LT5525 High Linearity, Low Power Downconverting Mixer U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO The LT®5525 is a low power broadband mixer optimized for high linearity applications such as point-to-point data transmission, high performance radios and wireless infrastructure systems. The device includes an internally 50Ω matched high speed LO amplifier driving a double-balanced active mixer core. An integrated RF buffer amplifier provides excellent LO-RF isolation. The RF input balun and all associated 50Ω matching components are integrated. The IF ports can be easily matched across a broad range of frequencies for use in a wide variety of applications. Wide Input Frequency Range: 0.8GHz to 2.5GHz* Broadband LO and IF Operation High Input IP3: +17.6dBm at 1900MHz Typical Conversion Gain: –1.9dB at 1900MHz High LO-RF and LO-IF Isolation SSB Noise Figure: 15.1dB at 1900MHz Single-Ended 50Ω RF and LO Interface Integrated LO Buffer: –5dBm Drive Level Low Supply Current: 28mA Typ Enable Function Single 5V Supply 16-Lead QFN (4mm × 4mm) Package The LT5525 offers a high performance alternative to passive mixers. Unlike passive mixers, which require high LO drive levels, the LT5525 operates at significantly lower LO input levels and is much less sensitive to LO power level variations. U APPLICATIO S ■ ■ ■ Point-to-Point Data Communication Systems Wireless Infrastructure High Performance Radios High Linearity Receiver Applications , LTC and LT are registered trademarks of Linear Technology Corporation. *Operation over a wider frequency range is achievable with reduced performance. Consult factory for more information. U ■ TYPICAL APPLICATIO High Signal Level Frequency Downconversion 0.01µF EN VCC2 IF Output Power and IM3 vs RF Input Power (Two Input Tones) VCC 5V DC 0 VCC1 –10 100pF 1900MHz 1900MHz LNA RF + IF + IF – RF – GND LT5525 1.2pF 150nH 4:1 VGA ADC –20 –30 POUT –40 –50 –60 –70 –80 –90 IM3 –100 –20 LO+ LO – LO INPUT –5dBm 150nH 140MHz OUTPUT POWER (dBm/TONE) BIAS TA = 25°C fRF = 1900MHz fLO = 1760MHz fIF = 140MHz PLO = –5dBm –10 –15 –5 RF INPUT POWER (dBm/TONE) 0 5525 TA01 5525 TA02 5525f 1 LT5525 W U U U W W W ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION (Note 1) Supply Voltage ...................................................... 5.5V Enable Voltage ............................... –0.3V to VCC + 0.3V LO Input Power ............................................... +10dBm LO+ to LO– Differential DC Voltage ......................... ±1V LO+ and LO– Common Mode DC Voltage... –0.5V to VCC RF Input Power ................................................ +10dBm RF+ to RF– Differential DC Voltage ..................... ±0.13V RF+ and RF– Common Mode DC Voltage ... –0.5V to VCC IF+ and IF– Common Mode DC Voltage ................... 5.5V Operating Temperature Range ................ – 40°C to 85°C Storage Temperature Range ................. – 65°C to 125°C Junction Temperature (TJ)................................... 