Balanced Integrator Filters at Video Frequencies

Two balanced integrator video filters are presented. They are a choice from a series of experiments on silicon including filters, delay equalizers and oscillators. A 4MHz resonance circuit has been realized as an example of a purely bipolar implementation. It makes use of variable junction capacitors, fixed diffusion resistors and balanced transconductance amplifiers. A 5th-order elliptic low-pass filter has been realized in a BICMOS technology. The amplifiers are mainly bipolar while the NMOS resistors and gate-oxide capacitors make use of the CMOS part. These two examples show that high-performance, low-cost, integrated video filters can be realized with balanced integrators.