Class A Amplifier with 2 Independent Gain Blocks GP509 DATA SHEET FEATURES DESCRIPTION • low amplifier current (typical 105 µA) 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. • low noise and distortion • 1.0 to 5 VDC operating range • independent preamplifier 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. • Class A output stage • variable transducer current • 4.0 kΩ microphone decoupling resistor, on-chip STANDARD PACKAGING • 8 pin MICROpac • 8 pin PLID ® 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. • 8 pin SLT • Chip (61 x 55 mils) VB 5 VMIC 4 RMIC 21k 3 A IN 6 - A - B 7 B OUT RE RE 1 A OUT 8 B IN 2 GND BLOCK DIAGRAM Revision Date: January 1996 GENNUM CORPORATION P.O. Box 489, Stn A, Burlington, Ontario, Canada L7R 3Y3 Japan Branch: A-302, M i yamae Vi l l age, 2–10–42 M i yamae, Suginami–ku, Tokyo 168, Japan Document No. 510 - 71 - 04 tel. (905) 632-2996 fax: (905) 632-2055 tel. (03) 3247-8838 fax (03) 3247-8839 ABSOLUTE MAXIMUM RATINGS PIN CONNECTION PARAMETER VALUE / UNITS Supply Voltage 5V DC Power Dissipation 25 mW o V MIC o Operating Temperature -10 to + 40 C Storage Temperature -20o to + 70oC 5 4 VB A IN B OUT GND RE 1 A OUT B IN 8 CAUTION CLASS 1 ESD SENSITIVITY ELECTRICAL CHARACTERISTICS Supply Voltage = +1.3 VDC, Frequency = 1 kHz, Temperature = 25o C PARAMETER SYMBOL CONDITIONS MIN TYP Amplifier Current IAMP Transducer Current ITRANS RE = 55 105 225 300 375 µA Maximum Transducer Current ITRANS(MAX) RE = 0 Ω 2 - - mA Voltage Gain AV S1 = b VOUT= 500 mVRMS 58 61 64 dB Harmonic Distortion THD S1 = b VOUT = 500 mVRMS - 1 4 % Input Referred Noise IRN NFB 0.2 to 10 kHz at 12dB/Oct - 1 2 µV RMS Stable with Battery Resistance Resistance (RB) to: Stability RB = 22 Ω - - 22 Ω Input Bias Current IBIAS RFA = 1M -50 0 50 nA Microphone Resistance RMIC 3 4 5 kΩ Emitter Bias Voltage (Pin 7) VRE - 30 - mV On Chip Emitter Resistor RE - 100 - Ω A Output Current Capability (Pin 1) IOUT - 30 - µA ∞ Note: All parameters and switches as shown in Test Circuit unless otherwise stated in CONDITIONS column R B = 4.7 1.3 VDC 5 RMIC VOUT 4 RL = 1k 21k VIN a S1 RS 3k3 CS 1.0 b 6 - B - A 3 7 RE 1 8 2 RE =27.5 1 kHz R FA =100k 1.0 All external resistors in ohms & ± 1% tol., all capacitors in farads & ± 10% tol. unless otherwise stated Fig. 1 Test Circuit 510 - 71 - 04 2 MAX UNITS 150 µA VB 5 VMIC RMIC 4 21k 6 3 - A A IN - B 7 B OUT RE RE 1 2 8 GND B IN A OUT Fig. 2 Functional Schematic V =1.3VDC B 5 RMIC 1.0 4 ED1913 RLAC 21k Rs 3k9 CS 0.22 3 - A - B 6 7 RE 8 1 2 82 100k RVC All resistors in ohms, all capacitors in farads unless otherwise stated. Gain of Stage A = 20 Log 10 Gain of Stage B = 20 Log RVC 10 RLAC // 21K RE // 82 RS Fig. 3 Typical Hearing Aid Circuit 3 510 - 71 - 04 10 4 0 2 RVC = 100k -10 0 CS = 0.22µ -20 R VC = 47k OUTPUT (dBV) OUTPUT (dBV) -2 RVC = 22k -30 -40 R -50 -60 R -70 VC VC = 10k = 3.3k CS = 0.1µ -4 CS = 0.047µ -6 -8 -10 -12 CS = 0.033µ -14 -16 -80 -18 -90 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -20 20 200 5 60 0 55 -5 50 -10 -15 45 40 -20 35 -25 30 -30 25 -35 20 0.8 0.9 1.0 1.1 1.2 1.3 1.4 10 100 RELATIVE AMPLIFIER CURRENT (µA) RELATIVE TRANSDUCER CURRENT (µA) 15 10 5 0 -5 -10 -15 -20 -10 0 10 20 30 10K 100K Fig.7 Preamplifier Open Loop Frequency Response Fig.6 Gain vs Supply Voltage -20 1K FREQUENCY (Hz) SUPPLY VOLTAGE (V) -25 20k Fig. 5 Closed Loop Frequency Response for Various CS Values GAIN (dB) RELATIVE GAIN (dB) Fig.4 I/O Characteristics for Various Gain Settings 0.7 2k FREQUENCY (Hz) INPUT (dBV) 40 50 20 15 10 5 0 -5 -10 -15 -20 -25 -30 -20 -10 0 TEMPERATURE (O C) 10 20 30 40 TEMPERATURE (O C) Fig. 8 Transducer Current vs Temperature Fig. 9 Amplifier Current vs Temperature DOCUMENT IDENTIFICATION PRODUCT PROPOSAL This data has been compiled for market investigation purposes only, and does not constitute an offer for sale. ADVANCE INFORMATION NOTE This product is in development phase and specifications are subject to change without notice. Gennum reserves the right to remove the product at any time. Listing the product does not constitute an offer for sale. REVISION NOTES PRELIMINARY DATA SHEET The product is in a development phase and specifications are subject to change without notice. Au bump removed Gennum Corporation assumes no responsibility for the use of any circuits described herein and makes no representations that they are free from patent infringement. © Copyright 1989 Gennum Corporation. 510 - 71 - 04 All rights reserved. Printed in Canada. 4 DATA SHEET The product is in production. Gennum reserves the right to make changes at any time to improve reliability, function or design, in order to provide the best product possible. 50