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Class A Amplifier with 2 Independent Gain Blocks
GP509 DATA SHEET
FEATURES * low amplifier current (typical 105 A) * low noise and distortion * 1.0 to 5 VDC operating range * independent preamplifier * Class A output stage * variable transducer current * 4.0 k microphone decoupling resistor, on-chip STANDARD PACKAGING * 8 pin MICROpac * 8 pin PLID (R) * 8 pin SLT * Chip (61 x 55 mils)
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.
VB 5 VMIC 4 RMIC 21k 3 A IN 6
-A
-B
7 RE 1 A OUT 8 B IN 2 GND
B OUT RE
BLOCK DIAGRAM
Revision Date: January 1996
Document No. 510 - 71 - 04
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
tel. (905) 632-2996 fax: (905) 632-2055
tel. (03) 3247-8838 fax (03) 3247-8839
ABSOLUTE MAXIMUM RATINGS
PARAMETER Supply Voltage Power Dissipation Operating Temperature Storage Temperature
o
PIN CONNECTION
VALUE / UNITS 5V DC 25 mW -10 to + 40 C -20o to + 70oC
o
V MIC A IN GND A OUT
4
5
VB B OUT RE
1
8
B IN
CAUTION CLASS 1 ESD SENSITIVITY
ELECTRICAL CHARACTERISTICS
Supply Voltage = +1.3 VDC, Frequency = 1 kHz, Temperature = 25o C
PARAMETER Amplifier Current Transducer Current Maximum Transducer Current Voltage Gain Harmonic Distortion Input Referred Noise Stable with Battery Resistance Resistance (RB) to: Input Bias Current Microphone Resistance Emitter Bias Voltage (Pin 7) On Chip Emitter Resistor A Output Current Capability (Pin 1)
SYMBOL IAMP ITRANS ITRANS(MAX) AV THD IRN Stability IBIAS RMIC VRE RE IOUT RE =
CONDITIONS
MIN 55
TYP 105 300 61 1 1 0 4 30 100
30
MAX 150 375 64 4 2 22 50 5 -
UNITS A A mA dB % V RMS nA k mV
A
225 2 58 -50 3 -
RE = 0 S1 = b VOUT= 500 mVRMS S1 = b VOUT = 500 mVRMS NFB 0.2 to 10 kHz at 12dB/Oct RB = 22 RFA = 1M
Note: All parameters and switches as shown in Test Circuit unless otherwise stated in CONDITIONS column
R B = 4.7 1.3 VDC
RMIC 4 VIN
5
VOUT RL = 1k 6
21k a b S1 -A 3 7 RE 1 1 kHz R FA =100k 1.0 8 2 RE =27.5 -B
RS 3k3
CS 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
VB 5 VMIC 4 RMIC 21k 3 A IN 6
-A
-B
7 RE 1 A OUT 8 B IN 2 GND
B OUT RE
Fig. 2 Functional Schematic
V =1.3VDC
B
5 RMIC 1.0 4 21k 3 ED1913 RLAC
-A
-B
6
Rs
3k9
CS 0.22
7 RE 1 100k RVC
All resistors in ohms, all capacitors in farads unless otherwise stated.
8
2
82
Gain of Stage A = 20 Log
10
RVC RS
Gain of Stage B = 20 Log
10
RLAC // 21K RE // 82
Fig. 3 Typical Hearing Aid Circuit
3
510 - 71 - 04
10 0 -10 RVC = 100k
4 2 0 -2 CS = 0.22 CS = 0.1 CS = 0.047
OUTPUT (dBV)
OUTPUT (dBV)
-20 -30 -40
R
VC
= 47k RVC = 22k
-4 -6 -8 -10 -12 -14 -16 -18
R -50 -60 -70 -80 -90 -130 -120 -110 -100 -90 -80 -70 -60 R = 3.3k
VC
= 10k
CS = 0.033
VC
-50
-40
-30
-20
-20
20
200
2k
20k
INPUT (dBV)
FREQUENCY (Hz)
Fig.4 I/O Characteristics for Various Gain Settings
Fig. 5 Closed Loop Frequency Response for Various CS Values
60 55 50
5 0
RELATIVE GAIN (dB)
-5 -10 -15 -20 -25 -30 -35 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4
GAIN (dB)
45 40 35 30 25 20
10
100
1K
10K
100K
SUPPLY VOLTAGE (V)
FREQUENCY (Hz)
Fig.6 Gain vs Supply Voltage
RELATIVE TRANSDUCER CURRENT (A) RELATIVE AMPLIFIER CURRENT (A)
-20 -10 0 10 20 30 40 50 15 10 5 0 -5 -10 -15 -20 -25
Fig.7 Preamplifier Open Loop Frequency Response
20 15 10 5 0 -5 -10 -15 -20 -25 -30 -20 -10 0 10 20 30 40 50
TEMPERATURE (O C)
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
Au bump removed
PRELIMINARY DATA SHEET The product is in a development phase and specifications are subject to change without notice. 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.
Gennum Corporation assumes no responsibility for the use of any circuits described herein and makes no representations that they are free from patent infringement. (c) Copyright 1989 Gennum Corporation. All rights reserved. Printed in Canada.
510 - 71 - 04
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