NSC LMV1024URX Pdm output with pre-amplifier for electret microphone Datasheet

July 20, 2009
LMV1024/LMV1026 (Stereo)
PDM Output with Pre-Amplifier for Electret Microphones
General Description
Features
National’s LMV1024 and LMV1026 stereo amplifiers are solutions for the new generation of voice enrichment capabilities. National has integrated sigma delta modulation and
analog cores to improve the voice quality and the performance and to support designer’s choices.
Each 20 kHz preamplifier drives a Pulse Density Modulated
(PDM) signal at an over sampled 60 bit stream, offering versatility. These solutions provide immediate conversion to high
performance audio spectrum, thus completing a high quality
audio system. The LMV1024 and LMV1026 operate from
1.6V to 3V.
National’s new adjustable clock frequency technology is designed for stereo, performance and ease of use. The stereo
function is either a rising or falling edge clock command. The
high drive, robust PDM signal directly from an ECM (Electret
Condenser Microphone), upgrades existing lower quality,
low-level signal constraints.
These advanced mixed signal preamplifiers cleanly, accurately and creatively eliminate older, poorer quality systems,
which restricted performance and versatility. The 4-wire PDM
signaling reduces RF noise and simplifies layout. Using
National’s PDM solutions is the choice for higher quality mono
or stereo and multi-array applications.
National’s 518uA circuits deliver stereo portability with audio
quality bandwidth. These solutions enable rapid system evaluation and enhance consumer satisfaction. National provides
the LMV1024 and LMV1026 in 6-bump micro SMD packages
with 1 kg adhesion properties.
(Typical VDD = 1.8V, CLOCK = 1.2 MHz, fINPUT = 1 kHz,
VINPUT = 18 mVPP, unless otherwise specified)
■ Enhanced high-performance, full PDM output from the element
■ Stereo chipset and array routing
59 dB
■ SNR A-weighted
−89 dBFS
■ Digital A-weighted noise floor
518 µA
■ Supply current
400 kHz to 2.4 MHz
■ Clock frequency
0.03%
■ Total harmonic distortion
100 dB
■ Power supply rejection ratio
■ Adhesion technology >1 kg
■ Highly integrated stereo or mono signaling
■ Maximized system performance
■ Reduced components and layout
■ RF (buzz noise) managed with 4 wire signaling
■ Thinnest 0.35 mm micro SMD packaging
Applications
■
■
■
■
■
■
Digital output audio subsystems and stereo arrays
Electret condenser microphones with all digital output
Portable communications and small form factor
Digital audio computing or voice security
Automotive or array systems
Headphone and Headset accessories
Typical Application
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For a stereo application, see STEREO OPERATION in the Application Section.
© 2009 National Semiconductor Corporation
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LMV1024/LMV1026 PDM Output with Pre-Amplifier for Electret Microphones
OBSOLETE
LMV1024/LMV1026
Junction Temperature (Note 6)
Mounting Temperature
Infrared or Convection (20 sec.)
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
ESD Tolerance (Note 2)
Human Body Model
Machine Model
Supply Voltage
VDD - GND
Storage Temperature Range
Operating Ratings
150°C max
235°C
(Note 1)
Supply Voltage
Input Clock Frequency
Duty Cycle
Operating Temperature Range
2500V
250V
3.3V
−65°C to 150°C
1.6V to 3.0V
400 kHz to 2.4 MHz
40% to 60%
−40°C to 85°C
1.8V Electrical Characteristics
(Note 3)
Unless otherwise specified, all limits are guaranteed for TJ = 25°C, VDD = 1.8V, VIN = 18 mVPP, fCLK = 1.2 MHz, Duty Cycle = 50%
and 100 nF capacitor between VREF and GND. Boldface limits apply at the temperature extremes.
