LTC5598IUF

FEATURES n n n LTC5598 5MHz to 1600MHz High Linearity Direct Quadrature Modulator DESCRIPTION The LTC®5598 is a direct I/Q modulator designed for high performance wireless applications, including wireless infrastructure. It allows direct modulation of an RF signal using differential baseband I and Q signals. It supports point-to-point microwave link, GSM, EDGE, CDMA, 700MHz band LTE, CDMA2000, CATV applications and other systems. It may also be configured as an image reject upconverting mixer, by applying 90° phase-shifted signals to the I and Q inputs. The I/Q baseband inputs consist of voltage-to-current converters that in turn drive double-balanced mixers. The outputs of these mixers are summed and applied to a buffer, which converts the differential mixer signals to a 50Ω single-ended buffered RF output. The four balanced I and Q baseband input ports are intended for DC coupling from a source with a common-mode voltage level of about 0.5V. The LO path consists of an LO buffer with single-ended or differential inputs, and precision quadrature generators that produce the LO drive for the mixers. The supply voltage range is 4.5V to 5.25V, with about 168mA current. L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. n n n n n n n n Frequency Range: 5MHz to 1600MHz High Output IP3: +27.7dBm at 140MHz +22.9dBm at 900MHz Low Output Noise Floor at 6MHz Offset: No Baseband AC Input: –161.2dBm/Hz POUT = 5.5dBm: –160dBm/Hz Low LO Feedthrough: –55dBm at 140MHz High Image Rejection: –50.4dBc at 140MHz Integrated LO Buffer and LO Quadrature Phase Generator 50Ω Single-Ended LO and RF Ports > 400MHz Baseband Bandwidth 24-Lead QFN 4mm × 4mm Package Pin-Compatible with Industry Standard Pin-Out Shut-down Mode APPLICATIONS n n n n n n n Point-to-Point Microwave Link Military Radio Basestation Transmitter GSM/EDGE/CDMA2K 700MHz LTE Basestation Transmitter Satellite Communication CATV/Cable Broadband Modulator 13.56MHz/UHF RFID Modulator TYPICAL APPLICATION 5MHz to 1600MHz Direct Conversion Transmitter Application 5V VCC LTC5598 I-DAC V-I I-CHANNEL 0 EN Q-CHANNEL Q-DAC BASEBAND GENERATOR V-I 5598 TA01 Noise Floor vs RF Output Power and Differential LO Input Power NOISE FLOOR AT 6MHz OFFSET (dBm/Hz) 4.7μF x2 RF = 5MHz TO 1600MHz –152 fLO = 140MHz; fBB = 2kHz; CW (NOTE 3) 20dBm 19.3dBm 13.4dBm 10.4dBm 8.4dBm 6.4dBm 1nF x2 –154 –156 PA 10nF 90 –158 –160 10nF 50Ω 10nF 470nF VCO/SYNTHESIZER –162 –14 –12 –10 –8 –6 –4 –2 0 2 4 RF OUTPUT POWER (dBm) 6 8 5598 TA02 5598f 1 LTC5598 ABSOLUTE MAXIMUM RATINGS (Note 1) PIN CONFIGURATION TOP VIEW BBMI BBPI VCC1 GND GND GND 18 VCC2 17 GNDRF 25 16 RF 15 NC 14 GNDRF 13 NC 7 CAPB 8 GND 9 10 11 12 BBMQ BBPQ GND GND Supply Voltage .........................................................5.6V Common Mode Level of BBPI, BBMI and BBPQ, BBMQ ...........................................................0.6V LOP LOM Input ....................................................20dBm , Voltage on Any Pin Not to Exceed ...................................–0.3V to VCC + 0.3V TJMAX .................................................................... 150°C Operating Temperature Range..................– 40°C to 85°C Storage Temperature Range...................–65°C to 150°C 24 23 22 21 20 19 EN 1 GND 2 LOP 3 LOM 4 GND 5 CAPA 6 UF PACKAGE 24-LEAD (4mm 4mm) PLASTIC QFN TJMAX = 150°C, θJA = 37°C/W EXPOSED PAD (PIN 25) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH LTC5598IUF#PBF TAPE AND REEL LTC5598IUF#TRPBF PART MARKING 5598 PACKAGE DESCRIPTION 24-Lead (4mm × 4mm) Plastic QFN TEMPERATURE RANGE –40°C to 85°C Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ 5598f 2 LTC5598 VCC = 5V, EN = 5V, TA = 25ºC, PLO = 0dBm, single-ended; BBPI, BBMI, BBPQ, BBMQ common-mode DC voltage VCMBB = 0.5VDC, I&Q baseband input signal = 100kHz CW, 0.8VPP,DIFF each, I&Q 90° shifted (lower side-band selection), unless otherwise noted. (Note 11) SYMBOL RF OUTPUT (RF) fRF S22, ON GV POUT OP1dB OIP2 OIP3 NFloor RF Frequency Range RF Output Return Loss Conversion Voltage Gain Absolute Output Power Output 1dB Compression Output 2nd Order Intercept Output 3rd Order Intercept RF Output Noise Floor (Notes 4, 5) (Notes 4, 6) No Baseband AC Input Signal (Note 3) POUT = 4.6dBm (Note 3) PLO, SE = 10dBm POUT = 5.5dBm (Note 3) PLO, DIFF = 20dBm (Note 7) EN = High (Note 7) EN = Low (Note 7) 20 • Log (VRF, OUT, 50Ω/VIN, DIFF, I or Q) 1VPP,DIFF on each I&Q Inputs (Notes 4, 5) (Notes 4, 6) No Baseband AC Input Signal (Note 3) (Note 7) EN = High (Note 7) EN = Low (Note 7) 20 • Log (VRF, OUT, 50Ω/VIN, DIFF, I or Q) 1VPP,DIFF on each I&Q Inputs (Notes 4, 5) (Notes 4, 6) No Baseband AC Input Signal (Note 3) POUT = 5.2dBm (Note 3) PLO, SE = 10dBm (Note 7) EN = High (Note 7) EN = Low (Note 7) –5.0 EN = High, 5MHz to 1600MHz 20 • Log (VRF, OUT, 50Ω/VIN, DIFF, I or Q) 1VPP,DIFF on each I&Q Inputs 5 to 1600 400 –68 –7.4 0.5 0.86 5 165 0.24 75 10 5.25 200 0.9 MHz dBm dBm dB dB MHz μA kΩ V VP-P V mA mA ns ns PARAMETER CONDITIONS MIN TYP MAX UNITS ELECTRICAL CHARACTERISTICS BASEBAND INPUTS (BBPI, BBMI, BBPQ, BBMQ) POWER SUPPLY (VCC1, VCC2) Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LTC5598 is guaranteed functional over the operating temperature range –40ºC to 85ºC. Note 3: At 6MHz offset from the LO signal frequency. 100nF between BBPI and BBMI, 100nF between BBPQ and BBMQ. Note 4: Baseband is driven by 2MHz and 2.1MHz tones with 1VPP,DIFF for two-tone signals at each I or Q input (0.5VPP,DIFF for each tone). Note 5: IM2 is measured at LO frequency – 4.1MHz. Note 6: IM3 is measured at LO frequency – 1.9 MHz and LO frequency – 2.2MHz. Note 7: Amplitude average of the characterization data set without image or LO feedthrough nulling (unadjusted). Note 8: RF power is within 10% of final value. Note 9: RF power is at least 30dB lower than in the ON state. Note 10: External coupling capacitors at pins LOP LOM and RF are 100pF , each. Note 11: Tests are performed as shown in the configuration of Figure 10. The LO power is applied to J3 while J5 is terminated with 50Ω to ground for single-ended LO drive. 5598f 4 LTC5598 VCC = 5V, EN = 5V, TA = 25ºC, fRF = fLO – fBB, PLO = 0dBm single-ended, BBPI, BBMI, BBPQ, BBMQ common-mode DC voltage VCMBB = 0.5VDC , I&Q baseband input signal = 100kHz, 0.8VPP,DIFF, two-tone baseband input signal = 2MHz, 2.1MHz, 0.5VPP,DIFF each tone, I&Q 90° shifted (lower side-band selection); fNOISE = fLO – 6MHz; unless otherwise noted. (Note 11) Supply Current vs Temperature 180 5.25V SUPPLY CURRENT (mA) 170 VOLTAGE GAIN (dB) 5.0V 160 –2 25 –3 OIP3 (dBm) 23 21 19 17 –1 TYPICAL PERFORMANCE CHARACTERISTICS Voltage Gain vs RF Frequency 29 27 Output IP3 vs RF Frequency 150 4.5V –4 5V, 25°C 5.25V, 25°C 4.5V, 25°C 5V, –40°C 5V, 85°C 10 100 RF FREQUENCY (MHz) 1000 5598 G02 5V, 25°C 5.25V, 25°C 4.5V, 25°C 5V, –40°C 5V, 85°C 10 100 RF FREQUENCY (MHz) 1000 5598 G03 140 –40 –15 10 35 TEMPERATURE (°C) 60 85 5598 G01 –5 Output IP2 vs RF Frequency 85 80 75 OIP2 (dBm) 70 65 60 55 10 Output 1dB Compression vs RF Frequency –40 LO Feedthrough to RF Output vs LO Frequency LO FEEDTHROUGH (dBm) 8 OP1dB (dBm) –50 6 4 5V, 25°C 5.25V, 25°C 4.5V, 25°C 5V, –40°C 5V, 85°C 10 100 RF FREQUENCY (MHz) 1000 5598 G05 5V, 25°C 5.25V, 25°C 4.5V, 25°C 5V, –40°C 5V, 85°C 10 100 RF FREQUENCY (MHz) 1000 5598 G04 –60 2 0 –70 5V, 25°C 5.25V, 25°C 4.5V, 25°C 5V, –40°C 5V, 85°C 10 100 LO FREQUENCY (MHz) 1000 5598 G06 Image Rejection vs LO Frequency –20 5V, 25°C 5.25V, 25°C 4.5V, 25°C 5V, –40°C 5V, 85°C –145 Noise Floor vs RF Frequency (No AC Baseband Input Signal) 5V, 25°C 5.25V, 25°C 4.5V, 25°C 5V, –40°C 5V, 85°C (NOTE 3) 0 RF Two-Tone Power (Each Tone), IM2 and IM3 vs RF Frequency –40 fRF, EACH = fLO – fBB1 –10 fIM3 = fLO + 2*fBB1 + fBB2 PRF,TONE (dBm) –20 fIM3 = fLO – 2*fBB1 + fBB2 –30 –40 –50 fIM2 = fLO – fBB1 – fBB2 –70 –80 –90 –100 –60 –50 IM2 (dBm), IM3 (dBm) –30 IMAGE REJECTION (dBc) –40 NOISE FLOOR (dBm/Hz) –150 –155 –50 –60 –160 –70 10 100 LO FREQUENCY (MHz) 1000 5598 G07 –165 10 100 RF FREQUENCY (MHz) 1000 5598 G08 –60 10 100 1000 RF FREQUENCY (MHz) 5598 G09 5598f 5 LTC5598 VCC = 5V, EN = 5V, TA = 25ºC, fRF = fLO – fBB, PLO = 0dBm single-ended, BBPI, BBMI, BBPQ, BBMQ common-mode DC voltage VCMBB = 0.5VDC , I&Q baseband input signal = 100kHz, 0.8VPP,DIFF, two-tone baseband input signal = 2MHz, 2.1MHz, 0.5VPP,DIFF each tone, I&Q 90° shifted (lower side-band selection); fNOISE = fLO – 6MHz; unless otherwise noted. (Note 11) RF Two-Tone Power (Each Tone), IM2 and IM3 vs Baseband Voltage and Temperature (fLO = 140MHz) 10 0 PRF, TONE (dBm) –10 –20 –30 –40 fRF, EACH = fLO –fBB1 fIM3 = fLO – 2*fBB1 + fBB2 fIM3 = fLO + 2*fBB1 + fBB2 fIM2 = fLO – fBB1 – fBB2 –30 –40 IM2 (dBm), IM3 (dBm) –50 –60 –70 –80 10 0 –10 fIM3 = fLO + 2*fBB1 + fBB2 –20 –30 f IM3 = fLO – 2*fBB1 + fBB2 –40 fIM2 = fLO – fBB1 – fBB2 –60 –70 –80 –5 fRF, EACH = fLO – fBB1 TYPICAL PERFORMANCE CHARACTERISTICS RF Two-Tone Power (Each Tone), IM2 and IM3 vs Baseband Voltage and Temperature (fLO = 900MHz) –30 –40 –2 VOLTAGE GAIN (dB) IM2 (dBm), IM3 (dBm) –50 –1 Voltage Gain vs RF Frequency (PLO = 10dBm) PLO = 10dBm PRF,TONE (dBm) –3 –4 5V, 25°C 5.25V, 25°C 4.5V, 25°C 5V, –40°C 5V, 85°C 10 100 RF FREQUENCY (MHz) 1000 5598 G12 –90 –50 0.1 1 I AND Q BASEBAND VOLTAGE (VPP DIFF, EACH TONE) , 5598 G10 –90 –50 0.1 1 I AND Q BASEBAND VOLTAGE (VPP DIFF, EACH TONE) , 5598 G11 Output IP3 vs RF Frequency (PLO = 10dBm) 29 27 25 OIP3 (dBm) OIP2 (dBm) 23 21 19 17 85 80 75 70 65 60 55 Output IP2 vs RF Frequency (PLO = 10dBm) 10 Output 1dB Compression vs RF Frequency (PLO = 10dBm) 8 OP1dB (dBm) 6 4 5V, 25°C 5.25V, 25°C 4.5V, 25°C 5V, –40°C 5V, 85°C 10 100 RF FREQUENCY (MHz) 1000 5598 G15 5V, 25°C 5.25V, 25°C 4.5V, 25°C 5V, –40°C 5V, 85°C 10 100 RF FREQUENCY (MHz) 1000 5598 G13 5V, 25°C 5.25V, 25°C 4.5V, 25°C 5V, –40°C 5V, 85°C 10 100 RF FREQUENCY (MHz) 1000 5598 G14 2 0 LO Feedthrough to RF Output vs LO Frequency (PLO = 10dBm) –40 –20 Image Rejection vs LO Frequency (PLO = 10dBm) 0 5V, 25°C 5.25V, 25°C 4.5V, 25°C 5V, –40°C 5V, 85°C PRF, TONE (dBm) RF Two-Tone Power (Each Tone), IM2 and IM3 vs RF Frequency (PLO = 10dBm) –40 fRF, EACH = fLO – fBB1 fIM3 = fLO + 2*fBB1 + fBB2 fIM3 = fLO – 2*fBB1 + fBB2 IM2 (dBm), IM3 (dBm) LO FEEDTHROUGH (dBm) –30 –50 IMAGE REJECTION (dBc) –40 –50 –60 5V, 25°C 5.25V, 25°C 4.5V, 25°C 5V, –40°C 5V, 85°C 10 100 LO FREQUENCY (MHz) 1000 5598 G16 –60 fIM2 = fLO – fBB1 – fBB2 –60 –100 –70 –70 10 100 LO FREQUENCY (MHz) 1000 5598 G17 10 100 RF FREQUENCY (MHz) 1000 5598 G18 5598f 6 LTC5598 VCC = 5V, EN = 5V, TA = 25ºC, fRF = fLO – fBB, fLO = 450MHz, PLO = 0dBm single-ended, BBPI, BBMI, BBPQ, BBMQ common-mode DC voltage VCMBB = 0.5VDC , I&Q baseband input signal = 100kHz, 0.8VPP,DIFF, two-tone baseband input signal = 2MHz, 2.1MHz, 0.5VPP,DIFF each tone, I&Q 90° shifted (lower side-band selection); fNOISE = fLO – 6MHz; unless otherwise noted. (Note 11) Noise Floor vs RF Frequency (PLO = 10dBm, No AC Baseband Input Signal) –145 5V, 25°C 5.25V, 25°C 4.5V, 25°C 5V, –40°C 5V, 85°C (NOTE 3) –40 LO FEEDTHROUGH (dBm) –40°C –60 –80 –100 PLO = 0dBm –120 –70 –165 –140 10 100 RF FREQUENCY (MHz) 1000 5598 G19 TYPICAL PERFORMANCE CHARACTERISTICS LO Feedthrough to RF Output vs LO Frequency for EN = Low 0 –10 IMAGE REJECTION (dBc) –20 –30 –40 –50 –60 Image Rejection vs LO Frequency (PLO = 10dBm) C8 = 0 NOISE FLOOR (dBm/Hz) –150 –155 PLO = 10dBm 85°C –160 C8 = 470nF 10 100 LO FREQUENCY (MHz) 1000 5598 G20 –80 10 100 LO FREQUENCY (MHz) 1000 5598 G20a Noise Floor vs RF Output Power and Differential LO Input Power –152 NOISE FLOOR AT 6MHz OFFSET (dBm/Hz) fLO = 140MHz; fBB = 2kHz; CW (NOTE 3) –154 20dBm 19.3dBm 13.4dBm 10.4dBm 8.4dBm 6.4dBm 50 PERCENTAGE (%) 40 30 20 10 0 60 Gain Distribution 85 C 25 C –40 C PERCENTAGE (%) 30 25 20 15 10 5 0 Output IP3 Distribution at 25°C –156 –158 –160 –162 –14 –12 –10 –8 –6 –4 –2 0 2 4 RF OUTPUT POWER (dBm) 6 8 –2.4 –2.3 –2.2 –2.1 GAIN (dB) –2 –1.9 5598 G21 24 24.4 24.8 25.2 25.6 26 26.4 26.8 27.2 OIP3 (dBm) 5598 G22 5598 G20b LO Feedthrough Distribution 25 85 C 25 C –40 C PERCENTAGE (%) 40 35 30 25 20 15 10 5 0 –70 –66 –62 –58 –54 –50 –46 –42 –38 LO FEEDTHROUGH (dBm) 5598 G23 Image Rejection Distribution 85 C 25 C –40 C PERCENTAGE (%) 70 60 Noise Floor Distribution 85 C 25 C –40 C 20 PERCENTAGE (%) NO RF 50 40 30 20 10 15 10 5 0 –70 –66 –62 –58 –54 –50 –46 –42 IMAGE REJECTION (dBc) 5598 G24 0 –162.4 –162 –161.6 –161.2 –160.8 –160.4 –160 NOISE FLOOR (dBm/Hz) 5598 G25 5598f 7 LTC5598 PIN FUNCTIONS EN (Pin 1): Enable Input. When the Enable Pin voltage is higher than 2 V, the IC is turned on. When the input voltage is less than 1 V, the IC is turned off. If not connected, the IC is enabled. GND (Pins 2, 5, 8, 11, 12, 19, 20, 23 and 25): Ground. Pins 2, 5, 8, 11, 12, 19, 20, 23 and exposed pad 25 are connected to each other internally. For best RF performance, pins 2, 5, 8, 11, 12, 19, 20, 23 and the Exposed Pad 25 should be connected to RF ground. LOP (Pin 3): Positive LO Input. This LO input is internally biased at about 2.3V. An AC de-coupling capacitor should be used at this pin to match to an external 50Ω source. LOM (Pin 4): Negative LO Input. This input is internally biased at about 2.3V. An AC de-coupling capacitor should be used at this pin via a 50Ω to ground for best OIP2 