Circuit technique that sets transconductance

A BiCMOS differential transconductor having a pair of inputs and a controllable transconductance, the transconductor comprising:

• a. positive power supply voltage;
• b. a first and a second p-channel MOS transistor, wherein a source of each of the first and the second p-channel MOS transistors is coupled to the supply voltage;
• c. means for forming a first biasing voltage coupled to a gate of the first p-channel MOS transistor and a gate of the second p-channel MOS transistors;
• d. a first and a second npn bipolar transistor, wherein a collector of the first npn transistor is coupled to a drain of the first p-channel MOS transistor and a collector of the second npn transistor is coupled to a drain of the second p-channel transistor;
• e. means for forming a second biasing voltage coupled to a base of the first npn transistor and to a base of the second npn transistor;
• f. a first and a second n-channel MOS transistor, wherein a drain of the first n-channel MOS transistor is coupled to an emitter of the first npn transistor and a drain of the second n-channel MOS transistor is coupled to an emitter of the second npn transistor;
• g. a current source, having a current value, coupled differeritially to the transconductor;
• h. a resistor voltage divider, for providing a voltage value, coupled to the pair of inputs;
• and
• i. a resistor having a controllable resistance value coupled for controlling a current flowing through the voltage divider
• wherein the transconductance is proportional to a ratio of the current value to the voltage value and is proportional to an inverse of the resistance value.