Symbol
Parameter
Conditions
Min
(Note 4)
Typ
(Note 5)
SNR
Signal to Noise Ratio
fIN = 1 kHz, A-Weighted
59
eN
Digital Noise Floor (Integrated)
f = 20 Hz to 10 kHz, A-Weighted, 4.7 pF
Capacitor Connected from Input to
GND to Simulate ECM, No Signal
−89
Max
(Note 4)
Units
dB
dBFS(A)
THD
Total Harmonic Distortion
fIN = 1 kHz, VIN = 18 mVPP
0.03
IDD
Supply Current
VIN = GND, CLK = ON, High Impedance
Load (Note 7)
518
VIN = GND, CLK = OFF
503
%
µA
600
VIL
CLOCK Input Logic Low Level
VIH
CLOCK Input Logic High Level
VOL
DATA Output Logic Low Level
VOH
DATA Output Logic High Level
VIN
Max Input Signal
fIN = 1 kHz, THD < 1%
243
mVPP
VOUT
Max Output Signal
fIN = 1 kHz, THD < 1%
−6.8
dBFS
PSRR
Power Supply Rejection Ratio
VIN = GND, Test Signal on VDD = 217
Hz, 100 mVPP
100
dB
tA
Time from CLOCK Transition to
DATA Becoming High Impedance
(See also Figure 10, Application
Section)
LMV1024: On Rising Edge of the
CLOCK
65
ns
Time from CLOCK Transition to
DATA Becoming Valid (See also
Figure 10, Application Section)
LMV1024: On Falling Edge of the
CLOCK
90
ns
2
pF
1000
MΩ
tB
CIN
Input Capacitance
RIN
Input Impedance
0.3
1.5
V
0.1
1.7
LMV1026: On Falling Edge of the
CLOCK
LMV1026: On Rising Edge of the
CLOCK
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V
V
V
(Note 3)
Unless otherwise specified, all limits are guaranteed for TJ = 25°C, VDD = 2.7V, VIN = 18 mVPP, fCLK = 1.2 MHz, Duty Cycle = 50%
and 100 nF capacitor between VREF and GND. Boldface limits apply at the temperature extremes.
Symbol
Parameter
Conditions
Min
(Note 4)
Typ
(Note 5)
Max
(Note 4)
Units
SNR
Signal to Noise Ratio
fIN = 1 kHz, A-Weighted
59
dB
en
Digital Noise Floor (Integrated)
f = 20 Hz to 10 kHz, A-Weighted, 4.7 pF
Capacitor Connected from Input to
GND to Simulate ECM, No Signal
−89
dBFS(A)
THD
Total Harmonic Distortion
fIN = 1 kHz, VIN = 18 mVPP
0.03
%
IDD
Supply Current
VIN = GND, CLK = ON, High Impedance
Load (Note 7)
535
μA
VIN = GND, CLK = OFF
519
650
VLOW
CLOCK Logic Low Level
VHIGH
CLOCK Logic High Level
VOL
DATA Output Logic Low Level
VOH
DATA Output Logic High Level
VIN
Max Input Signal
fIN = 1 kHz, THD < 1%
249
mVPP
VOUT
Max Output Signal
fIN = 1 kHz, THD < 1%
−6.6
dBFS
PSRR
Power Supply Rejection Ratio
VIN = GND, Test Signal on VDD = 217
Hz, 100 mVPP
100
dB
tA
Time from CLOCK Transition to
DATA Becoming High Impedance
(See also Figure 10, Application
Section)
LMV1024: On Rising Edge of the
CLOCK
65
ns
Time from CLOCK Transition to
DATA Becoming Valid (See also
Figure 10, Application Section)
LMV1024: On Falling Edge of the
CLOCK
90
ns
2
pF
1000
MΩ
tB
CIN
Input Capacitance
RIN
Input Impedance
V
0.3
V
2.4
V
0.1
V
2.6
LMV1026: On Falling Edge of the
CLOCK
LMV1026: On Rising Edge of the
CLOCK
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended to be functional, but specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics.
Note 2: The Human Body Model (HBM) is 1.5 kΩ in series with 100 pF. The Machine Model is 0Ω in series with 200 pF.
Note 3: Electrical table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very limited self-heating
of the device such that TJ = TA. No guarantee of parametric performance is indicated in the electrical tables under conditions of internal self-heating where TJ >
TA.
Note 4: All limits are guaranteed by design or statistical analysis.
Note 5: Typical values represent the most likely parametric norm.
Note 6: The maximum power dissipation is a function of TJ(MAX) , θJA and TA. The maximum allowable power dissipation at any ambient temperature is
PD = (TJ(MAX) - TA)/θJA. All numbers apply for packages soldered directly into a PC board.
Note 7: The Supply Current depends on the applied Clock Frequency and the load on the DATA output.
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LMV1024/LMV1026
2.7V Electrical Characteristics
LMV1024/LMV1026
Connection Diagram
Large Dome 6-Bump Ultra Thin micro SMD
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Top View
Pin Descriptions
Pin
Name
Description
A2
VDD
Positive supply voltage
C1
GND
Ground
Input
C2
Input
The microphone is connected to this input pin.
