GSM900

LMX2604 Triple-band VCO for GSM900/DCS1800/PCS1900 January 2004 LMX2604 Triple-band VCO for GSM900/DCS1800/PCS1900 General Description The LMX2604 is a fully integrated VCO (Voltage-Controlled Oscillator) IC designed for GSM900/DCS1800/PCS1900 triple-band application. The IC is ideal for use in the transmitter modulation loop by providing extremely small form factor and low phase noise. The IC has two VCOs, one for GSM and a second for DCS/PCS. The IC has two separate buffer amplifiers to drive an external high power amplifier, one for GSM900 band and the other one for DCS1800/ PCS1900 bands. The IC also has a differential buffer amplifier to drive a mixer for the offset PLL. The resonant circuits of the VCOs are fully integrated in the chip to ease the application of the IC. The high quality factor of the embedded tank circuit achieves very low phase noise characteristics at the VCO output. The only required external components are a couple of supply bypass capacitors and matching components. A control pin for controlling the oscillation frequency is shared by the two VCOs. The LMX2604 IC is provided in a 20-pin 4x4 LLP (Leadless Leadframe package). Features n On-chip Triple-band RF VCOs GSM: 880 MHz to 915 MHz DCS: 1710 MHz to 1785 MHz PCS: 1850 MHz to 1910 MHz n On-chip tank circuit n Low phase noise — -167 dBc/Hz @ 20 MHz offset in GSM band — -163 dBc/Hz @ 20 MHz offset in DCS band — -162 dBc/Hz @ 20 MHz offset in PCS band n High output power — +6 dBm in GSM mode — +6 dBm in DCS and PCS mode n Low current consumption — 18 mA in GSM mode — 15 mA in DCS and PCS mode n +2.6 V to +3.0 V supply voltage n 0.25 µm RF CMOS process n Small 20-pin 4x4 LLP package Applications n Transmit VCO for GSM, DCS, and PCS n Closed loop modulation systems Functional Block Diagram 20066101 FastLock™ is a trademark of National Semiconductor Corporation. TRI-STATE ® is a registered trademark of National Semiconductor Corporation. © 2004 National Semiconductor Corporation DS200661 www.national.com LMX2604 Connection Diagram 20-Pin 4x4 LLP (TM) Package 20066102 Pin Descriptions Pin Number 1 2,4,15 3 5 11,19 12 13 16 6,7,8,9,10,14,17,18,20 Note 1: The exposed die attach pad is grounded. Name CE GND (Note 1) MIXout BSW VDD GSMout DCSPCSout CPin NC I/O I — O I — O O I — Description Chip enable input pin. High=enable, Low=disable Ground pins Mixer output pin (RF output) Band switch input pin. High=DCS/PCS, Low=GSM Supply voltage pins RF output pin for VCO in GSM band RF output pin for VCO in DCS and PCS band Charge pump input pin No Connection, These pins must be left open Ordering Information Package 20-Pin LLP 20-Pin LLP Part Number LMX2604LQ LMX2604LQX Package Marking LMX2604LQ LMX2604LQ Media Transport 1000 Unit Tape and Reel 4500 Unit Tape and Reel NSC Drawing LQA20A LQA20A www.national.com 2 LMX2604 Absolute Maximum Ratings (Notes 3, 4, 5) Parameter Supply Voltage Input Voltage Input Current (Note 2) Storage Temperature Range Note 2: Maximum input current is for a logic pin, not the power pins. Symbol VDD VIN IIN TSTG Ratings -0.3 to 3.6 -0.3 to VDD+0.3 10 -65 to 150 Unit V V mA ˚C Recommended Operating Conditions Parameter Ambient Temperature Supply Voltage (to GND) Symbol TA VDD Condition VDD=3V Min -30 2.6 Typical 25 2.8 Max 85 3.0 Unit ˚C V Note 3: “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 do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Note 4: This Device is a high performance RF integrated circuit with an ESD rating < 2 kV and is ESD sensitive. Handling and assembly of this device should only be done at ESD-free workstations. Note 5: Stresses in excess of the absolute maximum ratings can cause permanent or latent damage to