performance. CAPA, CAPB (Pins 6, 7): External capacitor pins. A capacitor between the CAPA and the CAPB pin can be used in order to improve the image rejection for frequencies below 100MHz. A capacitor value of 470nF is recommended. These pins are internally biased at about 2.3V. BBMQ, BBPQ (Pins 9, 10): Baseband Inputs for the Q-channel, each high input impedance. They should be externally biased at 0.5V common-mode level and not be left floating. Applied common-mode voltage must stay below 0.6VDC. NC (Pins 13, 15): No Connect. These pins are floating. GNDRF (Pins 14, 17): Ground. Pins 14 and 17 are connected to each other internally and function as the ground return for the RF output buffer. They are connected via back-to-back diodes to the exposed pad 25. For best LO suppression performance those pins should be grounded separately from the exposed paddle 25. For best RF performance, pins 14 and 17 should be connected to RF ground. RF (Pin 16): RF Output. The RF output is a DC-coupled single-ended output with approximately 50Ω output impedance at RF frequencies. An AC coupling capacitor should be used at this pin to connect to an external load. VCC (Pins 18, 24): Power Supply. It is recommended to use 1nF and 4.7μF capacitors for decoupling to ground on each of these pins. BBPI, BBMI (Pins 21, 22): Baseband Inputs for the Qchannel, each high input impedance. They should be externally biased at 0.5V common-mode level and not be left floating. Applied common-mode voltage must stay below 0.6VDC. Exposed Pad (Pin 25): Ground. This pin must be soldered to the printed circuit board ground plane. BLOCK DIAGRAM GND 20 BBPI 21 BBMI 22 V-I 23 25 VCC1 VCC2 24 18 13 NC 15 LTC5598 0 EN 1 90 16 RF BBPQ 10 BBMQ 9 V-I 14 GNDRF 17 2 5 GND 8 11 3 4 6 7 12 GND 19 5598 BD LOP LOM CAPA CAPB 5598f 8 LTC5598 APPLICATIONS INFORMATION The LTC5598 consists of I and Q input differential voltageto-current converters, I and Q up-conversion mixers, an RF output buffer, an LO quadrature phase generator and LO buffers. External I and Q baseband signals are applied to the differential baseband input pins, BBPI, BBMI, and BBPQ, BBMQ. These voltage signals are converted to currents and translated to RF frequency by means of double-balanced up-converting mixers. The mixer outputs are combined in an RF output buffer, which also transforms the output impedance to 50Ω. The center frequency of the resulting RF signal is equal to the LO signal frequency. The LO input drives a phase shifter which splits the LO signal into inphase and quadrature LO signals. These LO signals are then applied to on-chip buffers which drive the up-conversion mixers. In most applications, the LOP input is driven by the LO source via an optional matching network, while the LOM input is terminated with 50Ω to RF ground via a similar optional matching network. The RF output is single-ended and internally 50Ω matched. Baseband Interface The circuit is optimized for a common mode voltage of 0.5V which should be externally applied. The baseband pins should not be left floating because the internal PNP’s base current will pull the common mode voltage higher than the 0.6V limit. This condition may damage the part. In shut-down mode, it is recommended to have a termination to ground or to a 0.5V source with a value lower than 1kΩ. The PNP’s base current is about –68μA in normal operation. The baseband inputs (BBPI, BBMI, BBPQ, BBMQ) present a single-ended input impedance of about –7.4kΩ each. Because of the negative input impedance, it is important to keep the source resistance at each baseband input low enough such that the parallel value remains positive vs baseband frequency. At each of the four baseband inputs, a capacitor of 4pF in series with 30Ω is connected to ground. This is in parallel with a PNP emitter follower (see Figure 1). The baseband bandwidth depends on the source impedance. For a 25Ω source impedance, the baseband bandwidth (–1dB) is about 300MHz. If a 5.6nH series inductor is inserted in each of the four baseband connections, the –1dB baseband bandwidth increases to about 800MHz. It is recommended to include the baseband input impedance in the baseband lowpass filter design. The input impedance of each baseband input is given in Table 1. Table 1. Single-Ended BB Port Input Impedance vs Frequency for EN = High and VCMBB = 0.5VDC FREQUENCY (MHz) 0.1 1 2 4 8 16 30 60 100 140 200 300 400 500 600 BB