Reference
B1
VREF
A capacitor of 100 nF is connected between VREF and ground. This capacitor is used to filter
the internal converter reference voltage.
Clock Input
A1
Clock
The user adjustable clock frequency ranges from 400 kHz to 2.4 MHz.
Data Output
B2
Data
Over sampled bitstream output. Data is valid if clock is LOW (LMV1024). The data of the
LMV1026 data is valid when clock is HIGH. When the data is not valid the data output is
Hi-Z. For exact specifications see application section.
Power Supply
Ordering Information
Package
Part Number
Package Marking
LMV1024UR
6-Bump Ultra Thin micro SMD
lead free only
IE
LMV1024URX
LMV1026UR
IF
LMV1026URX
Transport Media
3k Units Tape and Reel
250 Units Tape and Reel
3k Units Tape and Reel
Block Diagram
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NSC Drawing
250 Units Tape and Reel
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URA06GGA
Unless otherwise specified, measurements are performed on an
LMV1024 with VDD = 1.8V, Clock Duty Cycle = 50% and a 100 nF capacitor is placed between VREF and GND, TJ = 25°C.
Supply Current vs. Supply Voltage
@ CLOCK = 1.2 MHz
Supply Current vs. Supply Voltage
@ CLOCK = 2.4 MHz
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Supply Current vs. Supply Voltage
CLOCK = OFF
SNR, SINAD and -THD vs. Input Amplitude
@ CLOCK = 408 kHz, 3.4 kHz Audio BW
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SNR, SINAD and -THD vs. Input Amplitude
@ CLOCK = 960 kHz, 8 kHz Audio BW
SNR, SINAD and -THD vs. Input Amplitude
@ CLOCK = 1.2 MHz, 10 kHz Audio BW
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LMV1024/LMV1026
Typical Performance Characteristics
LMV1024/LMV1026
SNR, SINAD and -THD vs. Input Amplitude
@ CLOCK = 1.92 MHz, 16 kHz Audio BW
SNR, SINAD and -THD vs. Input Amplitude
@ CLOCK = 2.4 MHz, 20 kHz Audio BW
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SNR, SINAD and -THD vs. Output
@ CLOCK = 408 kHz, 3.4 kHz Audio BW
SNR, SINAD and -THD vs. Output
@ CLOCK = 960 kHz, 8 kHz Audio BW
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SNR, SINAD and -THD vs. Output
@ CLOCK = 1.2 MHz, 10 kHz Audio BW
SNR, SINAD and -THD vs. Output
@ CLOCK = 1.92 MHz, 16 kHz Audio BW
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SINAD vs. Frequency
@ CLOCK = 408 kHz, 3.4 kHz Audio BW
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SINAD vs. Frequency
@ CLOCK = 960 kHz, 8 kHz Audio BW
SINAD vs. Frequency
@ CLOCK = 1.2 MHz, 10 kHz Audio BW
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SINAD vs. Frequency
@ CLOCK = 1.92 MHz, 16 kHz Audio BW
SINAD vs. Frequency
@ CLOCK = 2.4 MHz, 20 kHz Audio BW
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LMV1024/LMV1026
SNR, SINAD and -THD vs. Output
@ CLOCK = 2.4 MHz, 20 kHz Audio BW
LMV1024/LMV1026
Noise vs. Frequency
@ CLOCK = 408 kHz, 3.4 kHz Audio BW
Noise vs. Frequency
@ CLOCK = 960 kHz, 8 kHz Audio BW
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Noise vs. Frequency
@ CLOCK = 1.2 MHz, 10 kHz Audio BW
Noise vs. Frequency
@ CLOCK = 1.92 MHz, 16 kHz Audio BW
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Noise vs. Frequency
@ CLOCK = 2.4 MHz, 20 kHz Audio BW
PSRR vs. Frequency
@ CLOCK = 1.2 MHz
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Output vs. Input Amplitude
@ CLOCK = 408 kHz, 3.4 kHz Audio BW
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Output vs. Input Amplitude
@ CLOCK = 960 kHz, 8 kHz Audio BW
Output vs. Input Amplitude
@ CLOCK = 1.2 MHz, 10 kHz Audio BW
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Output vs. Input Amplitude
@ CLOCK = 1.92 MHz, 16 kHz Audio BW
Output vs. Input Amplitude
@ CLOCK = 2.4 MHz, 20 kHz Audio BW
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LMV1024/LMV1026
PSRR vs. Frequency
@ CLOCK = 2.4 MHz
LMV1024/LMV1026
Output vs. Frequency
@ CLOCK = 408 kHz, 3.4 kHz Audio BW
Output vs. Frequency
@ CLOCK = 960 kHz, 8 kHz Audio BW
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Output vs. Frequency
@ CLOCK = 1.2 MHz, 10 kHz Audio BW
Output vs. Frequency
@ CLOCK = 1.92 MHz, 16 kHz Audio BW
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Output vs. Frequency
@ CLOCK = 2.4 MHz, 20 kHz Audio BW
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The LMV1024/LMV1026 consist of a pre-amplifier and sigma
delta converter for placement inside an electret condenser
microphone (ECM). The output of the LMV1024/LMV1026 is
a robust digital serial bit stream eliminating the sensitive lowlevel analog signals of conventional JFET microphones. This
application section describes, among others, a typical application, a sensitivity comparison between different ECM types,
stereo operation and layout recommendations on the ECM
PCBs.
