LT MHz to 3.8GHz 3.3V Active Downconverting Mixer. Features. Description. Applications. Typical Application

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1 LT7 MHz to.ghz.v Active Downconverting Mixer Features n Wide RF Frequency Range: MHz to.ghz* n High Input IP:. at MHz.7 at MHz.7 at.ghz n Conversion Gain:. at MHz. at MHz n LO Drive Level n Low LO Leakage n Low Noise Figure:. at MHz.7 at MHz n Low Power:.V/mW n Ω Single-Ended RF and LO Ports n Very Few External Components n -Lead (mm mm) QFN Package Applications n Cellular, CDMA, WCDMA, TD-SCDMA and UMTS Infrastructure n WiMAX n Wireless Infrastructure Receiver n Wireless Infrastructure PA Linearization n MHz/.GHz/.GHz WLAN Description The LT 7 active mixer is optimized for high linearity, wide dynamic range downconverter applications. The IC includes a high speed differential LO buffer amplifier driving a double-balanced mixer. Broadband, integrated transformers on the RF and LO inputs provide single-ended Ω interfaces. The differential IF output allows convenient interfacing to differential IF filters and amplifiers, or is easily matched to drive a single-ended Ω load, with or without an external transformer. The RF input is internally matched to Ω from.ghz to.ghz, and the LO input is internally matched to Ω from GHz to GHz. The frequency range of both ports is easily extended with simple external matching. The IF output is partially matched and usable for IF frequencies up to MHz. The LT7 s high level of integration minimizes the total solution cost, board space and system-level variation. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.\*operation over a wider frequency range is possible with reduced performance. Consult factory for information and assistance. Typical Application High Signal Level Downmixer for Multi-Carrier Wireless Infrastructure RF INPUT LT7 RF LO INPUT (TYP) BIAS EN V CC V CC IF + IF nh nh nh.7pf nf µf.7pf 7 TAa nf.v IF OUTPUT MHz (), NF (), () Conversion Gain,, and LO Leakage vs RF Frequency 7 IF = MHz P LO = TA = C V CC =.V LO-IF LO-RF RF FREQUEY (MHz) 7 TAb LO LEAKAGE ()

2 LT7 Absolute Maximum Ratings (Note ) Supply Voltage (V CC, V CC, IF +, IF )...V Enable Voltage....V to V CC +.V LO Input Power (MHz to.ghz)... + LO Input DC Voltage... V to V CC + V RF Input Power (MHz to.ghz)... + Continuous RF Input Power (MHz to.ghz)... + RF Input DC Voltage... ±.V Operating Temperature Range... C to C Storage Temperature Range... C to C Junction Temperature (T J )... C Pin Configuration TOP VIEW LO IF + 7 RF IF 7 EN VCC VCC UF PACKAGE -LEAD (mm mm) PLASTIC QFN T JMAX = C, θ JC = C/W, θ JA = 7 C/W EXPOSED PAD (PIN 7) IS, MUST BE SOLDERED TO PCB CAUTION: This part is sensitive to electrostatic discharge (ESD). It is very important that proper ESD precautions be observed when handling the LT7. Order Information LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LT7EUF#PBF LT7EUF#TRPBF 7 -Lead (mm mm) Plastic QFN C to 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: For more information on tape and reel specifications, go to: DC Electrical Characteristics V CC =.V, EN = High, T A = C, unless otherwise specified. Test circuit shown in Figure. (Note ) PARAMETER CONDITIONS MIN TYP MAX UNITS Power Supply Requirements (V CC ) Supply Voltage... V Supply Current V CC (Pin 7) V CC (Pin ) IF + + IF (Pin + Pin ) Total Supply Current Enable (EN) Low = Off, High = On Shutdown Current EN = Low µa Input High Voltage (On).7 V Input Low Voltage (Off). V EN Pin Input Current EN =.V DC µa Turn-ON Time. µs Turn-OFF Time. µs AC Electrical Characteristics Test circuit shown in Figure. (Notes, ) PARAMETER CONDITIONS MIN TYP MAX UNITS RF Input Frequency Range No External Matching (Midband) to MHz With External Matching (Low Band or High Band) MHz LO Input Frequency Range No External Matching to MHz With External Matching MHz IF Output Frequency Range Requires Appropriate IF Matching. to MHz RF Input Return Loss Z O = Ω, MHz to MHz (No External Matching) >.... ma ma ma ma