INPUT IMPEDANCE –10578 – j263 –8436 – j1930 –6340 – j3143 –3672 – j3712 –1644 – j2833 –527 – j1765 –177 – j1015 –45.2 – j514 –13.2 – j306 –0.2 – j219 4.5 – j151 10.4 – j99.4 12.3 – j72.4 14.7 – j57.5 15.5 – j46.3 REFLECTION COEFFICIENT MAG 1.01 1.011 1.013 1.014 1.015 1.016 1.017 1.017 1.014 1 0.982 0.921 0.854 0.780 0.720 ANGLE –0.02 –0.15 –0.36 –0.78 –1.51 –2.98 –5.48 –11 –18.5 –25.7 –36.6 –52.9 –68.2 –79.9 –91.4 The baseband inputs should be driven differentially; otherwise, the even-order distortion products may degrade the overall linearity performance. Typically, a DAC will VCC2 = 5V BUFFER VCC1 = 5V FROM Q LOMI LOPI LTC5598 RF BBPI 30Ω 4pF VCMBB = 0.5VDC 4pF 30Ω BBMI GNDRF 55682 F01 GND Figure 1. Simplified Circuit Schematic of the LTC5598 (Only I-Half is Drawn) 5598f 9 LTC5598 APPLICATIONS INFORMATION be the signal source for the LTC5598. A reconstruction filter should be placed between the DAC output and the LTC5598’s baseband inputs. In Figure 2 a typical baseband interface is shown, using a fifth-order lowpass ladder filter. 0mA TO 20mA R1A 100 DAC C1 R1B 100 L1B C2 L2B C3 R2B 100 0.5VDC GND BBMI 5598 F02 L1A L2A 0.5VDC R2A 100 BBPI in Table 3. In Table 4 and 5, the LOP port input impedance is given for EN = High and Low under the condition of PLO = 10dBm. Figure 4 shows the LOP port return loss for the standard demo board (schematic is shown in Figure 10) when the LOM port is terminated with 50Ω to GND. The values of L1, L2, C9 and C10 are chosen such that the bandwidth for the LOP port of the standard demo board is maximized while meeting the LO input return loss S11, ON < –10dB. Table 2. LOP Port Input Impedance vs Frequency for EN = High and PLO = 0dBm (LOM AC Coupled With 50Ω to Ground). FREQUENCY (MHz) 0.1 1 2 4 8 16 30 60 100 200 400 800 1000 1250 1500 1800 LO INPUT IMPEDANCE 333 – j10.0 318 – j59.9 285 – j94.7 227 – j120 154 – j124 89.9 – j95.4 60.4 – j60.6 54.8 – j35.8 43.6 – j24.4 37.9 – j17.3 31.8 – j12.4 23.6 – j8.2 19.8 – j5.5 16.0 – j1.8 13.6 + j2.4 12.1 + j7.3 VCC1 0mA TO 20mA REFLECTION COEFFICIENT MAG 0.739 0.737 0.728 0.708 0.678 0.611 0.420 0.489 0.261 0.235 0.266 0.374 0.437 0.515 0.574 0.618 ANGLE –0.5 –3.3 –6.1 –10.6 –18.7 –33.0 –41.3 –51.5 –89.9 –113 –137 –156 –165 –175 174 162 Figure 2. Baseband Interface with 5th Order Filter and 0.5VCM DAC (Only I Channel is Shown) For each baseband pin, a 0 to 1V swing is developed corresponding to a DAC output current of 0mA to 20mA. The maximum sinusoidal single side-band RF output power is about +7.3dBm for full 0V to 1V swing on each I- and Q- channel baseband input (2VPP, DIFF). LO Section The internal LO chain consists of poly-phase phase shifters followed by LO buffers. The LOP input is designed as a single-ended input with about 50Ω input impedance. The LOM input should be terminated with 50Ω through a DC blocking capacitor. The LOP and LOM inputs can be driven differentially in case an exceptionally low large-signal output noise floor is required (see graph 5598 G20b). A simplified circuit schematic for the LOP, LOM, CAPA and CAPB inputs is given in Figure 3. A feedback path is implemented from the LO buffer outputs to the LO inputs in order to minimize offsets in the LO chain by storing the offsets on C5, C7 and C8 (see Figure 10). Optional capacitor C8 improves the image rejection below 100MHz (see graph 5598 G20a). Because of the feedback path, the input impedance for PLO = 0dBm is somewhat different than for PLO = 10dBm for the lower part of the operating frequency range. In Table 2, the LOP port input impedance vs frequency is given for EN = High and PLO = 0dBm. For EN = Low and PLO = 0dBm, the input impedance is given LOP LOM CAPB CAPA + 2.8V (4.3V IN SHUTDOWN) 5598 F03 Figure 3. Simplified Circuit Schematic for the LOP, LOM, CAPA and CAPB Inputs. 