LMV1032
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SNAS233G – DECEMBER 2003 – REVISED MAY 2013
LMV1032-06/LMV1032-15/LMV1032-25 Amplifiers for 3-Wire Analog Electret Microphones
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FEATURES
DESCRIPTION
•
The LMV1032s are an audio amplifier series for small
form factor electret microphones. They are designed
to replace the JFET preamp currently being used.
The LMV1032 series is ideal for extended battery life
applications, such as a Bluetooth communication link.
The addition of a third pin to an electret microphones
that incorporates an LMV1032 allows for a dramatic
reduction in supply current as compared to the JFET
equipped electret microphone. Microphone supply
current is thus reduced to 60 µA, assuring longer
battery life. The LMV1032 series is specified for
supply voltages from 1.7V to 5V, and has fixed
voltage gains of 6 dB, 15 dB and 25 dB.
1
2
•
•
•
•
•
•
•
•
•
•
•
(Typical LMV1032-15, 1.7V Supply; Unless
Otherwise Noted)
Output Voltage Noise (A-weighted) −89 dBV
Low Supply Current 60 μA
Supply Voltage 1.7V to 5V
PSRR 70 dB
Signal to Noise Ratio 61 dB
Input Capacitance 2 pF
Input Impedance >100 MΩ
Output Impedance TA.
All limits are specified by design or statistical analysis.
Typical values represent the most likely parametric norm.
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1.7V and 5V Electrical Characteristics(1) (continued)
Unless otherwise specified, all limits ensured for TJ = 25°C and VDD = 1.7V and 5V. Boldface limits apply at the temperature
extremes.
Symbol
en
Parameter
Output Noise
VOUT
Min (2)
Conditions
A-Weighted
Output Voltage
VIN = GND
Typ (3)
LMV1032-06
−97
LMV1032-15
−89
LMV1032-25
−80
100
300
500
LMV1032-15
250
500
750
LMV1032-25
300
600
1000
Output Impedance
f = 1 kHz
IO
Output Current
VDD = 1.7V, VOUT = 1.7V, Sinking
0.9
0.5
2.3
VDD = 1.7V, VOUT = 0V, Sourcing
0.3
0.2
0.64
VDD = 5V, VOUT = 1.7V, Sinking
0.9
0.5
2.4
VDD = 5V, VOUT = 0V, Sourcing
0.4
0.1
1.46
Total Harmonic Distortion
CIN
Input Capacitance
ZIN
Input Impedance
AV
Gain
Units
dBV
LMV1032-06
RO
THD
Max (2)
Ω
100
f = 1 kHz
VIN = 18 mVPP
mV
MΩ
LMV1032-06
5.5
4.5
6.2
6.7
7.7
LMV1032-15
14.8
14
15.4
16
17
LMV1032-25
24.8
24
25.5
26.2
27
dB
Connection Diagram
Large Dome 4-Bump DSBGA
A2
OUTPUT
X
A1
GND
B2
VCC
B1
INPUT
Figure 1. Top View
•
•
Note:
Pin numbers are referenced to package marking text orientation.
The actual physical placement of the package marking will vary slightly from part to part. The package will
designate the date code and will vary considerably. Package marking does not correlate to device type in any
way.
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LMV1032
SNAS233G – DECEMBER 2003 – REVISED MAY 2013
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Typical Performance Characteristics
Unless otherwise specified, VS = 1.7V, single supply, TA = 25°C
Supply Current vs. Supply Voltage (LMV1032-06)
Supply Current vs. Supply Voltage (LMV1032-15)
75
70
70
SUPPLY CURRENT (PA)
SUPPLY CURRENT (PA)
85°C
65
25°C
60
-40°C
55
50
1.5
2
2.5
3
3.5
4
4.5
5
60
25°C
55
-40°C
50
45
1.5
5.5
85°C
65
2
2.5
SUPPLY VOLTAGE (V)
3
3.5
4
4.5
5
5.5
SUPPLY VOLTAGE (V)
Figure 2.
