Wide dynamic range transconductance stage

A wide dynamic range transconductance stage operative over an input voltage differential signal range, comprising:

• a pair of transconductance circuit branches for receiving a differential voltage,
• respective output locations associated with each branch,
• each branch comprising a pair of transconductance circuit paths to said output locations, each transconductance circuit path having a greater transconductance than the other transconductance circuit paths for its branch within a respective sub-range of said input voltage differential signal range, each transconductance circuit path dominating the other transconductance circuit paths for its branch within its respective input signal sub-range in establishing an overall transconductance for the transconductance stage, comprising a circuit path which dominates for higher input voltage differential signals within said input voltage differential signal range, and the other transconductance path of each branch comprising a bipolar transistor circuit, each bipolar transistor circuit comprising a bipolar transistor having a base and a collector-emitter circuit with its base receiving an input voltage signal, an impedance connected in series with its collector-emitter circuit, and a first current source connected to said collector-emitter circuit on the other side of said transistor from the impedance, the output from the branch being taken from said impedance, and
• an additional current source supplying current to the collector-emitter circuits of the bipolar transistors in each circuit path from the same side of said collector-emitter circuits as said first current sources, said bipolar transistors dividing the current from said additional current source in accordance with the input voltage differential signal applied to their bases.

A wide dynamic range transconductance stage operative over an input voltage differential signal range, comprising:

• positive and negative voltage buses,
• first and second bipolar transistors having respective bases and collector-emitter circuits, the bases of said bipolar transistors being connected to receive respective input voltage signals of an input voltage differential signal,
• first and second current sources connected between one of said voltage buses and one side of the collector-emitter circuits of said first and second bipolar transistors, respectively, to supply current to said bipolar transistors,
• first and second impedances connected between the other of said voltage buses and the other side of the collector-emitter circuits of said first and second bipolar transistors, respectively, such that outputs from said transconductance stage may be taken from said impedances,
• a third current source connected to said one voltage bus,
• third and fourth impedances connected to conduct respective currents between said third current source and the collector-emitter circuits for said first and second bipolar transistors, said respective currents accumulating with the currents supplied by said first and second current sources, said first and second bipolar transistors dividing the current from said third current source in accordance with the input voltage signals applied to their respective bases, and
• a first transconductance circuit connected in parallel with the circuit formed by said first bipolar transistor and said first current source circuit, and a second transconductance circuit connected in parallel with the circuit formed by said second bipolar transistor and said second current source circuit, said first and second transconductance circuits having a greater transconductance than said bipolar transistors for higher input voltage differential signals within said range, and a lesser transconductance than said bipolar transistors for lower input voltage differential signals within said range.

A wide dynamic range transconductance stage operative over an input voltage differential signal range, comprising:

• positive and negative voltage buses,
• first and second bipolar transistors having respective bases and collector-emitter circuits, the bases of said bipolar transistors being connected to receive respective input voltage signals of an input voltage differential signal,
• a first current source connected between one of said voltage buses and one side of the collector-emitter circuits of said first and second bipolar transistors to supply current to said bipolar transistors,
• first and second impedances connected between the other of said voltage buses and the other side of the collector-emitter circuits of said first and second bipolar transistors, respectively, such that outputs from said transconductance stage may be taken from said impedances,
• a second current source connected to said one voltage bus, and
• first and second transconductance elements connected between said second current source and said other sides of the first and second bipolar transistor collector-emitter circuits, respectively, said first and second transconductance elements having greater transconductances than said bipolar transistors for higher input voltage differential signals within said range, and lesser transconductances than said bipolar transistors for lower input voltage differential signals within said range, said first and second transconductance elements having controls which are connected in common with the bases of said first and second bipolar transistors, respectively, to receive said respective input voltage signals.