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| Datasheet XE1218A: Low Power single die FM receiver RFT VCCR VCCA VDD AUD VCCO RFI RFG LNA FM DEMOD Audio SW OUT OSC AFC PA EAR LOP LON XP XN VM VSS VOL XE1218A Low power single die FM receiver General Description The XE1218 is a single die, low power, FM receiver operating in the VHF band from 130MHz to 230MHz. Its highly integrated architecture allows for RF and audio functions on the same die, whilst minimizing the external components needed to build a complete application at the same time. The XE1218A enables single chip, complete audio transmission solutions, where the antenna feeds the incoming RF signal directly into the XE1218A and an amplified audio signal can be fed to an earphone directly from the XE1218A's output. Flexibility has been built into the XE1218A: various different transmission channels can be selected, the audio output can also be fed to a post processing circuit such as sound de-emphasis or an external power amplifier. The XE1218A is optimized for battery powered applications, it can be operated directly on one lithium 1.5V battery cell. Applications * * * * Wireless phone headset Local area voice paging FM broadcasting miniature receiver Toys Main features * * * * * * * * * * Tuneable from 130MHz to 230 MHz High reception sensitivity: -100dBm Integrated RF filtering Low voltage operation: down to 1.1V Low power consumption: typical 2.5mA 6 kHz audio bandwidth 40 dB audio SNR Integrated earphone audio amplifier Line out for external audio amplifier Mute function Ordering Information Part Number XE1218AS000BF Temperature range -10C to 40C Package Bare die Cool Solutions for Wireless Connectivity XEMICS SA * e-mail: info@xemics.com * web: www.xemics.com Datasheet XE1218A: Low Power single die FM receiver Table of Contents 1. Functional description 1.1General description 1.2RF front end 1.3Audio stage 2. Functional implementation 2.1 Block diagram 2.2 Operation overview 2.3 Application example 3. Electrical characteristics 3.1 Absolute maximum ratings 3.2 Recommended operating conditions and electrical specifications 4. Interconnections 4.1 Bare die pad out 4.2 Pad coordinates 4.3 XE1218A packaging 4.4 TQFP44 pin-out 5. Input - output signal description 6. Application information 6.1 Recommended crystal oscillator 6.2 Using a low impedance audio output 6.3 Using the high impedance line out OUT 6.4 Recommended antenna 3 3 3 3 4 4 4 5 5 5 5 6 6 7 7 8 9 10 10 10 10 11 2 D0204-157 Datasheet XE1218A: Low Power single die FM receiver 1. Functional description 1.1 General description The XE1218A is an integrated FM receiver including all the necessary functions to process a modulated RF signal at its input and deliver a "speech quality" audio signal at its output. The XE1218A was designed for maximum system simplicity thus it requires only 12 external components to offer antenna in, audio out functionality. The XE1218A also offers design flexibility. A direct connection to an earphone is possible through the pin EAR, this takes advantage of the internal audio power amplifier or an external audio amplifier, or an audio processing device can be connected via the OUT (line out) pin. 1.2 RF front end The FM signal received through the antenna is delivered to an integrated LNA via an external matching circuit. A low IF architecture is implemented to down-convert the incoming signal to an intermediate frequency (IF) of 25kHz. This IF signal is then filtered to remove any DC components and equalized to offer a clean digital signal to the demodulator. The FM demodulator uses digital delay line architecture to convert the signal to a pulse width modulated signal at twice the IF frequency. The XE1218A has an integrated AFC which is used for the demodulator to have its clock frequency track the IF frequency. 1.2.1 LNA The noise figure (NF) for this block is less than 6dB, for an antenna impedance in the 1 to 2 k range. Out of the 6dB, 3dB is due to the noise of the image frequency that is not rejected. The sensitivity is -100dBm (SINAD=10 dB, fdev = 3kHz). 