Abstract: A feedforward amplifier circuit includes a controllable error signal subtraction module (CESSM). The CESSM has a module signal input, an error cancellation input, a module control input and a circuit output. The module signal input of the CESSM is coupled to a power amplifier via a coupler and delay circuit. The error cancellation input is coupled to a feedforward subtraction module via an error signal amplifier. The module control input is coupled to the output of a controller. In operation, the CESSM subtracts an error cancellation signal from the module signal input. Upon determining a malfunction of the power amplifier, the controller sends a signal to the module control input resulting in the CESSM isolating the module signal input from the circuit output and directly coupling the error cancellation to the circuit output.