Two stage linear and low noise operational transconductance amplifier with low power supply voltage

摘要

A bipolar or MOS OTA is provided, in which no S/N degradation occurs due to compression and expansion of a signal, and low voltage operation can be realized at a power supply voltage of approximately 2 V for the input voltage range of approximately 1V peak-to-peak or greater. This OTA includes a first differential pair of first and second transistors Q1 and Q2 respectively driven by first and second current sources or sinks. A first resistor R1 is connected to emitters or sources of the first and second transistors. A differential input signal is applied across these emitters or sources. This OTA further includes a second differential pair of third and fourth transistors Q3 and Q4. A second resistor R2 is connected to emitters or sources of the third and fourth transistors. A current path is connected to the emitters or sources of the third and fourth transistors, thereby allowing a current to flow through the second resistor. The connection of the first and second pairs are so designed that each of the currents flowing through the third and fourth transistors contains a component proportional to the input signal. An output signal is derived from one of the emitters or sources of the third and fourth transistors.