Patent ID: 7652509
Filing Date: 2010-01-26
Classification: H03F

Abstract:
1. A transconductance circuit to convert a differential input voltage, supplied as two signals on two inputs, into a differential output current, characterized in that, where each of the two signals of said differential input voltage is supplied to each input through a follower transistor connected to said input by its emitter and receives said signal on a control electrode, each of the two inputs of the transconductance circuit is connected to a respective current source that is dynamically controlled by the other input of the transconductance circuit, said current source being such that the current supplied to each input by said current source eliminates current variations caused by voltage variations of the input voltage signal, wherein the transconductance circuit comprises two sides, each side comprising an input, an output, at least a first transistor having a control electrode coupled for receiving a bias voltage, a first electrode connected to said output and a second electrode connected to said input through a resistor, a second transistor having a first electrode and a control electrode in common to said input and a second electrode connected to a power supply terminal, and wherein the first and second transistors of the first side are different from the first and second transistors of the second side.