A transconductance as such performs the function of converting a signal input voltage to a signal output current. While such a function can be performed for some purposes by a single device, such as a single resistor or a MOSFET (metal-oxide-semiconductor field-effect transistor), for applications requiring a monolithic integrated filter circuit with relatively high precision for signals with frequencies above the audible range a more complex transconductance network is generally required in order to avoid or reduce degradations of the output due to non-linearity, phase lag, transistor thermal noise, and noise from other sources, such as the supply voltage nodes. Telecommunications receiving and other equipment often includes an integrated circuit tunable active filter, such as for example a biquad Butterworth filter, which relies upon relatively high precision and broadband transconductance networks that can be controlled continuously by means of an applied voltage or current to set its transfer function. There is a need for such transconductance networks which have a high degree of linearity and low phase shift at relatively high signal frequencies.