5598f 10 LTC5598 APPLICATIONS INFORMATION Table 3. LOP Port Input Impedance vs Frequency for EN = Low and PLO = 0dBm (LOM AC Coupled with 50Ω to Ground). FREQUENCY (MHz) 0.1 1 2 4 8 16 30 60 100 200 400 800 1000 1250 1500 1800 LO INPUT IMPEDANCE 1376 – j84.4 541 – j1593 177 – j877 75.3 – j452 49.2 – j228 43.3 – j117 40.7 – j64.1 39.1 – j34.6 37.6 – j23.8 33.4 – j16.4 27.5 – j11.1 20.1 – j4.9 17.5 – j1.6 15.3 + j2.1 13.8 + j5.6 12.8 + j9.7 REFLECTION COEFFICIENT MAG 0.930 0.980 0.977 0.965 0.918 0.784 0.585 0.382 0.296 0.275 0.320 0.430 0.479 0.532 0.571 0.605 ANGLE –0.3 –3.2 –6.2 –12.2 –23.6 –41.8 –62.7 –86 –102 –124 –145 –167 –176 175 167 157 Table 5. LOP Port Input Impedance vs Frequency for EN = Low and PLO = 10dBm (LOM AC Coupled with 50Ω to Ground). FREQUENCY (MHz) 0.1 1 2 4 8 16 30 60 100 200 400 800 1000 1250 1500 1800 LO INPUT IMPEDANCE 454 – j30.5 423 – j102 365 – j165 249 – j219 117 – j179 60.7 – j106 43.1 – j62.0 38.6 – j34.6 37.6 – j23.9 33.5 – j16.5 27.6 – j11.3 20.2 – j5.1 17.7 – j1.7 15.2 + j2.0 13.9 + j5.4 12.9 + j9.5 REFLECTION COEFFICIENT MAG 0.802 0.780 0.796 0.798 0.781 0.697 0.559 0.386 0.297 0.274 0.319 0.429 0.478 0.533 0.570 0.604 ANGLE –0.9 –3.2 –5.9 –11.4 –22.4 –40.3 –62.4 –86.7 –102 –124 –145 –166 –175 175 167 158 Table 4. LOP Port Input Impedance vs Frequency for EN = High and PLO = 10dBm (LOM AC Coupled with 50Ω to Ground). FREQUENCY (MHz) 0.1 1 2 4 8 16 30 60 100 200 400 800 1000 1250 1500 1800 LO INPUT IMPEDANCE 360-j14.8 349-j70.5 311-j113 240-j148 148-j146 81.3-j102 55.4-j61.6 45.7-j34.4 43.0-j24.1 38.0-j17.1 32.0-j12.5 23.6-j8.3 19.8-j5.6 15.8-j1.7 13.5+j2.4 12.0+j7.3 REFLECTION COEFFICIENT MAG 0.756 0.758 0.752 0.739 0.715 0.641 0.506 0.341 0.261 0.234 0.265 0.374 0.438 0.520 0.575 0.619 ANGLE RETURN LOSS (dB) 0 –5 –0.7 –3.2 –6.0 –10.9 –19.7 –35.2 –54.7 –77.4 –91.6 –114 –137 –156 –165 –176 174 162 –10 –15 –20 –25 1 EN = LOW; PLO = 0dBm EN = LOW; PLO = 10dBm EN = HIGH; PLO = 0dBm EN = HIGH; PLO = 10dBm C9, C10: 2.2pF; L1, L2: 3.3nH; C5, C7: 10nF 100 10 FREQUENCY (MHz) 1000 5598 F04 Figure 4. LOP Port Return Loss vs Frequency for Standard Board (See Figure 10) 5598f 11 LTC5598 APPLICATIONS INFORMATION The LOP port return loss for the low end of the operating frequency range can be optimized using extra 120Ω terminations at the LO inputs (replace C9 and C10 with 120Ω resistors, see Figure 10), and is shown in Figure 5. –4 C9, C10: 120Ω; L1, L2: 0Ω; C5, C7: 100nF EN = LOW; PLO = 0dBm EN = LOW; PLO = 10dBm –5 –6 RETURN LOSS (dB) The large-signal noise figure can be improved with a higher LO input power. However, if the LO input power is too large and causes internal clipping in the phase shifter section, the image rejection can be degraded rapidly. This clipping point depends on the supply voltage, LO frequency, temperature and single-ended vs differential LO drive. At fLO = 140MHz, VCC = 5V, T = 25°C and single-ended LO drive, this clipping point is at about 16.6dBm. For 4.5V it lowers to 14.6dBm. For differential drive with VCC = 5V it is about 20dBm. The differential LO port input impedance for EN = High and PLO = 10dBm is given in Table 6. –10 –12 EN = HIGH; PLO = 10dBm EN = HIGH; PLO = 0dBm 1 100 10 FREQUENCY (MHz) 1000 5598 F05 –14 Table 6. LOP - LOM Port Differential Input Impedance vs Frequency for EN = High and PLO = 10dBm FREQUENCY (MHz) 0.1 1.0 2.0 4.0 8.0 16 30 60 LO DIFFERENTIAL INPUT IMPEDANCE 642 – j25.7 626 – j112 572 – j204 429 – j305 222 – j287 102 – j181 64.2 – j104 50.9 – j58.9 46.2 – j40.2 37.4 – j28.6 28.3 – j19.4 20.0 – j10.6 17.5 – j7.9 16.6 – j2.7 17.3 + j3.3 20.6 + j10.2 Figure 5. LO Port Return Loss vs Frequency Optimized for Low Frequency (See Figure 10) The LOP port return loss for the high end of the operating frequency range can be optimized using slightly different values for C9, C10 and L1, L2 (see Figure 6). 0 –10 RETURN LOSS (dB) EN = LOW 100 200 400 –20 EN = HIGH –30 800 1000 1250 1500 1800 C9, C10: 2.7pF; L1, L2: 1.5nH; C5, C7: 10nF –40 1400 1600 1800 2000 1000 1200 FREQUENCY (MHz) 5598 F06 Figure 6. LO Port Return Loss vs Frequency Optimized for High Frequency (See Figure 10) RF Section After upconversion, the RF outputs of the I and Q mixers are combined. An on-chip buffer performs internal differential to single-ended conversion, while transforming the output impedance to 50Ω. Table 7 shows the RF port output impedance vs frequency for EN = High. The third-harmonic rejection on the applied LO signal is recommended to be equal or better than the desired image rejection performance since third-harmonic LO content can degrade the image rejection severely. Image rejection is not sensitive to second-harmonic LO content. 