Figure 3. '
Supply Current vs. Supply Voltage (LMV1032-25)
Closed Loop Gain and Phase vs. Frequency (LMV1032-06)
10.00
70
180
GAIN
5.00
135
0.00
90
-5.00
45
25°C
60
0
-10.00
PHASE
-15.00
-45
-20.00
-90
-25.00
-135
-40°C
55
50
1.5
-180
-30.00
2
2.5
3
3.5
4
4.5
5
10
5.5
1k
100
10k
100k
1M
FREQUENCY (Hz)
SUPPLY VOLTAGE (V)
Figure 4.
Figure 5.
Closed Loop Gain and Phase vs. Frequency (LMV1032-15)
20
Closed Loop Gain and Phase vs. Frequency (LMV1032-25)
30
450
450
GAIN
GAIN
25
400
400
10
20
350
250
-5
GAIN (dB)
300
0
15
PHASE (°)
PHASE
5
350
PHASE
10
300
5
0
PHASE (°)
15
GAIN (dB)
PHASE (°)
65
GAIN (dB)
SUPPLY CURRENT (PA)
85°C
250
-5
200
-10
150
-15
10
100
1k
10k
100k
1M
200
-10
-15
150
10
1k
10k
100k
1M
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 6.
4
100
Figure 7.
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Typical Performance Characteristics (continued)
Unless otherwise specified, VS = 1.7V, single supply, TA = 25°C
Power Supply Rejection Ratio vs. Frequency (LMV1032-15)
120
120
100
100
80
80
PSRR (dB)
PSRR (dB)
Power Supply Rejection Ratio vs. Frequency (LMV1032-06)
60
60
40
40
20
20
0
10
0
100
1k
10k
100k
10
FREQUENCY (Hz)
100
1k
10k
100k
FREQUENCY (Hz)
Figure 8. \
Figure 9.
Power Supply Rejection Ratio vs. Frequency (LMV1032-25)
Total Harmonic Distortion vs. Frequency (LMV1032-06)
120
0.7
100
0.6
VIN = 18 mVPP
0.5
THD+N (%)
PSRR (dB)
80
60
40
0.4
0.3
0.2
20
0.1
0.0
0
10
100
1k
10k
10
100k
100
1k
10k
100k
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 10.
Figure 11.
Total Harmonic Distortion vs. Frequency (LMV1032-15)
Total Harmonic Distortion vs. Frequency (LMV1032-25)
0.7
0.6
VIN = 18 mVPP
VIN = 18 mVPP
0.6
0.5
0.4
THD+N (%)
THD + N (%)
0.5
0.4
0.3
0.3
0.2
0.2
0.1
0.1
0.0
0.0
10
100
1k
10k
100k
FREQUENCY (Hz)
10
100
1k
10k
100k
FREQUENCY (Hz)
Figure 12.
Figure 13.
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SNAS233G – DECEMBER 2003 – REVISED MAY 2013
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Typical Performance Characteristics (continued)
Unless otherwise specified, VS = 1.7V, single supply, TA = 25°C
Total Harmonic Distortion vs. Input Voltage (LMV1032-15)
1.6
1.6
1.4
1.4
1.2
1.2
1.0
1.0
THD+N (%)
THD+N (%)
Total Harmonic Distortion vs.Input Voltage (LMV1032-06)
0.8
0.6
0.4
0.8
0.6
0.4
0.2
0.2
f = 1 kHz
f = 1 kHz
0.0
0.0
0
50
100 150 200 250 300 350 400
0
50
INPUT VOLTAGE (mVPP)
100
150
200
INPUT VOLTAGE (mVPP)
Figure 14.
Figure 15.
Total Harmonic Distortion vs. Input Voltage (LMV1032-25)
Output Voltage Noise vs. Frequency (LMV1032-06)
1.6
-100
1.4
-105
-110
NOISE (dBV/ Hz)
THD+N (%)
1.2
1.0
0.8
0.6
0.4
-115
-120
-125
-130
-135
-140
0.2
-145
f = 1 kHz
-150
0.0
0
20
40
60
10
80
100
10k
100k
Figure 17.
