Low-voltage variable gain current amplifier for high-voltage signal processing

In low power-supply voltage systems, the method converting the input voltage signals into current signals by a resistor is useful in case that the amplitude of input voltage signals is larger than the supply voltage. This paper proposes a variable gain current amplifier as a current mode processing interface. The proposed circuit uses MOSFETs operated in the triode region to obtain a controllable current gain. High linearity is achieved by fixing the drain-to-source voltage of the MOSFETs. The proposed circuit is simulated by HSpice to confirm its performance. © 2009 The Institute of Electrical Engineers of Japan.