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Gennum |
Class A Amplifier with 2 DC Coupled
Gain Blocks & Schottky Diodes
GK509 DATA SHEET
FEATURES
• 100 µA typical current drain
• low noise and distortion
• 1.0 to 5 VDC operating range
• DC coupled stages
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• Class A output stage
• Schottky diodes for MPO control
• variable transducer current
• 4 kΩ microphone decoupling resistor
STANDARD PACKAGING
• 8 pin PLID®
• Chip ( 61 x 55 mils)
VMIC
5
RMIC
DESCRIPTION
The GK509 is a Class A amplifier utilizing Gennum’s
proprietary low voltage JFET technology. It consists of a
single-ended, low noise inverting gain block, a Class
A output stage, an on-chip microphone decoupling
resistor, and a pair of Schottky diodes for symmetrical
peak clipping.
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 GK509 is a Class A current drive.
It has a fixed reference voltage of typically 30 mV at pin 2
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 2
to ground, thereby decreasing the equivalent emitter resistance
and increasing the current.
The GK509 also contains a pair of Schottky diodes in the
feedback configuration of the output stage, which provides
approximately 12 dB of MPO control.
VB
6
MPO
7
21K
A IN
4
-A
-B
RE
B OUT
8
2 RE
31
A OUT
GND
All resistors in ohms, all capacitors in farads unless otherwise stated
Revision Date: January 2001
BLOCK DIAGRAM
Document No. 510 - 69 -06
GENNUM CORPORATION P.O. Box 489, Stn. A, Burlington, Ontario, Canada L7R 3Y3 tel. +1 (905) 632-2996
Web Site: www.gennum.com E-mail: [email protected]
ABSOLUTE MAXIMUM RATINGS
PIN CONNECTION
PARAMETER
Supply Voltage
Operating Temperature Range
Storage Temperature Range
VALUE/UNITS
5 V DC
-10°C to 40° C
-20°C to 70° C
A IN
A OUT
RE
GND
4
1
5 VMIC
VB
MPO
8 B OUT
CAUTION
CLASS 1 ESD SENSITIVITY
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ELECTRICAL CHARACTERISTICS
VP - Pin voltage measured with conditions as shown in Test Circuit.
Positive current corresponds to current INTO the pin.
Negative current corresponds with current OUT of the pin.
Conditions: Frequency = 1 kHz, Temperature = 25°C, Supply Voltage VB= 1.3 V
PARAMETER
SYMBOL
CONDITIONS
MIN
Amplifier Current
Transducer Current
Maximum Transducer Current
A Input Bias Voltage (pin 4)
A Input Bias Current (pin 4)
A O/P Voltage Swing-Hi (pin 3)
A Output Swing-Lo (pin 3)
A Open Loop Voltage Gain
B Output Sat. Voltage (pin 8)
A Output Current Capability
Diode Voltage Drop
Emitter Bias Voltage (pin 2)
On-chip Microphone Resistor
On-chip Emitter Resistor
Input Referred Noise
Harmonic Distortion
IAMP
ITRANS
ITRANS (MAX)
VBIAS A
IBIAS A
VOH A
VOL A
AOL
VSAT B
IOUT
VD
VRE
RMIC
RE
IRN
THD
VP2 = 0 V
RFA = 1 M, (Note 1)
VIN = 0.4 V DC, RFA = ∞,
IP3 = -10 µA (Note 2)
IIN = +1 µA, RFA = ∞,
IP3 = +10 µA (Note 3)
RL = 1 kΩ, VP2 = 0 V
(S2 = b), RL = ∞, (Note 4)
NFB 0.2 to 10kHz at 12 dB/Oct
500 mVRMS Output
55
170
2
500
-50
200
200
46
-
-
140
21.5
3
90
-
-
All parameters and switches remain as shown in Test Circuit unless otherwise stated in CONDITIONS column.
NOTES: 1. IBIAS A = (VP4 -VP4[RFA = 1M])/1M
2. VOH A = (VP3 -VP3 [VIN = 0.4VDC, RFA = ∞, IP3 = -10 µA])
3. VOL A = (VP3 -VP3 [IIN = +1µA, RFA = ∞, IP3 =+10 µA])
4. VD = (VP8 [Id = +(1.5 x ITRANS)] -VP8 [Id = +(0.5 x ITRANS)] )/2
TYP
100
230
-
570
0
580
280
56
100
30
265
30
4
125
1
1
MAX
145
290
-
650
50
-
UNITS
µA
µA
mA
mV
nA
mV
- mV
-
180
-
325
35.5
5
160
-
-
dB
mV
µA
mV
mV
kΩ
Ω
µVRMS
%
510 - 69 - 06
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