125°C ORDER PART NUMBER NC LO– LO+ NC TOP VIEW 16 15 14 13 NC 1 LT5525EUF 12 GND RF + 2 11 IF+ 17 RF – 3 10 IF– 6 7 8 EN VCC2 NC 9 GND 5 VCC1 NC 4 UF PART MARKING UF PACKAGE 16-LEAD (4mm × 4mm) PLASTIC QFN 5525 TJMAX = 125°C, θJA = 37°C/W EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB. NC PINS SHOULD BE GROUNDED Consult LTC Marketing for parts specified with wider operating temperature ranges. DC ELECTRICAL CHARACTERISTICS VCC = 5V, EN = 3V, TA = 25°C (Note 3), unless otherwise noted. Test circuit shown in Figure 1. PARAMETER CONDITIONS MIN TYP MAX UNITS Supply Voltage (Note 6) 3.6 5 5.3 V Supply Current VCC = 5V 33 mA Shutdown Current EN = Low 100 µA Power Supply Requirements (VCC) 28 Enable (EN) Low = Off, High = On EN Input High Voltage (On) 3 V EN Input Low Voltage (Off) Enable Pin Input Current 0.3 EN = 5V EN = 0V V 55 0.1 µA µA Turn-On Time (Note 5) 3 µs Turn-Off Time (Note 5) 6 µs AC ELECTRICAL CHARACTERISTICS (Notes 2, 3) PARAMETER CONDITIONS RF Input Frequency Range (Note 4) Requires RF Matching Below 1300MHz MIN LO Input Frequency Range (Note 4) IF Output Frequency Range (Note 4) Requires IF Matching TYP MAX UNITS 800 to 2500 MHz 500 to 3000 MHz 0.1 to 1000 MHz VCC = 5V, EN = 3V, TA = 25°C. Test circuit shown in Figure 1. (Notes 2, 3) PARAMETER CONDITIONS RF Input Return Loss ZO = 50Ω 15 dB LO Input Return Loss ZO = 50Ω, External DC Blocks 15 dB IF Output Return Loss ZO = 50Ω, External Match 15 dB LO Input Power MIN TYP –10 to 0 MAX UNITS dBm 5525f 2 LT5525 AC ELECTRICAL CHARACTERISTICS VCC = 5V, EN = 3V, TA = 25°C, PRF = –15dBm (–15dBm/tone for 2-tone IIP3 tests, ∆f = 1MHz), fLO = fRF – 140MHz, PLO = –5dBm, IF output measured at 140MHz, unless otherwise noted. Test circuit shown in Figure 1. (Notes 2, 3) PARAMETER CONDITIONS Conversion Gain fRF = 900MHz fRF = 1900MHz fRF = 2100MHz fRF = 2500MHz MIN TYP –2.6 –1.9 –2.0 –2.0 MAX UNITS dB dB dB dB Conversion Gain vs Temperature TA = –40°C to 85°C –0.020 dB/°C Input 3rd Order Intercept fRF = 900MHz fRF = 1900MHz fRF = 2100MHz fRF = 2500MHz 21.0 17.6 17.6 12.0 dBm dBm dBm dBm Single Sideband Noise Figure fRF = 900MHz fRF = 1900MHz fRF = 2100MHz fRF = 2500MHz 14.0 15.1 15.6 15.6 dB dB dB dB LO to RF Leakage fLO = 500MHz to 1000MHz fLO = 1000MHz to 3000MHz ≤–50 ≤–43 dBm dBm LO to IF Leakage fLO = 500MHz to 1400MHz fLO = 1400MHz to 3000MHz ≤–50 ≤–39 dBm dBm RF to LO Isolation fRF = 500MHz to 3000MHz >38 dB RF to IF Isolation fRF = 900MHz fRF = 1900MHz fRF = 2100MHz fRF = 2500MHz 62 42 40 33 dB dB dB dB Input 1dB Compression fRF = 900MHz fRF = 1900MHz fRF = 2100MHz fRF = 2500MHz 7.6 4 4 3 dBm dBm dBm dBm 2RF-2LO Output Spurious Product (fRF = fLO + fIF/2) 900MHz: fRF = 830MHz at –15dBm 1900MHz: fRF = 1830MHz at –15dBm 2100MHz: fRF = 2030MHz at –15dBm 2500MHz: fRF = 2430Hz at –15dBm –63 –53 –45 –42 dBc dBc dBc dBc 3RF-3LO Output Spurious Product (fRF = fLO + fIF/3) 900MHz: fRF = 806.67MHz at –15dBm 1900MHz: fRF = 1806.67MHz at –15dBm 2100MHz: fRF = 2006.67MHz at –15dBm 2500MHz: fRF = 2406.67Hz at –15dBm –74 –59 –59 –60 dBc dBc dBc dBc Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The performance is measured with the test circuit shown in Figure 1. For 900MHz measurements, C1 = 3.9pF. For all other measurements, C1 is not used. Note 3: Specifications over the –40°C to 85°C temperature range are assured by design, characterization and correlation with statistical process controls. Note 4: Operation over a wider frequency range is possible with reduced performance. Consult the factory for information and assistance. Note 5: Turn-on and turn-off times correspond to a change in the output level of 40dB. Note 6: The part is operable below 3.6V with reduced performance. 