| 摘要 |
An inductorless voltage biasing circuit is provided for an AC-coupled amplifier (10) of the type having a signal input terminal (VIN) and a coupling capacitor (12) for coupling the input terminal (VIN) to a control terminal (16) of the AC-coupled amplifier (10). The voltage biasing circuit includes a voltage source (VB) coupled to the control terminal (16), with the voltage biasing circuit including a differential-input amplifier (18) having a noninverting input coupled to the voltage source (VB), an inverting input, an output terminal (20) and a differential voltage gain characteristic that decreases as a function of frequency. A resistor (22) is coupled between the inverting input and the output terminal (20), and the control terminal (16) of the AC-coupled amplifier is coupled to the inverting input of the differential-input amplifier (18). In this manner, a low-impedance DC-voltage biasing source is provided for an AC-coupled amplifier without using an inductor.
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