Tunable high-frequency Gm-C filters

We consider known, modified, and new transistor circuits for transconductor s and some theory on their application in integrated tunable Gm-C or transc onductor-capacitor filters for high frequencies. The circuits are balanced and mostly complementary. They use bipolar (NPN and VPNP) and/or CMOS trans istors. The low delay and low input capacitance of the newer circuits makes them particularly suitable for very high frequencies, in the hundreds of m egahertz. The relatively high power efficiency and low noise lead to a low power consumption in combination with a high signal-to-noise ratio. Their s implicity results in a small chip area and hence in low cost. The partly ne w theory is on noise, sensitivities, quality factors, linearization, power and power efficiencies.