5525f 3 LT5525 U W TYPICAL AC PERFOR A CE CHARACTERISTICS VCC = 5V, EN = 3V, TA = 25°C, fRF = 1900MHz, PRF = –15dBm (–15dBm/tone for 2-tone IIP3 tests, ∆f = 1MHz), fLO = fRF – 140MHz, PLO = –5dBm, IF output measured at 140MHz, unless otherwise noted. Test circuit shown in Figure 1. Conversion Gain and IIP3 vs RF Frequency (Low Side LO) Conversion Gain and IIP3 vs RF Frequency (High Side LO) 25 SSB NF vs RF Frequency 25 20 19 20 IIP3 10 25°C 85°C –40°C 5 GAIN 15 10 25°C 85°C –40°C 5 0 17 NOISE FIGURE (dB) 15 0 18 IIP3 GAIN (dB), IIP3 (dBm) GAIN (dB), IIP3 (dBm) 20 16 HIGH SIDE LO 15 14 LOW SIDE LO 13 GAIN 12 11 –5 900 1100 1300 1500 1700 1900 2100 2300 2500 RF FREQUENCY (MHz) –5 900 1100 1300 1500 1700 1900 2100 2300 2500 RF FREQUENCY (MHz) 5525 G01 5525 G02 Conversion Gain and IIP3 vs LO Input Power 20 10 25°C 85°C –40°C 0 0 –10 –20 18 –30 LEAKAGE (dBm) NOISE FIGURE (dB) GAIN (dB), IIP3 (dBm) IIP3 LO-IF, LO-RF and RF-LO Leakage vs Frequency 25°C 85°C –40°C 19 20 5 5525 G03 SSB Noise Figure vs LO Input Power 25 15 12 900 1100 1300 1500 1700 1900 2100 2300 2500 RF FREQUENCY (MHz) 17 16 15 –40 –70 2 –90 12 –14 –12 –10 –8 –6 –4 –2 LO INPUT POWER (dBm) 4 LO-IF –80 13 –5 –16 –14 –12 –10 –8 –6 –4 –2 0 LO INPUT POWER (dBm) RF-LO –60 14 GAIN LO-RF –50 5525 G04 0 2 –100 500 1000 2000 2500 1500 FREQUENCY (MHz) 5525 G06 5525 G05 Conversion Gain and IIP3 vs Supply Voltage RF, LO and IF Port Return Loss vs Frequency 25 0 20 –5 3000 IF Output Power and IM3 vs RF Input Power (Two Input Tones) 0 10 25°C 85°C –40°C IIP3 5 0 OUTPUT POWER (dBm/TONE) 15 RETURN LOSS (dB) GAIN (dB), IIP3 (dBm) –10 RF –10 LO –15 –20 IF GAIN –25 –20 –30 POUT –40 –50 –60 –70 –80 IM3 25°C 85°C –40°C –90 –5 2.8 –30 3.2 4.4 4 4.8 3.6 SUPPLY VOLTAGE (V) 5.2 5.6 5525 G07 0 500 1000 1500 2000 FREQUENCY (MHz) 2500 3000 5525 G08 –100 –20 –10 –15 –5 RF INPUT POWER (dBm/TONE) 0 5525 G09 5525f 4 LT5525 U W TYPICAL AC PERFOR A CE CHARACTERISTICS VCC = 5V, EN = 3V, TA = 25°C, fRF = 1900MHz, PRF = –15dBm (–15dBm/tone for 2-tone IIP3 tests, ∆f = 1MHz), fLO = fRF – 140MHz, PLO = –5dBm, IF output measured at 140MHz, unless otherwise noted. Test circuit shown in Figure 1. IFOUT, 2 × 2 and 3 × 3 Spurs vs RF Input Power 2 × 2 and 3 × 3 Spurs vs LO Input Power 10 –30 0 IF OUT fRF = 1900MHz OUTPUT POWER (dBm) OUTPUT POWER (dBm) –10 –40 –20 –30 3RF-3LO fRF = 1806.67MHz –40 –50 –60 –70 2RF-2LO fRF = 1830MHz –80 TA = 25°C fLO = 1760MHz fIF = 140MHz –90 –100 –20 –15 –10 –5 RF INPUT POWER (dBm) TA = 25°C fLO = 1760MHz fIF = 140MHz –50 –60 2RF-2LO fRF = 1830MHz –70 –80 3RF-3LO fRF = 1806.67MHz –90 0 –100 –16 –12 –8 –4 5525 G10 5525 G11 U W TYPICAL DC PERFOR A CE CHARACTERISTICS Supply Current vs Supply Voltage 25°C 85°C –40°C SHUTDOWN CURRENT (µA) SUPPLY CURRENT (mA) 30 28 26 24 22 20 18 25°C 85°C –40°C 16 2.8 3.2 3.6 4 4.4 4.8 SUPPLY VOLTAGE (V) 5.2 5.6 5525 G12 