An apparatus is disclosed for implementing a complex filter of the type represented by a transfer function having a complex pole. The apparatus is capable of creating real and imaginary parts, Y.sub.r and Y.sub.i, of a complex output signal in response to receiving real and imaginary parts, X.sub.r and X.sub.i, of a complex input signal. The apparatus comprises a plurality of variable resistors that may be tuned to adjust various operating parameters of the complex filter.