Output Voltage Noise vs. Frequency (LMV1032-15)
Output Voltage Noise vs. Frequency (LMV1032-25)
-80
-80
-90
-90
-100
-100
NOISE (dBV/ Hz)
NOISE (dBV/ Hz)
Figure 16.
-110
-120
-130
-140
-110
-120
-130
-140
-150
-150
10
100
1k
10k
100k
FREQUENCY (Hz)
10
100
1k
10k
100k
FREQUENCY (Hz)
Figure 18.
6
1k
FREQUENCY (Hz)
INPUT VOLTAGE (mVPP)
Figure 19.
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APPLICATION SECTION
LOW CURRENT
The LMV1032 has a low supply current which allows for a longer battery life. The low supply current of 60µA
makes this amplifier optimal for microphone applications which need to be always on.
BUILT-IN GAIN
The LMV1032 is offered in the space saving small DSBGA package which fits perfectly into the metal can of a
microphone. This allows the LMV1032 to be placed on the PCB inside the microphone.
The bottom side of the PCB has the pins that connect the supply voltage to the amplifier and make the output
available. The input of the amplifier is connected to the microphone via the PCB.
DIAPHRAGM
xx
xxx
x
x
ELECTRET
AIRGAP
BACKPLATE
CONNECTOR
x
x
IC
x
LMV1032
VCC
x
VOUT
GND
Figure 20. Built-in Gain
A-WEIGHTED FILTER
The human ear has a frequency range from 20 Hz to about 20 kHz. Within this range the sensitivity of the human
ear is not equal for each frequency. To approach the hearing response weighting filters are introduced. One of
those filters is the A-weighted filter.
The A-weighted filter is usually used in signal-to-noise ratio measurements, where sound is compared to device
noise. It improves the correlation of the measured data to the signal-to-noise ratio perceived by the human ear.
10
0
-10
dBV
-20
-30
-40
-50
-60
-70
10
100
1k
10k
100k
FREQUENCY (Hz)
Figure 21. A-Weighted Filter
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LMV1032
SNAS233G – DECEMBER 2003 – REVISED MAY 2013
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MEASURING NOISE AND SNR
The overall noise of the LMV1032 is measured within the frequency band from 10 Hz to 22 kHz using an Aweighted filter. The input of the LMV1032 is connected to ground with a 5 pF capacitor.
A-WEIGHTED FILTER
5pF
Figure 22. Noise Measurement Setup
The signal-to-noise ratio (SNR) is measured with a 1 kHz input signal of 18 mVPP using an A-weighted filter. This
represents a sound pressure level of 94 dB SPL. No input capacitor is connected.
SOUND PRESSURE LEVEL
The volume of sound applied to a microphone is usually stated as the pressure level with respect to the threshold
of hearing of the human ear. The sound pressure level (SPL) in decibels is defined by:
Sound pressure level (dB) = 20 log Pm/PO
Where,
Pm is the measured sound pressure
PO is the threshold of hearing (20μPa)
In order to be able to calculate the resulting output voltage of the microphone for a given SPL, the sound
pressure in dB SPL needs to be converted to the absolute sound pressure in dBPa. This is the sound pressure
level in decibels which is referred to as 1 Pascal (Pa).
The conversion is given by:
dBPa = dB SPL + 20*log 20 μPa
dBPa = dB SPL - 94 dB
Translation from absolute sound pressure level to a voltage is specified by the sensitivity of the microphone. A
conventional microphone has a sensitivity of −44 dBV/Pa.
ABSOLUTE
SOUND
PRESSURE
[dBPa]
-94dB
SENSITIVITY
[dBV/Pa]
SOUND
PRESSURE
[dB SPL]
VOLTAGE
[dBV]
Figure 23. dB SPL to dBV Conversion
8
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Example: Busy traffic is 70 dB SPL
VOUT = 70 −94 −44 = −68 dBV
This is equivalent to 1.13 mVPP
Since the LMV1032-15 has a gain of 5.6 (15 dB) over the JFET, the output voltage of the microphone is 6.35
mVPP. By replacing the JFET with the LMV1032-15, the sensitivity of the microphone is −29 dBV/Pa (−44 + 15).