Test circuit shown in Figure 1. Shutdown Current vs Supply Voltage 20 32 14 4 0 LO INPUT POWER (dBm) 15 10 5 0 2.8 3.2 3.6 4 4.4 4.8 SUPPLY VOLTAGE (V) 5.2 5.6 5525 G13 5525f 5 LT5525 U U U PI FU CTIO S NC (Pins 1, 4, 8, 13, 16): Not Connected Internally. These pins should be grounded on the circuit board for improved LO-to-RF and LO-to-IF isolation. GND (Pins 9, 12): Ground. These pins are internally connected to the Exposed Pad for better isolation. They should be connected to ground on the circuit board, though they are not intended to replace the primary grounding through the Exposed Pad of the package. RF+, RF– (Pins 2, 3): Differential Inputs for the RF Signal. One RF input pin may be DC connected to a low impedance ground to realize a 50Ω single-ended input at the other RF pin. No external matching components are required. A DC voltage should not be applied across these pins, as they are internally connected through a transformer winding. IF– and IF+ (Pins 10, 11): Differential Outputs for the IF Signal. An impedance transformation may be required to match the outputs. These pins must be connected to VCC through impedance matching inductors, RF chokes or a transformer center-tap. EN (Pin 5): Enable Pin. When the input voltage is higher than 3V, the mixer circuits supplied through Pins 6, 7, 10 and 11 are enabled. When the input voltage is less than 0.3V, all circuits are disabled. Typical enable pin input current is 55µA for EN = 5V and 0.1µA when EN = 0V. LO–, LO+ (Pins 14, 15): Differential Inputs for the Local Oscillator Signal. The LO input is internally matched to 50Ω. The LO can be driven with a single-ended source through either LO input pin, with the other LO input pin connected to ground. There is an internal DC resistance across these pins of approximately 480Ω. Thus, a DC blocking capacitor should be used if the signal source has a DC voltage present. VCC1 (Pin 6): Power Supply Pin for the LO Buffer Circuits. Typical current consumption is 11mA. This pin should be externally connected to the other VCC pins and decoupled with 1µF and 0.01µF capacitors. Exposed Pad (Pin 17): Circuit Ground Return for the Entire IC. This must be soldered to the printed circuit board ground plane. VCC2 (Pin 7): Power Supply Pin for the Bias Circuits. Typical current consumption is 2.5mA. This pin should be externally connected to the other VCC pins and decoupled with 1µF and 0.01µF capacitors. W BLOCK DIAGRA 17 15 14 LO+ EXPOSED PAD LO– HIGH SPEED LO BUFFER 2 3 RF GND LINEAR AMPLIFIER + IF+ IF– RF – DOUBLEBALANCED MIXER GND 12 11 10 9 BIAS EN 5 VCC2 7 VCC1 6 5525 BD 5525f 6 LT5525 TEST CIRCUITS RF GND ER = 4.4 0.018" LOIN 1760MHz 0.062" DC 16 C1 OPTIONAL RFIN 1900MHz 1 17 NC NC 2 + RF 15 LO + 14 LO– 13 NC GND IF LT5525 3 4 GND NC 900MHz INPUT MATCHING: C1: 3.9pF L3 T2 C4 C3 L2 10 6 7 5 2 3 4 IFOUT 140MHz 8 C8 C2 VALUE SIZE PART NUMBER — 0402 Frequency Dependent C2 0.01µF 0402 AVX 04023C103JAT C3 1.2pF 0402 AVX 04025A1R2BAT C4 100pF 0402 AVX 04025A101JAT C8 1µF 0603 Taiyo Yuden LMK107BJ105MA T2 1 9 C1 L2, L3 GND VCC1 VCC2 NC 5 EN 12 + 11 IF – RF – EN REF DES 0.018" 150nH 1608 4:1 SM-22 5526 F01 VCC Toko LL1608-FSR15J M/A-COM