the device. These are absolute stress ratings only. Functional operation of the device is only implied at these or any other conditions in excess of those given in the operation sections of the data sheet. Exposure to absolute maximum ratings for extended periods can adversely affect device reliability Electrical Characteristics AC Characteristics (VDD=2.8V, TA=25˚C; unless otherwise noted) Symbol f Parameter Frequency Range Remarks GSM Band DCS Band PCS Band KVCO Tuning Sensitivity (Note 6) Output Power Output power of MIXout pin Phase Noise (GSM Band) GSM Band DCS Band PCS Band GSM Band DCS & PCS Band GSM Band DCS & PCS Band at 100 kHz offset L(f) at 400 kHz offset at 3 MHz offset (Note 7) at 20 MHz offset (Note 7) at 100 kHz offset L(f) Phase Noise (DCS Band) at 400 kHz offset at 3 MHz offset (Note 7) at 20 MHz offset (Note 7) at 100 kHz offset L(f) Phase Noise (PCS Band) Second Harmonic Suppression at 400 kHz offset at 3 MHz offset (Note 7) at 20 MHz offset (Note 7) All Bands at RF output port. Min 880 1710 1850 10 15 20 4 4 -5.5 -4.5 15 20 25 6 6 -3.5 -2.5 -120 -136 -152 -167 -112 -130 -146 -163 -110 -129 -145 -162 -20 -15 dBc -124 dBc/Hz -124 dBc/Hz -128 dBc/Hz Typ Max 915 1785 1910 20 25 30 8 8 -1.5 -0.5 dBm dBm MHz/V Units MHz MHz Pout PMIXout Note 6: Tuning Sensitivty is measured after coarse lock. Minimum and maximum limits are supported by characterization. Note 7: Supported by characterization 3 www.national.com LMX2604 Electrical Characteristics Symbol VIH VIL IIH IIL Parameter Logical Input High Voltage Logical Input Low Voltage Logical Input High Current Logical Input Low Current Input Capacitance IDD,GSM IDD,DCS/PCS Istd Supply Current (Note 8) Supply Current (Note 8) Standby Current (Continued) DC Characteristics (VDD=2.8V, TA=25˚C; unless otherwise noted) Condition Min 0.8VDD -0.3 -2.5 -2.5 5 18 15 21 18 2.5 Typ Max VDD+0.3 0.2VDD 2.5 2.5 Units V V µA µA pF mA mA µA Note 8: The current consumption in VCO and driver amplifier is all included Note 9: For CE, BSW, and CPin pins www.national.com 4 LMX2604 Typical Performance Characteristics : Phase Noise Typical phase noise characteristics in GSM band 20066161 Typical phase noise characteristics in DCS band 20066162 5 www.national.com LMX2604 Typical Performance Characteristics : Phase Noise (Continued) Typical phase noise characteristics in PCS band 20066163 www.national.com 6 LMX2604 Typical Performance Characteristic : GSMout Impedance GSMout 20066130 GSMout Frequency (MHz) 800 850 900 950 1000 Real (Ohms) 126 126 126 126 125 Imaginary (Ohms) -72 -74 -75 -77 -80 Absolute (Ohms) 146 146 146 147 149 7 www.national.com LMX2604 Typical Performance Characteristic : MIXout Impedance, GSM MIXout, GSM 20066131 MIXout, GSM Frequency (MHz) 800 850 900 950 1000 Real (Ohms) 141 133 126 120 115 Imaginary (Ohms) -256 -249 -243 -237 -232 Absolute (Ohms) 292 282 274 266 259 www.national.com 8 LMX2604 Typical Performance Characteristic : DCSPCSout Impedance DCSPCSout 20066132 DCSPCSout Frequency (MHz) 1600 1650 1700 1750 1800 1850 1900 1950 2000 Real (Ohms) 80 78 77 76 73 71 68 64 57 Imaginary (Ohms) -54 -53 -51 -50 -49 -48 -48 -48 -51 Absolute (Ohms) 96 94 93 91 88 85 83 80 77 9 www.national.com LMX2604 Typical Performance Characteristic : MIXout Impedance, DCS/PCS MIXout, DCS/PCS 20066133 MIXout, DCSPCS Frequency (MHz) 1600 1650 1700 1750 1800 1850 1900 1950 2000 Real (Ohms) 66 65 64 66 64 63 62 61 59 Imaginary (Ohms) -164 -162 -160 -157 -157 -153 -150 -146 -143 Absolute (Ohms) 177 175 172 171 169 166 162 159 155 www.national.com 10 LMX2604 Functional Description PRODUCT DESCRIPTION The LMX2604 IC has two VCOs, which are configured as an LC resonant oscillator. The active components and