1.2.2 Mixer, down-conversion The down-conversion is implemented as a Gilbert cell. This implementation uses low IF and does not have provisions for integrated image rejection. The incoming audio channel will be demodulated at Flo = FIN - 25kHz. This is to say that the image frequency will be located at FIN - 50kHz and will not be attenuated by the XE1218A's RF receiving circuitry. For multi-channel operation within reception range of several XE1218A receivers, it is recommended that the various carrier frequencies be spaced by at least 100kHz, better yet 200kHz. 1.2.3 DC offset cancellation, IF amplifier chain DC components are attenuated in an off-set cancellation block. An on-chip low pass filter provides attenuation greater than 65dBm measured FIF + 100kHz 1.2.4 Demodulation and AFC circuitry The demodulator converts the signal from the IF amplifier into a pulse width modulated signal at twice the IF frequency. A follow-on block generates the AFC to track the IF frequency. Proper tracking of the IF frequency is necessary for the stability of the RF link as the XE1218A operates in narrow band mode. 1.2.5 Crystal and local oscillator The local oscillator provides the XE1218A's down-converter mixer with the proper frequency: Flo. It is implemented with a crystal oscillator working on the external crystal's overtone harmonic. 1.3 Audio stage 1.3.1 Audio processing The XE1218A integrated audio processing circuitry filters the input pulse width modulated (PWM) signal from the demodulator and provides for two different output feeds. All necessary bias currents and voltages for this analog block are on-chip, including a voltage multiplier circuit. When the incoming RF signal becomes low, the signal to noise ratio at the audio output decreases, which drastically reduces the sound quality and intelligibility. For user convenience, a mute function is implemented in the audio section. When the signal to noise ratio at the output is too low (typ. 10 to 15 dB) the audio output is shut down. 3 D0204-157 Datasheet XE1218A: Low Power single die FM receiver 1.3.2 Audio output stage An integrated power amplifier (PA) allows for a direct connection to an earphone. Controlled by an external potentiometer (100k) a maximum attenuation of 10dB is achievable on the EAR output, 21.5dB with 1M. A high impedance line out (10k) is available through the pad OUT. 2. Functional implementation 2.1 Block diagram A1 VCC VCC VCC C1 L1 RFT VCCR VCCA VDD AUD VCCO C4 RFI LNA C5 L4 RFG FM DEMOD Audio SW OUT Line OUT OSC AFC PA EAR LOP LON XP XN VM VSS XE1218 VOL L3 L2 C2 Xtal C3 R1 Volume Control 2.2 Operation overview While the XE1218A is a single channel receiver, various fixed frequencies can be selected between 130MHz and 230MHz. This is achieved by changing the external RF front-end components: L1, L2, L3, L4, C1, C2, C4, C5 and Xtal. The XE1218A FM receiver connects to the antenna via a differential input: pins RFI and RFG. The external components L4, C4 and C5 must tune the circuit to the incoming carrier frequency. L2 and C2 are calculated to tune the oscillator to the desired incoming carrier frequency. Xtal is selected according to the desired input carrier frequency, L3 relaxes the oscillator's Q factor to insure greater reception stability. Reception sensitivity is determined through the LNA's external tank circuit: C1 and L1. Two types of audio outputs can be selected: OUT (line out, 10k output impedance) to connect to an external audio processing circuit or amplifier and EAR for direct connection to an earphone. An external R1 is used to adjust the volume through pin VOL. The internal RF and audio blocks each have their own supply voltage as well as a common VDD. Clean voltage must be supplied to each of these supplies (VCCR, VCCA, VCCO and VDD). 4 D0204-157 Datasheet XE1218A: Low Power single die FM receiver 2.3 Application example To tune the above circuit to a carrier frequency of 160.325MHz, the following external components must be implemented: L1 56nH-5% C1 12pF-5% C5 L2 56nH-5% C2 10pF- 15pF-5% R1 L3 180nH-5% C3 10nF-5% Xtal L4 120nH - 5% C4 22pF-5% A1 The value of the capacitors given here may change slightly for different PCBs. 2pF - 6pF-5% 100k - 10% 160.325MHz Wire l > 40mm 3. Electrical characteristics 3.1 Absolute maximum ratings Parameter Supply voltage Storage Temperature Min -0.3V -55C Max 2.5V +125C Stress beyond those listed under absolute maximum ratings may cause permanent damage to the XE1218 device. These are stress ratings only, and functional operation of the device at these or any other condition beyond those under "recommended operating conditions" is not implied. Exposure to "absolute maximum ratings" conditions for extended periods may affect the device reliability. 