ETC4-1-2 Figure 1. Test Schematic U W U U APPLICATIO S I FOR ATIO The LT5525 consists of a double-balanced mixer, RF balun, RF buffer amplifier, high speed limiting LO buffer and bias/enable circuits. The IC has been optimized for downconverter applications with RF input signals from 0.8GHz to 2.5GHz and LO signals from 500MHz to 3GHz. With proper matching, the IF output can be operated at frequencies from 0.1MHz to 1GHz. Operation over a wider frequency range is possible, though with reduced performance. The RF, LO and IF ports are all differential, though the RF and LO ports are internally matched to 50Ω for singleended drive. The LT5525 is characterized and production tested using single-ended RF and LO inputs. Low side or high side LO injection can be used. RF Input Port The mixer’s RF input, shown in Figure 2, consists of an integrated balun and a high linearity differential amplifier. The primary terminals of the balun are connected to the RF+ and RF– pins (Pins 2 and 3, respectively). The secondary side of the balun is internally connected to the amplifier’s differential inputs. For single-ended operation, the RF+ pin is grounded and the RF– pin becomes the RF input. It is also possible to ground the RF– pin and drive the RF+ pin, if desired. If the RF source has a DC voltage present, then a coupling capacitor must be used in series with the RF input pin. Otherwise, excessive DC current could damage the primary winding of the balun. 5525f 7 LT5525 U W U U APPLICATIO S I FOR ATIO OPTIONAL SERIES REACTANCE FOR LOW BAND OR HIGH BAND RFIN MATCHING 3 25 LT5525 RF+ RF– 5525 F02 GAIN AND NF (dB), IIP3 (dBm) 2 20 IIP3 15 SSB NF 10 TA = 25°C fIF = 140MHz LOW SIDE LO HIGH SIDE LO 5 0 GAIN Figure 2. RF Input Schematic As shown in Figure 3, the RF input return loss with no external matching is greater than 12dB from 1.3GHz to 2.3GHz. The RF input match can be shifted down to 800MHz by adding a series 3.9pF capacitor at the RF input. A series 1.2nH inductor can be added to shift the match up to 2.5GHz. Measured return losses with these external components are also shown in Figure 3. 0 RETURN LOSS (dB) –5 NO RF MATCHING –10 –15 –20 SERIES 1.2nH –25 SERIES 3.9pF –30 500 1000 1500 2000 2500 RF FREQUENCY (MHz) 3000 5525 F03 Figure 3. RF Input Return Loss Without and with External Matching Components Figure 4 illustrates the typical conversion gain, IIP3 and NF performance of the LT5525 when the RF input match is shifted lower in frequency using an external series 3.9pF capacitor on the RF input. RF input impedance and reflection coefficient (S11) versus frequency are shown in Table 1. The listed data is referenced to the RF– pin with the RF+ pin grounded (no external matching). This information can be used to simulate board-level interfacing to an input filter, or to design a broadband input matching network. –5 800 850 900 950 1000 1050 1100 1150 1200 RF FREQUENCY (MHz) 5525 F04 Figure 4. Typical Gain, IIP3 and NF with Series 3.9pF Matching Capacitor Table 1. RF Port Input Impedance vs Frequency FREQUENCY (MHz) 50 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500 2700 3000 INPUT IMPEDANCE 10.4 + j2.63 18.1 + j23.7 25.8 + j30.7 36.5 + j34.5 48.4 + j33.3 59.5 + j25.7 65.9 + j13.1 65.0 – j1.0 59.0 – j12.2 50.2 – j19.0 41.8 – j22.1 34.9 – j22.7 29.1 – j21.9 23.2 – j19.1 REFLECTION COEFFICIENT MAG ANGLE 0.675 174 0.551 124 0.478 106 0.398 90 0.321 74 0.244 57 0.177 33 0.131 –3 0.138 –47 0.187 –79 0.250 –97 0.311 –109 0.369 –118 0.435 –130 A broadband RF input match can be easily realized by using both the series capacitor and series inductor as shown in Figure 5. This network provides good return loss at both lower and higher frequencies simultaneously, while maintaining good mid-band return loss. The broadband return loss is plotted in Figure 6. The return loss is better than 12dB from 700MHz to 2.6GHz using the element values of Figure 5. LO Input Port The LO buffer amplifier consists of high speed limiting differential amplifiers designed to drive the mixer core for high linearity. The LO+ and LO– pins are designed for 5525f 8 LT5525 U W U U APPLICATIO S I FOR ATIO 2 0 LT5525 RF+ RFIN C5 4.7pF L3 1.5nH 3 RETURN LOSS (dB) –5 RF– –10 –15 5525 F05 Figure 5. Wideband RF Input Matching –20 0 500 0 2500 1000 1500 2000 FREQUENCY (MHz) 3000 5525 F08 RETURN LOSS (dB) –5 Figure 8. LO Input Return Loss NO EXTERNAL RF MATCHING –10 The LO port input impedance and reflection coefficient (S11) versus frequency are shown in Table 2. The listed data is referenced to the LO+ pin with the LO– pin grounded. –15 –20 SERIES 1.5nH AND 4.7pF Table 2. Single-Ended LO Input Impedance –25 –30 500 1000 3000 1500 2000 2500 RF FREQUENCY (MHz) 5525 F06 Figure 6. RF Input Return Loss Using Wideband Matching Network single-ended drive, though differential drive can be used if desired. The LO input is internally matched to 50Ω. A simplified schematic for the LO input is shown in Figure 7. Measured return loss is shown in Figure 8. If the LO source has a DC voltage present, then a coupling capacitor should be used in series with the LO input pin due to the internal resistive match. 14 LT5525 LO– FREQUENCY (MHz) 100 250 500 1000 1500 2000 2500 3000 INPUT IMPEDANCE 93.1 – j121 55.8 – j54 47.7 – j28 42.3 – j14 38.5 – j9.3 35.8 – j7.8 34.8 – j7.8 34.2 – j8.7 REFLECTION COEFFICIENT MAG ANGLE 0.686 –30 0.457 –57 0.276 –79 0.171 –110 0.166 –135 0.187 –146 0.281 –148 0.214 –149 IF Output Port A simplified schematic of the IF output circuit is shown in Figure 9. The output pins, IF+ and IF–, are internally connected to the collectors of the mixer switching transistors. Both pins must be biased at the supply voltage, which can be applied through the center-tap of a transformer or 20pF LT5525 VCC LOIN 50Ω 15 LO+ 480Ω 54Ω IF+ L3 11 T2 4:1 IFOUT 575Ω 20pF 0.7pF IF– C3 VCC L2 10 5525 F07 VCC 5525 F09 Figure 7. LO Input Schematic Figure 9. IF Output with External Matching 5525f 9 LT5525 U W U U APPLICATIO S I FOR ATIO through impedance-matching inductors. Each IF pin draws about 7.5mA of supply current (15mA total). For optimum single-ended performance, these differential outputs must be combined externally through an IF transformer or balun. An equivalent small-signal model for the output is shown in Figure 10. The output impedance can be modeled as a 574Ω resistor (RIF) in parallel