Telit Wireless Solutions GE863-QUAD, GE863-PY manual Buffered Unbalanced Single Ended Microphone

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GE863-QUAD

GE863-PY

1vv0300715 Rev. 1 - 19/09/06

7.5.2 Buffered Unbalanced (Single Ended) Microphone .

2,7nF

6,8nF

GE863

Mic+

To

GE863

GE863

Mic-

The above schematic can be used for a single ended (buffered unbalanced) microphone ; the required biasing circuitry is not included. Note also that the capacitor C3 is not needed .

The gains of the two amplifiers are given by the formulas :

	Gain(not inverting buffer) = 1 +	R719	Gain(inverting buffer) =	R711
		R720		R708

Assigning half of overall gain to each amplifier, you will obtain the requested gain because of doubling the microphone signal path; in fact by the use of two amplifiers (the upper as “inverting” and the lower as “not inverting”configuration ) we obtain an additional +6dB gain (2 times) .

Remember : the “not inverting “ amplifier section gain shall not be less than 1 .

Like for the balanced buffered microphone , the amplifier overall gain can be modify changing the value of resistor R719/R720 and R711 and as a consequence the capacitors C726 and C727. It is advisable to change R708 only if you have difficulty to find a commercial value for R711 ; in this case change R708 as little as possible .

The -3dB bandwidth is given by the approximated formula (considering C725 >> C726):

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Contents GE863-QUAD GE863-PY Hardware User Guide Contents 10.2 10.110.3 10.413.2 12.113.1 This document is relating to the following products Overview PIN-OUT GE863 module connectionsPin Signal Function Internal Type Pull up Pin Signal Function Internal Type Pins Layout Turning on the GE863-QUAD/PY Hardware CommandsTurning off of the device can be done in two ways Turning OFF the GE863-QUAD/PYHardware shutdown Hardware Unconditional RebootGE863-QUAD GE863-QUAD/PY power requirements are Power Supply1Power Supply Requirements Electrical design Guidelines 2General Design RulesAn example of linear regulator with 5V input is 1.2 + 12V input Source Power Supply Design GuidelinesAn example of switching regulator with 12V input is Battery Source Power Supply Design GuidelinesBattery Charge control Circuitry Design Guidelines Thermal Design Guidelines Power Supply PCB layout Guidelines GSM Antenna Requirements AntennaGSM Antenna PCB line Guidelines GSM Antenna installation GuidelinesSerial Ports Level Min Max Absolute Maximum Ratings -Not Functional Parameter Min MaxNumber Pad Number Signals in the Uart connector on the EVK are17-28-36 Ground 45-48-50-56 Clear to Send Output from the GE863-QUAD/PY that3RS232 level translation It is available on the following pins2MODEM Serial Port 2 Python Debug An example of level translation circuitry of this kind is 5V Uart level translation GE863-QUAD Audio Section Overview GM863-GPS Echo canceller type Handset Microphone Paths Characteristic and RequirementsEcho canceller type Car kit hands-free + 20dBYou can set GA= +20dB to use standard resistor values That meansTIP environment consideration Other considerations General Design RulesBalanced Microphone Biasing Microphone BiasingUnbalanced Microphone Biasing GE863-QUAD Sample circuit can be Microphone BufferingBuffered Balanced Mic Buffer gain is given by the formula Gain = RR604605 = RR607606Buffered Unbalanced Single Ended Microphone Buffer bandwidth at -3dB shall be 4KHz Freq . = 2π * R719* C726 2π * R711* C727GE863-QUAD Short description Output Lines SpeakerSW volume level step Number of SW volume steps Output Lines CharacteristicsNoise Filtering Handset Earphone Design An example of internal Ear amplifier could be Hands-Free Earphone Low Power DesignCar Kit Speakerphone Design Short Description Evaluation Kit for Telit Modules EVK2@ 350mW 2 EVK2 Audio Lines CharacteristicsESD Data IntegritySIM Supply SchematicLayout General Purpose I/O Using a Gpio Pad as InputUsing a Gpio Pad as Output Using the Buzzer Output GPIO7 10.3Using the Alarm Output GPIO611.1DAC Converter DAC and ADC sectionDescription Min Max UnitsCommand is AT#DAC=enable,value An AT command is available to use the DAC functionEnabling DAC Low Pass Filter Example11.2ADC Converter Using ADC ConverterInput Voltage range AD conversion Bits Resolution 12.1Transchip Camera CameraType Sensitivity LuxCamera Interface Connectors Camera Physical Detail & Connector Camera Socket Connector Camera Board Module Main Block Diagram for supported cameras Schematic Diagrams for supported camera Taking an reading a photo Camera setting shown here are the defaults onesExample usage script for camera 13.1General 13.2Module Finishing & DimensionsMounting the GE863-QUAD / PY on the Application Board Lead-free Alloy Surface finishing Ni/Au for all test padsRecommended foot print for the application PCB pad Design Debug of the GE863 in ProductionStencil Solder paste Following is the recommended solder reflow profile 13.2.6 GE863-QUAD / PY Solder ReflowGE863-QUAD Section A-A Packing SystemModules orientation on tray Moisture Sensibility Conformity Assessment Issues Safety Recommandations Revision Date Changes Document Change Log21/02/06 19/09/06