Voltage-to-current conversion

A differential voltage-to-current conversion circuitry, comprising:

• a power supply node for connection to a power supply voltage source;
• a first current path extending from the power supply node via a first intermediate node to a first load node to provide a first load current at the first load node for use by load circuitry when connected to the first load node, wherein a first supply-connection impedance is connected along the first current path between the power supply node and the first intermediate node and a first load-connection impedance is connected along the first current path between the first intermediate node and the first load node;
• a second current path extending, in parallel with the first current path, from the power supply node via a second intermediate node to a second load node to provide a second load current at the second load node for use by the load circuitry when connected to the second load node, wherein a second supply-connection impedance is connected along the second current path between the power supply node and the second intermediate node and a second load-connection impedance is connected along the second current path between the second intermediate node and the second load node;
• a differential voltage input connected between the first and second intermediate nodes via first and second input-connection impedances, respectively, for application of a differential input voltage signal, supplied at the differential voltage input, between the first and second input-connection impedances so that the first and second load currents together define a differential current signal dependent on the differential input voltage signal;
• a first current sink connected to the first load node so as to draw a first sink current from the first load node;
• a second current sink connected to the second load node so as to draw a second sink current from the second load node;
• and
• control circuitry,
• wherein:
• the first and second load-connection impedances are implemented as first and second transistors, respectively;
• the control circuitry is configured to control a bias voltage provided to the gate or base terminals of the first and second transistors so as to control a gain relationship between the differential input voltage signal and the differential current signal;
• the first and second load currents comprise respective component currents of the differential current signal superimposed on a load bias current;
• the first and second current sinks are controllable current sinks;
• and
• the control circuitry is configured to control the load bias currents by controlling the first and second sink currents.