with a 0.7pF capacitor. For most applications, the bond-wire inductance (0.7nH per side) can be ignored. The external components, C3, L2 and L3 form an impedance transformation network to match the mixer output impedance to the input impedance of transformer T2. The values for these components can be estimated using the equations below, along with the impedance values listed in Table 3. As an example, at an IF frequency of 140MHz and RL = 200Ω (using a 4:1 transformer for T2 with an external 50Ω load), n = RIF/RL = 574/200 = 2.87 Q = √(n – 1) = 1.368 XC = RIF/Q = 420Ω C = 1/(ω • XC) = 2.71pF C3 = C – CIF = 2.01pF XL = RL • Q = 274Ω L2 = L3 = XL/2ω = 156nH Table 3. IF Differential Impedance (Parallel Equivalent) FREQUENCY (MHz) 70 140 240 450 750 860 1000 1250 1500 OUTPUT IMPEDANCE 575|| – j3.39k 574|| – j1.67k 572|| – j977 561|| – j519 537|| – j309 525|| – j267 509|| – j229 474|| – j181 435|| – j147 REFLECTION COEFFICIENT MAG ANGLE 0.840 –1.8 0.840 –3.5 0.840 –5.9 0.838 –11.1 0.834 –18.6 0.831 –21.3 0.829 –24.8 0.822 –31.3 0.814 –38.0 LT5525 0.7nH RIF 574Ω IF+ L3 11 CIF 0.7pF RL 200Ω C3 0.7nH IF– L2 10 5525 F10 Figure 10. IF Output Small Signal Model element network. This circuit is shown in Figure 11, where L11, L12, C11 and C12 form a narrowband bridge balun. These element values are selected to realize a 180° phase shift at the desired IF frequency, and can be estimated using the equations below. In this case, the load resistance, RL, is 50Ω. RIF • RL ω 1 C11 = C12 = ω RIF • RL L11 = L12 = Inductor L13 or L14 provides a DC path between VCC and the IF+ pin. Only one of these inductors is required. Low cost multilayer chip inductors are adequate for L11, L12 and L13. If L14 is used instead of L13, a larger value is usually required, which may require the use of a wirewound inductor. Capacitor C13 is a DC block which can also be used to adjust the impedance match. Capacitor C14 is a bypass capacitor. IF+ C12 L11 C13 L14 OPT IFOUT 50Ω C11 IF– L12 L13 OPT C14 VCC 5525 F11 Low Cost Output Match For low cost applications in which the required fractional bandwidth of the IF output is less than 25%, it may be possible to replace the output transformer with a lumped- Figure 11. Narrowband Bridge IF Balun Actual component values for IF frequencies of 240MHz, 360MHz and 450MHz are listed in Table 4. Typical IF port return loss for these examples is shown in Figure 12. 5525f 10 LT5525 U W U U APPLICATIO S I FOR ATIO Conversion gain and IIP3 performance with an RF frequency of 1900MHz are plotted vs IF frequency in Figure 13. These results show that the usable IF bandwidth for the lumped element balun is greater than 60MHz, assuming tight tolerance matching components. Contact the factory for applications assistance with this circuit. 