3.2 Recommended operating conditions and electrical specifications General conditions: Temp = 25C, VDD= 1.3V, Carrier Frequency=160MHz, unless otherwise specified Symbol Description Condition Electrical supply parameters Min Typ. Max Unit VDD IDD TEMP RF-IN F-DEV LO-D RFS ACR Power supply Supply current 1.1 Receiver ON, without earphone PA enabled Operating temperature range Radio Frequency parameters Input range Maximum deviation of the incoming modulated signal Crystal ageing and temperature drift not accounted for fmodulated = 1kHz, fdev= 3kHz funwanted = fRfin + 100kHz fmodulated = 1kHz, fdev= 3kHz Pin = RFS + 10dBm SINAD = 10dB Audio parameters Fdev = 3kHz Only relevant if using the direct earphone connection fmodulated= 1kHz, fdev = 5kHz Rvol = 100k Pin = -60dBm, BW = 20kHz -10 130 1.3 2.5 1.6 4.5 +40 230 8 20 V mA C MHz kHz ppm dBm dB Carrier frequency Deviation frequency Local Oscillator shift RF input sensitivity Adjacent channel rejection -100 50 AOB AOD Audio Output bandwidth (typical) Audio distortion on PA output (EAR) 0.1 2 6 8 kHz % 5 D0204-157 Datasheet XE1218A: Low Power single die FM receiver Symbol Description Condition Audio parameters cont. fmodulated= 1kHz, fdev = 3kHz Rvol = 100k Pin = -60dBm, BW = 6kHz Only in use for direct earphone connection to the PA (EAR) Impedance of the earphone that directly connects to the EAR output Min Typ. Max Unit ASN DC-EAR Z-EAR Audio SNR on PA output (EAR) DC voltage on EAR output External earphone impedance 40 150 200 450 1000 dB mV 4. Interconnections The XE1218A is delivered in bare die. The complete FM receiver functionality requires 16 bond wire connections from the die to the 1st level substrate (for EAR functionality, 18 wire bonds for the line out connection). The die measures 21.8mm2 (4.9mm x 4.45mm). For prototyping purposes, the XE1218A is also available in a TQFP44 package, see details on the next page. 4.1 Bare die pad out 4900 m AUD EAR VDD VCCA VCCO VSS LON LOP XN XP 4450m RFT VCCR VOL OUT RFI RFG VM Origin reference (0,0) 6 D0204-157 Datasheet XE1218A: Low Power single die FM receiver 4.2 Pad coordinates The pad coordinates below are referenced to the lower left corner of the die (see picture above). The reference is to the center of the bond pad. Pad name LON LOP XN XP RFT VCCR RFI RFG X,Y coordinates (m) 145, 3569 145, 3391 145, 2843 145, 2664 145, 1944 145, 1765 145, 1283 145, 1105 Pad name AUD EAR VDD VCCA VCCO VSS VOL OUT VM X,Y coordinates (m) 145, 4166 4629, 4141 4629, 3962 4629, 3782 4629, 3526 4629, 3270 4629, 2323 4629, 1809 4629, 757 4.3 XE1218A packaging The following TQFP package is not currently qualified for production volumes. It serves solely prototyping purposes. 7 D0204-157 Datasheet XE1218A: Low Power single die FM receiver 4.4 TQFP44 pin-out Only the relevant signals are listed below. All other pins should remain N.C. (not connected) Pin name LON LOP XN XP RFT VCCR RFI RFG Pin number 4 3 6 5 7 8 10 11 Pin name EAR VDD VCCA VCCO VSS VOL OUT VM AUD Pin number 34 33 32 31 30 26 24 23 44 8 D0204-157 Datasheet XE1218A: Low Power single die FM receiver 5. Input - output signal description Pin Name LOP LON XP XN RFI RFG RFT Description Local oscillator tank Local oscillator tank Crystal oscillator connection Crystal oscillator connection RF signal input (differential to RFG) RF signal ground (differential to RFI) LNA tank circuit Functionality The integrated local oscillator is used to produce the mixer frequency to down convert the incoming carrier frequency. This local oscillator requires an external tank circuit, which must be tuned to select the desired crystal overtone. The crystal is connected between pins XP and XN. An inductance must be put in parallel. The incoming carrier frequency is fed to the LNA via a differential input (RFI and RFG). For best results, an external capacitive impedance matching circuit is required. The LNA has an external tank circuit to optimize its gain. The resonance frequency of this tank circuit must be adjusted to be the same as the incoming carrier frequency This is the supply voltage for the RF section of the XE1218A. It must be clean and de-coupled properly. This is the supply voltage for the digital and control circuitry of the XE1218A. It must be clean and decoupled properly. This is the ground reference. VDD, VCCA and VCCR are referenced to this pin. This is the supply voltage for the analog section of the XE1218A. It must be clean and de-coupled properly. The XE1218A audio circuitry requires an internal voltage multiplier. This multiplier requires and external capacitor to be connected to VM This pin must be connected to VDD This is used when the integrated PA is in use. An external potentiometer (100k to 1M) will allow varying the volume at the EAR output. 