5598f 12 LTC5598 APPLICATIONS INFORMATION Table 7. RF Output Impedance vs Frequency for EN = High FREQUENCY (MHz) 0.1 1 2 4 8 16 30 60 100 200 400 800 1000 1250 1500 1800 RF OUTPUT IMPEDANCE 59.0 – j0.6 58.5 – j2.1 57.3 – j3.5 54.6 – j4.5 51.9 – j3.6 50.5 – j2.1 50.2 – j1.1 50 – j0.5 50 – j0.2 49.7 + j0 48.9 + j0.3 46.1 + j0.4 44.5 + j0.2 42.8 + j0 41.2 – j0.1 39.9 + j0.4 REFLECTION COEFFICIENT MAG 0.083 0.081 0.076 0.061 0.040 0.022 0.011 0.005 0.002 0.003 0.011 0.041 0.058 0.077 0.097 0.113 ANGLE –3.6 –12.7 –23.6 –41.6 –60.8 –74.8 –80 –86.5 –84.9 177.4 162 173.3 178 –179.7 –179.4 177.4 RETURN LOSS (dB) 0 EN = LOW –10 –20 –30 –40 –50 –60 1 C6 = 220nF SEE FIGURE 10 , 100 10 FREQUENCY (MHz) 1000 5598 F08 must be below 1V. If the EN pin is not connected, the chip is enabled. This EN = High condition is assured by the 125k on-chip pull-up resistor. It is important that the voltage at the EN pin does not exceed VCC by more than 0.3V. Should VCC2 1k 4.6V FROM INTERNAL MIXERS 1.8V 1V INTERNAL BIAS 1k 48Ω 5598 F07 48Ω 2.8V RF Figure 7. Simplified Circuit Schematic of the RF Output The RF port output impedance for EN = Low is given in Table 8. It is roughly equivalent to a 1.3pF capacitor to ground. Table 8. RF Output Impedance vs Frequency for EN = Low FREQUENCY (MHz) 100 200 400 800 1000 1250 1500 1800 LO INPUT IMPEDANCE 82.3 – j1223 51.1 – j618 35.3 – j310 24.4 – j148 20.4 – j114 17 – j87 14.7 – j68 13.1 – j54 REFLECTION COEFFICIENT MAG 0.995 0.987 0.965 0.906 0.878 0.847 0.818 0.785 ANGLE –4.6 –9.2 –18.1 –36.6 –46.4 –58.4 –70.7 –84.3 EN = HIGH Figure 8. RF Port Return Loss vs Frequency VCC1 In Figure 7 the simplified circuit schematic of the RF output buffer is drawn. A plot of the RF port return loss vs frequency is drawn in Figure 8 for EN = High and Low. Enable Interface Figure 9 shows a simplified schematic of the EN pin interface. The voltage necessary to turn on the LTC5598 is 2V. To disable (shut down) the chip, the enable voltage 125k 50k EN 2V 3V INTERNAL ENABLE CIRCUIT 5598 F09 Figure 9: EN Pin Interface 5598f 13 LTC5598 APPLICATIONS INFORMATION this occur, the supply current could be sourced through the EN pin ESD protection diodes, which are not designed to carry the full supply current, and damage may result. Evaluation Board Figure 10 shows the evaluation board schematic. A good ground connection is required for the exposed pad. If this is not done properly, the RF performance will degrade. Additionally, the exposed pad provides heat sinking for the part and minimizes the possibility of the chip overheating. Resistors R1 and R2 reduce the charging current in capacitors C1 and C4 (see Figure 10) and will reduce supply ringing during a fast power supply ramp-up in case an inductive cable is connected to the VCC and GND turrets. For EN = High, the voltage drop over R1 and R2 is about 0.15V. If a power supply is used that ramps up slower than 10V/μs and limits the overshoot on the supply below 5.6V, R1 and R2 can be omitted. The LTC5598 can be used for base-station applications with various modulation formats. Figure 13 shows a typical application. J1 BBMI J2 BBPI VCC Figure 11. Component Side of Evaluation Board C1 4.7μF C9 2.2pF J3 LOP EN 1 2 3 4 J5 LOM L2 3.3nH C10 2.2pF 5 C7 10nF 6 C2 1nF R1 1Ω R2 5.6Ω C3 1nF VCC2 RF NC 18 17 16 15 14 13 GND 25 U1 LTC5598 C6 10nF J4 RF OUT C4 4.7μF 24 23 22 21 20 19 VCC1 GND BBMI BBPI GND GND EN GND LOP LOM GND BBMQ CAPA CAPB GND BBPQ GND C5 L1 10nF 3.3nH GNDRF GNDRF NC GND 7 C8 470nF J6 GND BBMQ 8 9 10 11 12 J7 BBPQ Figure 12. Bottom Side of Evaluation Board BOARD NUMBER: DC1455A 5598 F10 Figure 10. Evaluation Circuit Schematic 5598f 14 LTC5598 APPLICATIONS INFORMATION 5V VCC 18, 24 21 I-DAC 22 V-I I-CHANNEL 1 EN 10 Q-DAC 9 Q-CHANNEL V-I 0 90 NC LTC5598 13, 15 16 10nF 14, 17 RF = 5MHz TO 1600MHz 1nF x2 4.7μF x2 PA BASEBAND GENERATOR 2, 5, 8, 11, 12, 19, 20, 23, 25 4 10nF 3 10nF 6 470nF 7 5598 F13 50Ω VCO/SYNTHESIZER Figure 13: 5MHz to 1600MHz Direct Conversion Transmitter Application PACKAGE DESCRIPTION UF Package 24-Lead (4mm × 4mm) Plastic QFN (Reference LTC DWG # 05-08-1697) 0.70 0.05 4.50 0.05 3.10 2.45 0.05 0.05 (4 SIDES) PACKAGE OUTLINE 0.25 0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS BOTTOM VIEW—EXPOSED PAD 0.75 0.05 R = 0.115 TYP PIN 1 NOTCH R = 0.20 TYP OR 0.35 45 CHAMFER 4.00 0.10 (4 SIDES) PIN 1 TOP MARK (NOTE 6) 23 24 0.40 1 2 0.10 2.45 0.10 (4-SIDES) (UF24) QFN 0105 0.200 REF 0.00 – 0.05 NOTE: 1. DRAWING PROPOSED TO BE MADE A JEDEC PACKAGE OUTLINE MO-220 VARIATION (WGGD-X)—TO BE APPROVED 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE, IF PRESENT 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 0.25 0.05 0.50 BSC 5598f Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 15 LTC5598 RELATED PARTS PART NUMBER Infrastructure LT5514 