LOW FREQUENCY CUT OFF FILTER
To reduce noise on the output of the microphone a low cut filter has been implemented in the LMV1032. This
filter reduces the effect of wind and handling noise.
It's also helpful to reduce the proximity effect in directional microphones. This effect occurs when the sound
source is very close to the microphone. The lower frequencies are amplified which gives a bass sound. This
amplification can cause an overload, which results in a distortion of the signal.
20
450
GAIN
15
400
350
PHASE
5
300
0
PHASE (°)
GAIN (dB)
10
250
-5
200
-10
150
-15
10
1k
100
10k
100k
1M
FREQUENCY (Hz)
Figure 24. Gain vs. Frequency
The LMV1032 is optimized to be used in audio band applications. The LMV1032 provides a flat gain response
within the audio band and offers linearity and excellent temperature stability.
ADVANTAGE OF THREE PINS
The LMV1032 ECM solution has three pins instead of the two pins provided in the case of a JFET solution. The
third pin provides the advantage of a low supply current, high PSRR and eliminates the need for additional
components.
Noise pick-up by a microphone in a cell phone is a well-known problem. A conventional JFET circuit is sensitive
for noise pick-up because of its high output impedance. The output impedance is usually around 2.2 kΩ. By
providing separate output and supply pins a much lower output impedance is achieved and therefore is less
sensitive to noise pick-up.
RF noise is among other caused by non-linear behavior. The non-linear behavior of the amplifier at high
frequencies, well above the usable bandwidth of the device, causes AM demodulation of high frequency signals.
The AM modulation contained in such signals folds back into the audio band, thereby disturbing the intended
microphone signal. The GSM signal of a cell phone is such an AM-modulated signal. The modulation frequency
of 216 Hz and its harmonics can be observed in the audio band. This type of noise is called bumblebee noise.
EXTERNAL PRE-AMPLIFIER APPLICATION
The LMV1032 can also be used outside of an ECM as a space saving external pre-amplifier. In this application,
the LMV1032 follows a phantom biased JFET microphone in the circuit. This is shown in Figure 25. The input of
the LMV1032 is connected to the microphone via the 2.2 µF capacitor. The advantage of this circuit over one
with only a JFET microphone are the additional gain and the high pass filter supplied by the LMV1032. The high
pass filter makes the output signal more robust and less sensitive to low frequency disturbances. In this
configuration the LMV1032 should be placed as close as possible to the microphone.
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LMV1032
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VDD
VDD
2.2 k:
VDD
VIN
2.2 PF
JFET
Microphone
VOUT
VOUT
GND
LMV1032
GND
Figure 25. LMV1032 as External Pre-Amplifier
10
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REVISION HISTORY
Changes from Revision F (May 2013) to Revision G
•
Page
Changed layout of National Data Sheet to TI format .......................................................................................................... 10
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PACKAGE OPTION ADDENDUM
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10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
(3)
Device Marking
(4/5)
(6)
LMV1032UP-06/NOPB
ACTIVE
DSBGA
YPC
4
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
LMV1032UP-15/NOPB
ACTIVE
DSBGA
YPC
4
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
LMV1032UP-25/NOPB
ACTIVE
DSBGA
YPC
4
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
LMV1032UPX-06/NOPB
ACTIVE
DSBGA
YPC
4
3000
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
LMV1032UR-15/NOPB
ACTIVE
DSBGA
YPD
4
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
LMV1032UR-25/NOPB
ACTIVE
DSBGA
YPD
4
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
LMV1032URX-15/NOPB
ACTIVE
DSBGA
YPD
4
3000
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
LMV1032URX-25/NOPB
ACTIVE
DSBGA
YPD
4
3000
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
-40 to 85
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of