3 Ac electrical characteristics Test circuit shown in Figure. (Notes, ) LT7 PARAMETER CONDITIONS MIN TYP MAX UNITS LO Input Return Loss Z O = Ω, MHz to MHz (No External Matching) > IF Output Impedance Differential at MHz Ω.pF R C LO Input Power MHz to MHz MHz to MHz Standard Downmixer Application: V CC =.V, EN = High, T A = C, P RF = ( /tone for -tone tests, f = MHz), f LO = f RF f IF, P LO = ( for MHz and MHz tests), IF output measured at MHz, unless otherwise noted. Test circuit shown in Figure. (Notes,, ) PARAMETER CONDITIONS MIN TYP MAX UNITS Conversion Gain Note : 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 : MHz and MHz performance measured with external LO and RF matching. MHz and MHz performance measured with external RF matching. See Figure and Applications Information. RF = MHz, IF = 7MHz, High Side LO RF = MHz, IF = MHz RF = 7MHz RF = MHz RF = MHz RF = MHz, IF = MHz RF = MHz, IF = MHz Conversion Gain vs Temperature T A = C to C, RF = MHz.7 / C Input rd Order Intercept RF = MHz, IF = 7MHz, High Side LO RF = MHz, IF = MHz RF = 7MHz RF = MHz RF = MHz RF = MHz, IF = MHz RF = MHz, IF = MHz Single-Sideband Noise Figure LO to RF Leakage LO to IF Leakage RF to LO Isolation RF to IF Isolation RF-LO Output Spurious Product (f RF = f LO + f IF /) RF-LO Output Spurious Product (f RF = f LO + f IF /) Input Compression RF = MHz, IF = 7MHz, High Side LO RF = MHz, IF = MHz RF = 7MHz RF = MHz RF = MHz RF = MHz, IF = MHz RF = MHz, IF = MHz f LO = MHz to MHz f LO = MHz to MHz f LO = MHz to MHz f LO = MHz to MHz f RF = MHz to 7MHz f RF = 7MHz to MHz f RF = MHz to MHz f RF = MHz to MHz MHz: f RF = MHz at, f IF = MHz MHz: f RF = MHz at, f IF = MHz MHz: f RF =.7MHz at, f IF = MHz MHz: f RF = 7MHz at, f IF = MHz RF = MHz, IF = 7MHz, High Side LO RF = MHz, IF = MHz RF = MHz RF = MHz, IF = MHz RF = MHz, IF = MHz > > > > Note : The LT7 is guaranteed functional over the C to C operating temperature range. Note : SSB Noise Figure measurements performed with a small-signal noise source and bandpass filter on RF input, and no other RF signal applied. c c c c

4 LT7 Typical Performance Characteristics V CC =.V, Test circuit shown in Figure. Midband (no external RF/LO matching) MHz IF output, P RF = ( /tone for -tone tests, f = MHz), P LO =, unless otherwise noted. (), NF (), () Conversion Gain, and NF vs RF Frequency HIGH SIDE LO T A = C IF = MHz RF FREQUEY (GHz) LO LEAKAGE (). LO Leakage and RF Isolation vs LO and RF Frequency LO-IF RF-LO RF-IF LO-RF T A = C P LO = LO/RF FREQUEY (GHz) RF ISOLATION () SUPPLY CURRENT (ma) Supply Current vs Supply Voltage C C C C C SUPPLY VOLTAGE (V) 7 G 7 G 7 G (), () Conversion Gain and vs Temperature (Low Side LO) 7MHz MHz MHz IF = MHz 7 TEMPERATURE ( C) (), () Conversion Gain and vs Temperature (High Side LO) 7MHz MHz MHz IF = MHz 7 TEMPERATURE ( C) (), NF (), (). MHz Conversion Gain, and NF vs Supply Voltage C C C IF = MHz SUPPLY VOLTAGE (V) 7 G 7 G 7 G (), NF (), () MHz Conversion Gain, and NF vs LO Power C C C IF = MHz 7 LO INPUT POWER () (), NF (), () MHz Conversion Gain, and NF vs LO Power C C C IF = MHz 7 LO INPUT POWER () (), NF (), () MHz Conversion Gain, and NF vs LO Power C C C IF = MHz 7 LO INPUT POWER () 7 G7 7 G 7 G

