Amplification circuit and hearing aid
Certain embodiments of the present technology provide improved amplification circuits and hearing aids that can utilize such amplification circuits. In an embodiment, for example, an amplification circuit includes: a first sub circuit configured to create a voltage drop when a supply voltage is above a first voltage; and a second sub circuit configured to create a reverse voltage drop when the supply voltage is below a second voltage, wherein the first and second sub circuits operate to maintain idling current within a range. Certain embodiments of the present technology also provide hearing aids that include removable dampers.
1. An amplification circuit comprising:
a first sub circuit configured to create a voltage drop across a plurality of resistors of an amplification sub circuit when a supply voltage is above a first voltage; and
a second sub circuit configured to create a reverse voltage drop across the plurality of resistors of the amplification sub circuit when the supply voltage is below a second voltage,
wherein the first and second sub circuits operate to maintain idling current within a range at the amplification sub circuit.
2. The amplification circuit of claim 1 comprising a plurality of transistors, wherein the voltage drop across the plurality of resistors is such that a base emitter voltage of the plurality of transistors is independent of supply voltage above the first voltage.
3. The amplification circuit of claim 1 comprising a plurality of transistors, wherein the reverse voltage drop across the plurality of resistors is such that a base emitter voltage of the plurality of transistors is independent of supply voltage below the second voltage.
4. The amplification circuit of claim 1 , wherein the second sub circuit is disabled when the supply voltage is above a third voltage.
5. The amplification circuit of claim 4 , wherein the first voltage is about 1.35 volts, the second voltage is about 1 volt, and the third voltage is about 1.2 volts.
6. The amplification circuit of claim 1 , wherein the first sub circuit and the second sub circuit are provided on the same die and have the same temperature coefficient.
7. The amplification circuit of claim 1 , comprising a first output and a second output, wherein the outputs are configured to be used with a two-terminal receiver.
8. The amplification circuit of claim 7 , wherein the second output is configured to provide an output that is 180 degrees out of phase with the output provided by the first output.
9. The amplification circuit of claim 8 , wherein the circuit provides an output without the use of output capacitors.
10. The amplification circuit of claim 1 , wherein the circuit is configured to be used in a hearing aid.
11. A method for maintaining idling current of an amplification circuit within a range, the method comprising:
creating, by a first sub circuit, a voltage drop across a plurality of resistors of an amplification sub circuit when a supply voltage is above a first voltage; and
creating, by a second sub circuit, a reverse voltage drop across the plurality of resistors of the amplification sub circuit when the supply voltage is below a second voltage.
12. The method of claim 11 comprising a plurality of transistors, wherein the voltage drop across the plurality of resistors is such that a base emitter voltage of the plurality of transistors is independent of supply voltage above the first voltage, and wherein the reverse voltage drop across the plurality of resistors is such that a base emitter voltage of the plurality of transistors is independent of supply voltage below the second voltage.