Powered transducer preamplifier with DC level shifting circuit
AssigneeUpState Audio
InventorMatthew M. Lesko
Life of this patent
Estimating the term…
Abstract
A powered transducer preamplifier includes a preamplifier circuit that DC couples the preamplifier input with the preamplifier output. A biasing circuit is coupled to the preamplifier input to apply a bias voltage to power the transducer, and a DC level shifting circuit is DC coupled to the signal path of the preamplifier circuit between the input and the output to compensate for this bias voltage. The DC level shifting circuit avoids the use of reactive components, and thereby reduces phase distortion. A variety of DC level shifting circuits can be used, including a bridge circuit having four matched resistors and an inverter DC coupled between the nodes of the bridge.
Claims51
A powered transducer preamplifier comprising:
- a preamplifier circuit comprising a transducer input, a preamplifier output, and a preamplifier signal path that DC couples the input and the output;
- a biasing circuit coupled to the input to apply a bias voltage to the input;
- and
- a DC level shifting circuit DC coupled to the signal path between the input and the output and operative to compensate for the bias voltage.
A powered transducer preamplifier comprising:
- first and second transducer input nodes;
- a biasing circuit operative to apply a bias voltage to both of the transducer input nodes;
- a preamplifier circuit comprising a preamplifier output node and first and second preamplifier input nodes DC coupled with the first and second transducer input nodes, respectively, said transducer input nodes and preamplifier circuit included in a preamplifier signal path that DC couples the transducer input nodes and the preamplifier output node;
- at least one resistor DC coupled with one of the nodes in the signal path;
- and
- at least one current sink DC coupled with signal path downstream of the resistor.
A powered transducer preamplifier comprising:
- first and second transducer input nodes;
- a biasing circuit operative to apply a bias voltage to both of the transducer input nodes;
- a preamplifier circuit comprising first and second preamplifier input nodes DC coupled with the first and second transducer input nodes, said preamplifier circuit comprising first and second balanced signal paths;
- a bridge circuit comprising first and second bridge nodes;
- first and second resistors DC coupled between the first signal path and the first and second bridge nodes, respectively;
- third and fourth resistors DC coupled between the second signal path and the first and second bridge nodes, respectively;
- and an inverter DC coupled between the first and second bridge nodes.
A powered transducer preamplifier comprising:
- a preamplifier circuit comprising a transducer input, a preamplifier output, and a preamplifier signal path that DC couples the input and the output;
- a biasing circuit coupled to the input to apply a bias voltage to the input;
- and
- a DC level shifting circuit DC coupled to the signal path between the input and the output and operative to compensate for the bias voltage, the DC level shifting circuit comprising non-reactive circuit elements configured to maintain an input portion of the preamplifier circuit in Class A operation and avoid signal phase shift, whereby crossover distortion of the input portion of the preamplifier circuit is reduced.
Dependencies are inferred from the claim text.