5 Typical Performance Characteristics IF Output Power, IM and IM vs RF Input Power ( Input Tones) IF OUT, and Spurs vs RF Input Power (Single Tone) and Spurs vs LO Power (Single Tone) LT7 V CC =.V, Test circuit shown in Figure. Midband (no external RF/LO matching) MHz IF output, P RF = ( /tone for -tone tests, f = MHz), P LO =, unless otherwise noted. OUTPUT POWER/TONE () 7 IF OUT IM T A = C RF =.MHz RF =.MHz LO = 7MHz IM RF INPUT POWER (/TONE) 7 G OUTPUT POWER () IF OUT (RF = MHz) T A = C LO = 7MHz IF = MHz RF-LO (RF = MHz) 7 RF-LO (RF = 7MHz) RF INPUT POWER () 7 G RELATIVE SPUR LEVEL (c) 7 7 RF-LO (RF = MHz) RF-LO (RF = 7MHz) T A = C LO = 7MHz IF = MHz P RF = 7 LO INPUT POWER () 7 G DISTRIBUTION (%) Conversion Gain Distribution at MHz T A = C IF = MHz DISTRIBUTION (%) Distribution at MHz C C C IF = MHz DISTRIBUTION (%) 7 SSB Noise Figure Distribution at MHz T A = C IF = MHz CONVERSION GAIN (). 7 G () 7 7 G SSB NOISE FIGURE () 7 G7 MHz application (with external RF/LO matching) 7MHz IF output, P RF = ( /tone for -tone tests, f = MHz), high side LO at, unless otherwise noted. (), NF (), () Conversion Gain, and NF vs RF Frequency HIGH SIDE LO T A = C IF = 7MHz 7 RF FREQUEY (MHz) 7 G (), NF (), () 7 7 MHz Conversion Gain, and NF vs LO Power C C C HIGH SIDE LO IF = 7MHz LO INPUT POWER () 7 G LO LEAKAGE () LO Leakage vs LO Frequency MHz and MHz Applications T A = C P LO = MHz APPLICATION LO FREQUEY (MHz) LO-RF LO-IF MHz APPLICATION 7 G

6 LT7 Typical Performance Characteristics V CC =.V, Test circuit shown in Figure. MHz application (with external RF/LO matching), MHz IF output, P RF = ( /tone for -tone tests, f = MHz), low side LO at, unless otherwise noted. (), NF (), () Conversion Gain, and NF vs RF Frequency T A = C IF = MHz 7 RF FREQUEY (MHz) Conversion Gain, and SSB NF vs RF Frequency Conversion Gain, and SSB NF vs RF Frequency 7 G (), NF (), () MHz Conversion Gain, and NF vs LO Power LO INPUT POWER () IF = MHz.GHz Conversion Gain, and NF vs LO Power.GHz Conversion Gain, and vs LO Power IF OUT, and Spurs vs RF Input Power (Single Tone).GHz to.7ghz application (with external RF matching) MHz IF output, P RF = ( /tone for -tone tests, f = MHz), P LO =, unless otherwise noted. (), NF (), (). HIGH SIDE LO T A = C....7 RF FREQUEY (GHz) 7 G (), NF (), () LO Leakage and RF Isolation vs LO and RF Frequency.GHz to.ghz application (with external RF matching) MHz IF output, P RF = ( /tone for -tone tests, f = MHz), low side LO at, unless otherwise noted. (), NF (), () T A = C RF FREQUEY (GHz) 7 G (), NF (), () C C C 7 G7 C C C 7 LO INPUT POWER () 7 G C C C 7 LO INPUT POWER () 7 G LO LEAKAGE () LO LEAKAGE () OUTPUT POWER (). 7. IF T A = C OUT (RF = MHz) LO = 7MHz IF = MHz RF-LO (RF = MHz) 7 RF-LO (RF =.7MHz) RF INPUT POWER () LO-RF LO-IF RF-LO RF-IF LO Leakage and RF Isolation vs LO and RF Frequency 7 G LO/RF FREQUEY (GHz) LO-IF LO-RF RF-LO RF-IF 7 G RF ISOLATION () RF ISOLATION ()..... LO/RF FREQUEY (GHz) 7 G