100k will give you a tuning range of 0dB to -10dB and 1M will equate to 0dB to -21.5dB High impedance audio output: impedance = 10k Earphone output, average 250mV, 3dB, speaker impedance must be between 200 and 1k This pin is only used when the line out (OUT) is selected. An additional de-coupling capacitor is needed for line out best performance Type Analog I/O Analog I/O Analog I/O Analog I/O Analog Input Analog ground Analog I/O VCCR VDD VSS VCCA VM VCCO VOL Supply voltage to the RF circuitry Supply voltage to the digital circuitry Ground reference Supply voltage to the analog circuitry External capacitor for voltage multiplier Supply for audio circuitry Volume control Analog supply Digital supply Digital ground Analog supply Analog I/O Supply input Analog input OUT EAR AUD Line out Earphone out Audio out de-coupling Analog output Analog output Analog output 9 D0204-157 Datasheet XE1218A: Low Power single die FM receiver 6. Application information 6.1 Recommended crystal oscillator The recommended characteristics of the crystal used for generating the local oscillator frequency (LO) are the following: Supplier: Telequarz Type: HSLX5132 Frequency: 160.325 MHz (7th overtone) Motional capacitance Cs = 0.2 fF 0.15 fF Calibration tolerance at 25 C: 10 ppm Stability over temperature range: 5 ppm Ageing in the first year: 3 ppm 6.2 Using a low impedance audio output The XE1218A provides two possible audio outputs: a) direct connection to an earphone and b) a high impedance line out (10k). Should a low impedance output be required to interface with an audio post processing stage, this output can be matched by using the EAR output of the XE1218A. The adaptation should be as follows: EAR 1k Low impedance line out 6.3 Using the high impedance line out OUT If the line out OUT pin is used on the XE1218A to interface to an analog audio post processing circuit such as a sound de-compounder or external power amplifier, a de-coupling capacitor must be connected to the pin AUD of the XE1218A. Please note that this capacitor is only necessary when the system uses the OUT connection. When the internal amplifier is used and an earphone is directly connected to the output EAR, the pin AUD must not remain connected. 4.7nF-5% AUD OUT High impedance line out (10k) 10 D0204-157 Datasheet XE1218A: Low Power single die FM receiver 6.4 Recommended antenna All antenna types need to be adapted with regards to the selected operating frequency. In the examples below the antennas are tuned for an incoming frequency of 160.350MHz (FO + FIF: 160.325MHz + 25kHz). The antenna can be a printed wire on the PCB, or real estate permitting a wire or a coil. In the case of a wire antenna, its length should be slightly above 40mm (Figure 1). It can either be printed straight on the PCB or a loose wire can be used. A magnetic coil antenna however is recommended because unlike a wire antenna, it is less sensitive to de-tuning by the proximity of the body. The coil is made of 1.8 turns of a 0.4mm diameter copper wire. The diameter of the antenna is 14mm for a typical coil inductance of 140nH (Figure 2). The coil is soldered in such a way as to be elevated from the PCB by at least 10mm, this is to reduce losses due to the ground plane effect of the board. The value of the capacitors given here may change slightly for different PCBs. D = 14mm L > 40mm 22pF RFI 120nH 2-10pF RFG Figure 1 Figure 2 2-10pF RFG H > 10mm 3.9pF RFI XEMICS 2002 All rights reserved. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice. No liability will be accepted by the publisher for any consequence of its use. Publication thereof does not convey nor imply any license under patent or other industrial or intellectual property rights. XEMICS PRODUCTS ARE NOT DESIGNED, INTENDED, AUTHORIZED OR WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT APPLICATIONS, DEVICES OR SYSTEMS OR OTHER CRITICAL APPLICATIONS. INCLUSION OF XEMICS PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE UNDERTAKEN SOLELY AT THE CUSTOMER'S OWN RISK. Should a customer purchase or use XEMICS products for any such unauthorized application, the customer shall indemnify and hold XEMICS and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs damages and attorney fees which could arise. 11 D0204-157 |
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