Current control mechanism for low voltage applications
View Patent ↗A current control mechanism for use in low power consumption circuits with limited headroom includes a differential transistor pair from whose collectors a current output is taken. The current output is a function of a reference voltage provided at bases of a reference transistor pair having emitters that are coupled to the bases of the differential pair. The reference voltage is controlled by a pair of control transistors that control current through a load. A pair of tracking transistors can be provided to track supply voltage. A single-ended topology can also be implemented.
1. A current control circuit for a broadband amplifier, the circuit comprising:
an output transistor for supplying an output current at an output node coupled to the emitter of the transistor;
a reference transistor having a reference node at a base thereof, the reference transistor being coupled between a voltage supply and a base of the output transistor;
a current source configured to supply current through the reference node; and
a control transistor configured to control a voltage of the reference node by controlling current through a load that is coupled to the reference node.
2. The circuit of claim 1 , further comprising a tracking transistor coupled to the reference node, the tracking transistor varying current through the reference node based on variations in voltage from the voltage supply.
3. The circuit of claim 1 , wherein at least one of the transistors is an InGaP device.
4. The circuit of claim 1 , wherein the current source is a current mirror coupled to the reference node.