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Relatively high transconductance in bipolar devices contributes to the economy of power dissipation on analog integrated circuits. Recently, a high-speed transistor, such as the HBT attracts attention of researchers and developers in electronic communication industries and is expected to be applied to RF circuits. In this paper, high-efficiency bipolar transconductors are presented. The proposed circuits are composed of a hyperbolic function circuit with an intermediate voltage terminal and a triple-tail cell. The parameter values for linearisation are all integers. The values can be realised precisely. The linearity of the proposed transconductors is superior to the triple-tail cell. The linear input range is 1.5 times as wide as that of the conventional triple-tail cell. Nevertheless, the power dissipation is lower than the triple-tail cell. Further, sensitivity analysis shows that the proposed transconductors have lower sensitivity than the triple-tail cell. These properties are confirmed by SPICE simulation. [ABSTRACT FROM AUTHOR]

A transconductor is a basic building for integrated analogue circuits. High linearity of the transfer characteristic is necessary to a transconductor. However, along with miniaturisation of a device, linearity of the transconductor has deteriorated because of the mobility degradation from an effect of a vertical electric field. This paper proposes a new technique to reduce the influence of mobility degradation and to improve linearity of a transconductor. In order to improve the linearity, a source-coupled pair is combined with the transconductor. It is confirmed that the proposed technique reduces the transconductance error by about 1/5. For a sinusoidal input voltage of 1 Vp-p and 1 MHz, the total harmonic distortion is 3% or less. [ABSTRACT FROM AUTHOR]