20133424
FIGURE 1. Typical Application
BUILT-IN PRE-AMPLIFIER / ADC
The LMV1024/LMV1026 are offered in a space saving small
6-bump micro SMD package in order to fit inside small ECM
canisters. The LMV1024 or LMV1026 IC is placed on the
PCB. This PCB forms the bottom of the microphone, which is
placed in the cell phone.
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FIGURE 3. Cross section of a Microphone
FIGURE 2. Built-in Pre-Amplifier / ADC
Figure 3 depicts a cross section of a microphone with the IC
inside the ECM canister. The PCB of the microphone has 4
pads that connects VDD, Ground, DATA and the CLOCK.
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LMV1024/LMV1026
TYPICAL APPLICATION
Figure 1 depicts a typical application, where the LMV1024 or
LMV1026 is built inside the ECM canister. This ECM can be
directly connected to a DSP in a digital audio system, like a
baseband chip in a cell phone. Connecting is easy because
of the digital LMV1024/LMV1026 interface. A digital filter in
the DSP or Baseband decimates the audio signal.
Application Section
LMV1024/LMV1026
to conventional microphones. This section compares the various microphone types and their sensitivity. Examples are
given to calculate the resulting output for a given sound pressure.
A-WEIGHTED FILTER
The human ear has a frequency range from about 20 Hz to
20 kHz. Within this range the sensitivity of the human ear is
not equal for each frequency. In order to approach a natural
hearing response, weighting filters are introduced. One of
these filters is the A-weighted filter. The A-weighted filter is
commonly used in signal-to-noise ratio measurements, where
sound is compared to device noise. The filter improves the
correlation of the measured data to the signal-to-noise ratio
perceived by the human ear.
Sound Pressure Level
The volume of sound applied to a microphone is usually stated as a sound pressure in dB SPL. This unity of dB SPL refers
to the threshold of hearing of the human ear. The sound pressure in decibels is defined by:
SPL = 20 log (PM/PO)
Where,SPL is the Sound Pressure in dB SPLPM is the measured absolute sound pressure in PaPO is the threshold of
hearing (20 µPa)
In order to calculate the resulting output voltage of the electret
element for a given sound pressure in dB SPL, the absolute
sound pressure PM must be known. This is the absolute sound
pressure in decibels referred to 1 Pa instead of 20 µPa.
The absolute sound pressure PM in dBPa is given by:PM =
SPL (dB SPL) + PO (dBPa)PM = SPL + 20*log 20 µPaPM =
SPL - 94 dB
JFET Microphone
Translation from the absolute sound pressure level to a voltage can be done when the electrets sensitivity is known. A
typical electret element has a sensitivity of −44 dB(V/Pa). This
is also the typical sensitivity number for the JFET microphone,
since a JFET usually has a gain of about 1x (0 dB). A block
diagram of a microphone with a JFET is given in Figure 5.
Example: Busy traffic has a Sound Pressure of 70 dB SPL.
Microphone Output = SPL + C + S
Where,SPL is the Sound Pressure in dB SPLC is the dB SPL
to dBPa conversion (−94 dB)S is the Sensitivity in dB(V/Pa)
Microphone Output = 70 – 94 – 44 = −68 dBVThis is equivalent to 1.13 mVPP.
The analog output signal is so low that it can easily be distorted by interference from outside the microphone. Additional gain is desirable to make the signal less sensitive to
interference.
