Gennum Corporation GP509 Datasheet



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

• independent preamplifier

• Class A output stage

• variable transducer current

• 4.0 k

Ω microphone decoupling resistor, on-chip

STANDARD PACKAGING

• 8 pin MICROpac

• 8 pin PLID

®

• 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 (R
simply place an external R
thereby decreasing the equivalent emitter resistance and

). To increase the bias current in the transducer,

E

resistor from pin 7 to ground,

E

increasing the current.

V

B

5

R

V

MIC

A IN

4

3

MIC


21k

6

-

A

A OUT

1

B IN

-

B

R

E

8

2

GND

B OUT

7

R

E

BLOCK DIAGRAM

Revision Date: January 1996

GENNUM CORPORATION P.O. Box 489, Stn A, Burlington, Ontario, Canada L7R 3Y3 tel. [phone] fax: [phone]

Japan Branch: A-302, Miyamae Vi llage, 2–10–42 Mi yamae, Suginami–ku, Tokyo 168, Japan tel. [phone] fax [phone]

Document No. 510 - 71 - 04

ABSOLUTE MAXIMUM RATINGS

PIN CONNECTION

PARAMETER VALUE / UNITS
Supply Voltage 5V DC
Power Dissipation 25 mW
Operating Temperature -10o to + 40oC
Storage Temperature -20o to + 70oC

V

MIC

A IN
GND

A OUT

4

1

5

V

B

B OUT
R

E

B IN

8

CAUTION

CLASS 1 ESD SENSITIVITY

ELECTRICAL CHARACTERISTICS

Supply Voltage = +1.3 VDC, Frequency = 1 kHz, Temperature = 25oC

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Amplifier Current I

Transducer Current I

Maximum Transducer Current I

Voltage Gain A

Harmonic Distortion THD S1 = b V

AMP

TRANS

TRANS(MAX)

V

R

= ∞ 225 300 375 µA

E

RE = 0 Ω 2 - - mA

S1 = b V

= 500 mVRMS 58 61 64 dB

OUT

= 500 mVRMS - 1 4 %

OUT

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 I

Microphone Resistance R

Emitter Bias Voltage (Pin 7) V

On Chip Emitter Resistor R

A Output Current Capability (Pin 1) I

Note: All parameters and switches as shown in Test Circuit unless otherwise stated in CONDITIONS column

BIAS

MIC

RE
E

OUT - 30 - µA

RFA = 1M -50 0 50 nA

55 105 150 µA

3 4 5 kΩ

- 30 - mV

- 100 - Ω

510 - 71 - 04

R

MIC

5

4

V

IN

R

S

3k3

1 kHz

All external resistors in ohms & ±1% tol., all capacitors in farads & ±10% tol. unless otherwise stated

C

1.0

a

S1

b

S

- A

3

R =100k

FA

1

8

1.0

21k

- B

Fig. 1 Test Circuit

2

R

B

= 4.7

1.3 VDC

V

OUT

R

= 1k

L

6

7

R

E

2

R =27.5

E