tank elements are all integrated on the IC. The oscillator core and the tank circuit are designed to be immune to external noise such as supply and load variation. The IC is easy-to-use and occupies extremely small area in the board. Two output amplifiers are also integrated to deliver high output power of +6 dBm in GSM/DCS/PCS applications. The amplifiers isolate the oscillator cores from the external load, and drive the external 50 ohm load. The output driver is designed to have low noise floor and to reduce pulling by load variation. An additional amplifier to drive the mixer in the transmit PLL is also provided. Only an attenuator composed of a few passive elements is necessary to meet the power level of the mixer input of the transmit PLL. The frequency of the oscillator is controlled by the CPin pin, which is internally connected to the varactor. This control pin is connected to the loop filter of the modulation loop in the transmit path. Any additional noise on this tuning input is directly translated into FM noise, which can degrade the phase noise characteristics of the oscillator. Typically, the loop filter of the PLL provides an appropriately low impedance source at its output and thus proper additional filtering stage is often required to reduce the high frequency noise and spurious signals. FREQUENCY SELECTION AND POWER DOWN CONTROL The BSW pin selects the operating frequency band. The table below shows the appropriate settings with the CE pin. CE Low Low High High BSW Low High Low High Output X X Low Band (GSM) High Band (DCS/PCS) In real implementation, the component values of the tank circuit vary from the nominal value. The IC has built-in circuit to track the variation and compensate that kind of the variation during normal operation. This self-correction algorithm does not require any external control signal and elements. The figure below shows an application circuit of the LMX2604. The LMX2604 is developed for the use in a GSM handset as part of the transmitter PLL. To complete the offset PLL in the transmit path, several passive elements for the external loop filter should be also provided. The charge pump output port of the external transceiver IC is fed to the CPin pin. The locking process of the LMX2604 is composed of two stages. First, the internal control circuitry of the LMX2604 controls the fast frequency acquisition behavior of the LMX2604. After the frequency acquisition, the whole loop enters in its normal operating mode. Application Circuit of LMX2604 20066172 11 www.national.com LMX2604 Functional Description FREQUENCY ACQUISITION (Continued) On the rising edge of CE the VCO goes through a frequency acquisition mode which coarse locks the PLL to the approximate final frequency. This portion of the lock digitally sets the frequency such that the final tuning voltage on the CPin line of the VCO is approximately Vdd/2. Benefits of this system is the maximum required charge pump voltage is reduced as large frequency ranges may be tuned with a small tuning voltage. This makes the digitally tuned VCO different from conventional analog VCOs. Frequency Acquisition Timing Diagram 20066122 www.national.com 12 LMX2604 Physical Dimensions inches (millimeters) unless otherwise noted 20066107 20-Pin LLP (Leadless Leadframe package) Package Order Number LMX2604LQX for 4500 Unit Reel Order Number LMX2604LQ for 1000 Unit Reel NS Package Number LQA20 13 www.national.com LMX2604 Triple-band VCO for GSM900/DCS1800/PCS1900 Notes LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. BANNED SUBSTANCE COMPLIANCE National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2. 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