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FIGURE 4. A-weighted Filter
SENSITIVITY
Sensitivity is a measure for the transfer from the applied
acoustic signal to the output of the microphone. Conventional
JFET microphones and microphones with built-in gain have
a sensitivity that is expressed in dB(V/Pa), where 0dB = 1V/
Pa. A certain pressure on the electret of the microphone gives
a certain voltage at the output of the microphone. Since the
LMV1024 microphone has a digital output, the sensitivity will
be stated in dB(Full Scale/Pascal) or dB(FS/Pa) as opposed
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LMV1024/LMV1026
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FIGURE 5. Microphone Sensitivity
band chip significantly. To minimize interference ultimately,
an Analog-to-Digital converter is integrated in both the
LMV1024/LMV1026, realizing a digital interface between the
microphone and the baseband.
Microphone with Additional Gain
When gain is added to the electret element, the analog signal
becomes larger and therefore more robust. This can be accomplished by using a pre-amplifier with a higher gain then
the JFET. The sensitivity of the microphone consists of the
sensitivity of the electret plus the gain of the pre-amplifier.
When choosing National Semiconductor's LMV1015-15 for
instance, a gain of 15 dB is added by the pre-amplifier. This
results in a sensitivity of −29 dB(V/Pa) with a typical electret
element of −44 dB(V/Pa). National Semiconductor has a wide
range of pre-amplifiers with different gain factors, which can
be used to replace the JFET inside the microphone canister.
Please visit www.national.com for more information on the
LMV1015 and LMV1032 pre-amplifier series. A block diagram
with the LMV1015 pre-amplifier inside an ECM is given in
Figure 5.
When taking the same example of busy traffic (70 dB SPL),
the output voltage of the microphone with the LMV1015 is:
Microphone Output = SP + C + S
Where,SP is the Sound Pressure in dB SPLC is the dB SPL
to dBPa conversion (−94 dB)S is the Sensitivity in dB(V/Pa)
Microphone output = 70 - 94 - 29 = −53 dBV. This is equivalent
to 6.33 mVPP.
The pre-amplifier with additional gain reduces the impact of
noise on the wiring / traces from the microphone to the base-
Digital Microphone
By integrating the Analog-to-Digital converter (ADC) in the
LMV1024/LMV1026 all analog signals are kept within the
“shielded” microphone canister. The output is a digital interface that is robust and insensitive to interference and noise
from outside the canister. The output is expressed in dBFS
and therefore the sensitivity is also stated in dB(FS/Pa) instead of dB(V/Pa). To calculate the digital output (Data) in
dBFS the following equation can be written for the LMV1024/
LMV1026:
(1)
Where,
PREF is the reference power, which is defined as the maximum
allowed input power (Full Scale). PINPUT is the applied power
on the input pin and “A” is the gain of the pre-amplifier in decibels.
Written into voltages, the equation is:
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LMV1024/LMV1026
Where,SP is the Sound Pressure in dB SPLC is the dB SPL
to dBPa conversion (−94 dB)S is the Sensitivity in dB(V/Pa)
Taking the example of busy traffic (70 dB SPL) again results
in the following digital output (dBFS):
Digital Output (dBFS) = SP - C + SDigital Output (dBFS) = 70
- 94 - 28.8 = −52.8 dBFS
(2)
Or in decibels:Digital Output (dBFS) = Input (dBV) - Reference (dB) + A
Where,Input = 20 Log VINPUT (VRMS)Ref = 20 Log VREF
(VRMS)A is the Gain (dB)
For the LMV1024/LMV1026 the reference voltage VREF is
1.5VP (1.06 VRMS) and the Gain A is 15.7 dB. These parameters are fixed inside the device. Knowing this, Equation 2 can
be simplified:
Digital Output (dBFS) = VINPUT (dBV) - 0.5 + 15.7Digital Output (dBFS) = VINPUT (dBV) + 15.2
The sensitivity of the digital microphone is the sensitivity of a
conventional microphone plus the input to output transfer of
the LMV1024. The sensitivity of a typical digital microphone
is therefore: −44 + 15.2 = −28.8 dB(FS/Pa).
Digital Output = SP + C + S
ANALOG-TO-DIGITAL CONVERTER
The ADC used in the LMV1024/LMV1026 is an one bit sigma
delta converter with a Pulse Density Modulated output signal
(PDM). The output of this ADC can be either High (one) or
Low (zero). Assume that the LMV1024/LMV1026 input is at
the minimum level. In that case the DATA output will produce
almost only “zeros”. When the input increases, the amount of
“ones” increases too. At mid-point, where the input is 0V, the
number of “zeros” will equal the number of “ones”. At the time
that the input approaches the maximum level, the DATA output produces a majority of “ones”. Figure 6 shows the resulting DATA output as function of the input.
