Continuous-Time Analog Two-Dimensional IIR Beam Filters

Analog filter circuits that are realized in continuous-time discrete-space domain are proposed for implementing 2-D infinite impulse response (IIR) spatiotemporal transfer functions having beam-shaped passbands. These filters may be used for analog beamforming applications including seismic, audio, sonar, and ultrasonic signal processing. Unlike digital implementations, the proposed 2-D analog beam filters avoid the need for A/D conversions and digital circuitry. Importantly, the beam distortion (beam squint) due to bilinear transformation that is unavoidable in digital 2-D IIR beam filters is significantly reduced. A demonstrative example using operational amplifiers for first-order analog filters is provided.