LT5517 LT5518 LT5519 LT5520 LT5521 LT5522 LT5527 LT5528 LT5554 LT5557 LT5560 LT5568 LT5571 DESCRIPTION Ultralow Distortion, IF Amplifier/ADC Driver with Digitally Controlled Gain 40MHz to 900MHz Quadrature Demodulator 1.5GHz to 2.4GHz High Linearity Direct Quadrature Modulator 0.7GHz to 1.4GHz High Linearity Upconverting Mixer 1.3GHz to 2.3GHz High Linearity Upconverting Mixer 10MHz to 3700MHz High Linearity Upconverting Mixer 600MHz to 2.7GHz High Signal Level Downconverting Mixer 400MHz to 3.7GHz High Signal Level Downconverting Mixer 1.5GHz to 2.4GHz High Linearity Direct Quadrature Modulator Broadband Ultra Low Distortion 7-Bit Digitally Controlled VGA 400MHz to 3.8GHz High Signal Level Downconverting Mixer Ultra-Low Power Active Mixer 700MHz to 1050MHz High Linearity Direct Quadrature Modulator COMMENTS 850MHz Bandwidth, 47dBm OIP3 at 100MHz, 10.5dB to 33dB Gain Control Range 21dBm IIP3, Integrated LO Quadrature Generator 22.8dBm OIP3 at 2GHz, –158.2dBm/Hz Noise Floor, 50Ω Single-Ended RF and LO Ports, 4-Channel W-CDMA ACPR = –64dBc at 2.14GHz 17.1dBm IIP3 at 1GHz, Integrated RF Output Transformer with 50Ω Matching, Single-Ended LO and RF Ports Operation 15.9dBm IIP3 at 1.9GHz, Integrated RF Output Transformer with 50Ω Matching, Single-Ended LO and RF Ports Operation 24.2dBm IIP3 at 1.95GHz, NF = 12.5dB, 3.15V to 5.25V Supply, Single-Ended LO Port Operation 4.5V to 5.25V Supply, 25dBm IIP3 at 900MHz, NF = 12.5dB, 50Ω Single-Ended RF and LO Ports IIP3 = 23.5dBm and NF = 12.5dBm at 1900MHz, 4.5V to 5.25V Supply, ICC = 78mA, Conversion Gain = 2dB. 21.8dBm OIP3 at 2GHz, –159.3dBm/Hz Noise Floor, 50Ω, 0.5VDC Baseband Interface, 4-Channel W-CDMA ACPR = –66dBc at 2.14GHz 48dBm OIP3 at 200MHz, 1.4nV/√Hz Input-Referred Noise, 2dB to 18dB Gain Range, 0.125dB Gain Step Size IIP3 = 23.7dBm at 2600MHz, 23.5dBm at 3600MHz, ICC = 82mA at 3.3V 10mA Supply Current, 10dBm IIP3, 10dB NF, Usable as Up- or Down-Converter. 22.9dBm OIP3 at 850MHz, –160.3dBm/Hz Noise Floor, 50Ω, 0.5VDC Baseband Interface, 3-Ch CDMA2000 ACPR = –71.4dBc at 850MHz 21.7dBm OIP3 at 900MHz, –159dBm/Hz Noise Floor, High-Ohmic 0.5VDC Baseband Interface 21.6dBm OIP3 at 2GHz, –158.6dBm/Hz Noise Floor, High-Ohmic 0.5VDC Baseband Interface, 4-Ch W-CDMA ACPR = –67.7dBc at 2.14GHz 50Ω, Single-Ended RF and LO Ports, 28dBm IIP3 at 900MHz, 13.2dBm P1dB, 0.04dB I/Q Gain Mismatch, 0.4° I/Q Phase Mismatch 27.3dBm OIP3 at 2.14GHz, 9.9dB Noise Floor, 2.6dB Conversion Gain, –35dBm LO Leakage 300MHz to 3GHz, Temperature Compensated, 2.7V to 6V Supply 100kHz to 1GHz, Temperature Compensated, 2.7V to 6V Supply 44dB Dynamic Range, Temperature Compensated, SC70 Package 36dB Dynamic Range, Low Power Consumption, SC70 Package Precision VOUT Offset Control, Shutdown, Adjustable Gain Precision VOUT Offset Control, Shutdown, Adjustable Offset Precision VOUT Offset Control, Adjustable Gain and Offset ±1dB Output Variation over Temperature, 38ns Response Time, Log Linear Response 25ns Response Time, Comparator Reference Input, Latch Enable Input, –26dBm to +12dBm Input Range Low Frequency to 1GHz, 83dB Log Linear Dynamic Range 75dB Dynamic Range, ±1dB Output Variation Over Temperature Fast Responding, up to 60dB Dynamic Range, ± 0.3dB Accuracy Over Temperature 10MHz to 6GHz, ±1dB Accuracy Over Temperature, 1.4mA at 3.3V Supply 5598f 620MHz - 1100MHz High Linearity Quadrature Modulator LT5572 1.5GHz to 2.5GHz High Linearity Direct Quadrature Modulator LT5575 800MHz to 2.7GHz High Linearity Direct Conversion I/Q Demodulator LT5579 1.5GHz to 3.8GHz High Linearity Upconverting Mixer RF Power Detectors LTC®5505 RF Power Detectors with >40dB Dynamic Range LTC5507 100kHz to 1000MHz RF Power Detector LTC5508 300MHz to 7GHz RF Power Detector LTC5509 300MHz to 3GHz RF Power Detector LTC5530 300MHz to 7GHz Precision RF Power Detector LTC5531 300MHz to 7GHz Precision RF Power Detector LTC5532 300MHz to 7GHz Precision RF Power Detector LT5534 50MHz to 3GHz Log RF Power Detector with 60dB Dynamic Range LTC5536 LT5537 LT5538 LT5570 LT5581 Precision 600MHz to 7GHz RF Power Detector with Fast Comparator Output Wide Dynamic Range Log RF/IF Detector 3.8GHz Wide Dynamic Range Log Detector 2.7GHz RMS Power Detector 40dB Dynamic Range RMS Detector 16 Linear Technology Corporation (408) 432-1900 ● FAX: (408) 434-0507 ● LT 0509 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 www.linear.com © LINEAR TECHNOLOGY CORPORATION 2009