Tunable differential-input gallium arsenide transconductors

Three architectures are proposed for differential input transconductors which make use of a recently proposed current mirror and which provide simple transconductance tuning by control of a differential-pair tail current. Measured results confirm the linearity of the current mirror and simulation is used to evaluate the transconductors. One architecture having a high degree of symmetry is advantageous from the points of view of low feedthrough of the control signal, good linearity, wide differential-mode bandwidth and high common-mode rejection ratio.