components in the amplifier output signal;

characterized in that;

the parameters of said dividing means, said coupling means and said injection network are proportioned such that all of the signal energy from said two wavepaths combine in phase in the output port of said coupler at some specified high level output signal.

2. The feed-forward amplifier according to claim 1 wherein:

said coupler has two pair of conjugate ports 1-2 and 3-4;

the signal in said first wavepath is coupled to port 1;

the signal in said second wavepath is coupled to port 2;

the output signal is obtained from port 3; and

wherein the coupler parameters S13 and S23 are given by where Pm is the maximum power output from said main signal amplifier;

P is the maximum power output from said error amplifier;