GP509

Class A Amplifier with 2 Independent Gain Blocks GP509 DATA SHEET FEATURES low amplifier current (typical 105 µA) low noise and distortion 1.0 to 5 VDC operating range www.DataSheet4U.com DESCRIPTION The GP509 is a Class A amplifier utilizing Gennum’s proprietary low voltage JFET technology. It consists of a singleended, low noise inverting gain block, a Class A output stage, and an on-chip microphone decoupling resistor. Block A typically has an open loop voltage gain of 56 dB, with the closed loop gain set by the ratio of the feedback resistor to the source impedance. It is recommended that the maximum closed loop gain be 20 dB lower than the open loop gain. All blocks of the device are internally bias compensated, preventing any DC current flow via external feedback resistors. Without this compensation, audible scratchiness would be present during changes in volume control settings. The output stage of the GP509 is a Class A current drive. It has a fixed reference voltage of typically 30 mV at pin 7 of the device. The current that flows in the transducer is the ratio of the 30 mV reference voltage and the on-chip emitter resistor (RE). To increase the bias current in the transducer, simply place an external RE resistor from pin 7 to ground, thereby decreasing the equivalent emitter resistance and increasing the current. independent preamplifier Class A output stage variable transducer current 4.0 kΩ microphone decoupling resistor, on-chip STANDARD PACKAGI...