20133472
FIGURE 6. DATA Output versus Input Amplitude
The high corner of the band of interest (knee) is determined
by the clock frequency divided by 2 times the OSR. The factor
of two comes from the Nyquist theorem. The over sampling
ratio (OSR) of this particular ADC is chosen at 60. This sets
the high corner of the band at the clock frequency divided by
120. For instance when a bandwidth of 10 kHz is desired, the
clock frequency needs to be 1.2 MHz or higher. Figure 7 depicts the noise shaping effect in a frequency spectrum plot,
where a 1 kHz signal is applied.
An important characteristic of the sigma delta converter is that
the noise is shifted out of the band to frequencies above the
band of interest. The band that can be used (Audio Bandwidth) relates directly the applied clock frequency. Table 1
shows the relation between the Clock Frequency and a couple of common Audio Bandwidths.
TABLE 1. Audio Bandwidth vs. Clock Frequency
cy
Audio Bandwidth
3.4 kHz
8 kHz
10 kHz
16 kHz
20 kHz
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FIGURE 7. Frequency Spectrum
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FIGURE 8. Frequency Spectrum after Filtering
FIGURE 10. Timing
STEREO OPERATION
The LMV1024 and the LMV1026 are designed to operate together in a stereo solution with two microphones. One microphone will have a LMV1024 built-in and the other will have a
LMV1026 built-in. These two microphones share the same
interface lines to minimize wiring (Figure 9).
LAYOUT CONSIDERATIONS
To obtain the best possible performance from the microphone, special care needs to be taken for the design of the
PCB. Especially the VIN trace is very sensitive as it is connected to the high impedance electret element. It is essential
to isolate and shield the VIN trace as much as possible from
the digital signal traces (DATA and CLOCK). This needs to
be done to avoid any switching noise coupling directly into the
input of the IC. An example of a PCB layout is given in Figure
11. The microphone PCB has two capacitors. One capacitor
(100 nF) is connected to the reference pin of the LMV1024/
LMV1026. The other capacitor (10 nF) is used as decoupling
for high frequencies on the supply. No capacitors should be
placed on the data output of the LMV1024/LMV1026 since it
will only load the output driver and would degrade the performance. This is opposite to the regular analog phantom biased
microphones, where capacitors are needed to improve RFI.
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FIGURE 9. Stereo Application
Both microphones produce valid data in only one half of a
clock cycle to allow the two microphones to operate on the
20133428
FIGURE 11. PCB Layout
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LMV1024/LMV1026
same I/O lines (Data and Clock). To avoid overlap between
the drivers of the microphones, one microphone always goes
into a high impedance state before the second microphone
starts driving the data-line. The LMV1024 is positive edge
triggered while the LMV1026 is negative edge triggered. The
timing between the two microphones is shown in Figure 10.
For exact timing values, please see the Electrical Characteristics table.
To eliminate the noise above the band of interest a low pass
decimation filter is implemented in the baseband chip or DSP.
The resulting frequency spectrum contains only the frequency
components left within the band of interest. Figure 8 depicts
the frequency spectrum after filtering.
LMV1024/LMV1026
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LMV1024/LMV1026
Physical Dimensions inches (millimeters) unless otherwise noted
NOTE: UNLESS OTHERWISE SPECIFIED.
1. FOR SOLDER BUMP COMPOSITION, SEE “SOLDER INFORMATION” IN THE PACKAGING SECTION OF THE NATIONAL SEMICONDUCTOR WEB PAGE
(www.national.com).
2. RECOMMEND NON-SOLDER MASK DEFINED LANDING PAD.
3. PIN A1 IS ESTABLISHED BY LOWER LEFT CORNER WITH RESPECT TO TEXT ORIENTATION.
4. XXX IN DRAWING NUMBER REPRESENTS PACKAGE SIZE VARIATION WHERE X1 IS PACKAGE WIDTH, X2 IS PACKAGE LENGTH AND X3 IS PACKAGE HEIGHT.
5. NO JEDEC REGISTRATION AS OF MARCH 2003
6-Bump Ultra Thin micro SMD
NS Package Number URA06GGA
X1 = 1.128 mm, X2 = 1.628 mm, X3 = 0.35 mm
17
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LMV1024/LMV1026 PDM Output with Pre-Amplifier for Electret Microphones
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