Feed forward cancellation amplifier utilizing dynamic vector control

A feed forward cancellation amplifier having a main amplifier, and an error amplifier whose response is to be tested, comprising:

• means for applying a test signal of predetermined frequency to the input of the main amplifier, and deriving a residual test signal from the output of the main amplifier;
• a vector modulator having an input and an output, and including a pair of voltage controllable attenuators;
• means for applying an error signal to said input of said vector modulator so as to produce a modified error signal at said output thereof;
• an I & Q network having two inputs, and also including a pair of mixers having outputs coupled to respective ones of said voltage controllable attenuators in said vector modulator, for modifying the error signal;
• means for applying said residual test signal to one input of said I & Q network;
• and
• means for applying the test signal to the other input of said I & Q network, for mixing with said residual test signal at said predetermined frequency to thereby control the modification of the error signal.

In a feed forward cancellation amplifier system for amplifying radio frequency telephony signals which includes a main amplifier, an error correction circuit producing a message error signal, an error amplifier for producing an amplified message error signal that is then subtracted from the amplified and distorted message signal output of the main amplifier prior to a final output circuit, and a negative feedback circuit responsive to a test signal for compensating and minimizing variation or drift in the operation of the error amplifier, the improvement comprising:

• said error correction circuit including a vector modulator responsive to modified quadrature vector components of said message error signal for producing a single voltage vector error signal;
• said negative feedback circuit including an I & Q network for modifying said quadrature vector components of said error signal in said error correction circuit;
• and
• wherein said vector modulator includes PIN diode circuits forming attenuators for modifying said quadrature vector components of said message error signal.

In a feed forward cancellation amplifier system for amplifying radio frequency telephony signals which includes a main amplifier, an error correction circuit producing a message error signal, an error amplifier for producing an amplified message error signal that is then subtracted from the amplified and distorted message signal output of the main amplifier prior to a final output circuit, test signal generating means for supplying a test signal to said main amplifier so as to produce a residual test signal at the final output circuit, and a negative feedback circuit responsive to the residual test signal for compensating and minimizing variation or drift in the operation of the error amplifier, the improvement comprising:

• circuit means for breaking the message error signal into quadrature vector components;
• said negative feedback circuit including an I & Q network coupled to both the test signal generating means and the final output circuit and responsive to the residual test signal for producing quadrature control signals;
• and
• circuit means including a vector modulator responsive to said quadrature control signals for dynamically and independently controlling the amplitudes of said quadrature components of said error signal and combining them into a single voltage vector error signal which is then supplied to said error amplifier.