0 Table 4. Component Values for Lumped Balun IF FREQ (MHz) 240 360 450 L11, L12 (nH) C11, C12 (pF) C13 (pF) L14 (nH) 100 3.9 100 560 68 2.7 10 270 56 2.2 8.2 180 20 20 19 15 –10 –15 –20 17 250 300 350 400 FREQUENCY (MHz) 450 500 TA = 25°C fLO = fRF – fIF fRF = 1900MHz PLO = –5dBm PRF = –15dBm 10 5 GAIN –5 200 250 300 350 400 IF FREQUENCY (MHz) 5525 F12 Figure 12. Typical IF Return Loss Performance with 240MHz, 360MHz and 450MHz Lumped Element Baluns 16 15 14 13 0 –25 200 18 IIP3 (dBm) GAIN (dB), IIP3 (dBm) RETURN LOSS (dB) –5 IIP3 450 500 TA = 25°C 12 f = f – f LO RF IF 11 PLO = –5dBm PRF = –15dBm 10 1200 1400 1600 1800 2000 2200 RF FREQUENCY (MHz) 5525 F13 Figure 13. Typical Gain and IIP3 vs IF Frequency with 240MHz, 360MHz and 450MHz Lumped Element Baluns 240MHz 360MHz 450MHz 2400 2600 5525 F14 Figure 14. Typical IIP3 vs RF Frequency with Lumped Element Baluns and IF Frequencies of 240MHz, 360MHz and 450MHz U TYPICAL APPLICATIO S Evaluation Board Layouts Top Layer Silkscreen Top Layer Metal 5525f 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. 11 LT5525 U PACKAGE DESCRIPTIO UF Package 16-Lead Plastic QFN (4mm × 4mm) (Reference LTC DWG # 05-08-1692) 0.72 ±0.05 R = 0.115 TYP 0.75 ± 0.05 4.00 ± 0.10 (4 SIDES) 0.55 ± 0.20 15 16 PIN 1 TOP MARK (NOTE 6) 1 4.35 ± 0.05 2.15 ± 0.05 (4 SIDES) 2 2.15 ± 0.10 (4-SIDES) 2.90 ± 0.05 PACKAGE OUTLINE (UF) QFN 1103 0.200 REF 0.30 ±0.05 0.65 BSC 0.30 ± 0.05 0.00 – 0.05 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 0.65 BSC BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING CONFORMS TO JEDEC PACKAGE OUTLINE MO-220 VARIATION (WGGC) 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 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 RELATED PARTS PART NUMBER Infrastructure LT5512 LT5514 DESCRIPTION COMMENTS LT5519 DC-3GHz High Signal Level Down Converting Mixer Ultralow Distortion, IF Amplifier/ADC Driver with Digitally Controlled Gain 0.7GHz to 1.4GHz High Linearity Upconverting Mixer LT5520 1.3GHz to 2.3GHz High Linearity Upconverting Mixer LT5521 3.7GHz Very High Linearity Mixer LT5522 600MHz to 2.7GHz High Signal Level Downconverting Mixer LT5526 High Linearity, Low Power Downconverting Mixer 21dBm IIP3, Integrated LO Buffer 850MHz Bandwidth, 47dBm OIP3 at 100MHz, 10.5dB to 33dB Gain Control Range 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, 12.5dB SSBNF, –42dBm LO Leakage, Supply Voltage = 3.15V to 5.25V 4.5V to 5.25V Supply, 25dBm IIP3 at 900MHz, NF = 12.5dB, 50Ω Single-Ended RF and LO Ports 16.5dBm IIP3 at 900MHz, NF = 11dB, Supply Current = 28mA, 3.6V to 5.3V Supply RF Power Detectors LTC5508 300MHz to 7GHz RF Power Detector LTC5532 300MHz to 7GHz Precision RF Power Detector LT5534 50MHz to 3GHz RF Power Detector with 60dB Dynamic Range LTC5535 600MHz to 7GHz RF Power Detector Wide Bandwidth ADCs LTC1749 12-Bit, 80Msps ADC LTC1750 14-Bit, 80Msps ADC LTC2222/ LTC2223 LTC2224/ LTC2234 12-Bit, 105Msps/80Msps ADC 10-Bit/12-Bit, 135Msps ADC 44dB Dynamic Range, Temperature Compensated, SC70 Package Precision VOUT Offset Control, Adjustable Gain and Offset ±1dB Output Variation over Temperature, 38ns Response Time 12MHz Baseband BW, Precision Offset with Adjustable Gain and Offset 500MHz BW S/H, 71.8dB SNR, 87dB SFDR 500MHz BW S/H, 75.5dB SNR, 90dB SFDR, 2.25VP-P or 1.35VP-P Input Ranges Low Power 775MHz BW S/H, 61dB SNR, 75dB SFDR ±0.5V or ±1V Input Low Power 775MHz BW S/H, 61dB SNR, 75dB SFDR ±0.5V or ±1V Input 5525f 12 Linear Technology Corporation LT/TP 1004 1K • PRINTED IN THE USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2004