7 Pin Functions (Pins,,,,,, ): Not Connected Internally. These pins should be grounded on the circuit board for the best LO-to-RF and LO-to-IF isolation. RF (Pin ): Single-Ended Input for the RF Signal. This pin is internally connected to the primary side of the RF input transformer, which has low DC resistance to ground. If the RF source is not DC blocked, then a series blocking capacitor must be used. The RF input is internally matched from.ghz to.ghz. Operation down to MHz or up to.ghz is possible with simple external matching. EN (Pin ): Enable Pin. When the input enable voltage is higher than.7v, the mixer circuits supplied through Pins, 7, and are enabled. When the input voltage is less than.v, all circuits are disabled. Typical input current is µa for EN =.V and µa when EN = V. The EN pin should not be left floating. Under no conditions should the EN pin voltage exceed V CC +.V, even at start-up. V CC (Pin ): Power Supply Pin for the Bias Circuits. Typical current consumption is.ma. This pin should be externally connected to the V CC pin and decoupled with pf and µf capacitors. V CC (Pin 7): Power Supply Pin for the LO Buffer Circuits. Typical current consumption is.ma. This pin should LT7 be externally connected to the V CC pin and decoupled with pf and µf capacitors. (Pins, ): Ground. These pins are internally connected to the backside ground for improved isolation. They should be connected to the RF ground on the circuit board, although they are not intended to replace the primary grounding through the backside contact of the package. IF, IF + (Pins, ): Differential Outputs for the IF Signal. An impedance transformation may be required to match the outputs. These pins must be connected to V CC through impedance matching inductors, RF chokes or a transformer center tap. Typical current consumption is.ma each (.ma total). LO (Pin ): Single-Ended Input for the Local Oscillator Signal. This pin is internally connected to the primary side of the LO transformer, which is internally DC blocked. An external blocking capacitor is not required. The LO input is internally matched from GHz to GHz. Operation down to MHz is possible with simple external matching. Exposed Pad (Pin 7): Circuit Ground Return for the Entire IC. This must be soldered to the printed circuit board ground plane. Block Diagram LO REGULATOR V REF LIMITING AMPLIFIERS V CC EXPOSED PAD 7 IF + RF DOUBLE-BALAED MIXER IF BIAS EN V CC V CC 7 7 BD 7

8 LT7 Test Circuits EXTERNAL MATCHING FOR LO BELOW GHz LO IN RF IN LOWPASS MATCH FOR MHz, MHz AND.GHz RF RF IN C L Z O Ω L (mm) C C.pF LO LT7 RF EN V CC V CC 7 EN C IF + IF C." L."." ε R =.7 T RF BIAS V CC (.V to.v) C DCA BOARD STACK-UP (NELCO N-) IF OUT MHz *HIGHPASS MATCH FOR.GHz RF L.nH 7 F APPLICATION RF MATCH LO MATCH IF MATCH RF LO IF L C L C L C MHz High Side 7MHz.mm pf nh.pf 7nH pf MHz Low Side MHz.7mm.pF.7nH.pF nh.pf.ghz MHz HIGHPASS* 7nH.pF.GHz MHz.mm pf nh REF DES VALUE SIZE PART NUMBER REF DES VALUE SIZE PART NUMBER C pf AVX CJAT L, C, C See Applications Information C µf AVX ZDKAT L nh Toko LLQ-FNG C.pF AVX ARBAT T : Mini-Circuits TC-+ Figure. Standard Downmixer Test Schematic Transformer-Based Bandpass IF Matching (MHz IF) EXTERNAL MATCHING FOR LO BELOW GHz LOWPASS MATCH FOR MHz, MHz AND.GHz RF LO IN RF IN C L Z O Ω L (mm) C EN LO LT7 RF EN V CC V CC 7 C IF + IF L DISCRETE IF BALUN L C L C7 C V CC (.V to.v) C."."." IF OUT MHz ε R =. RF BIAS DCA BOARD STACK-UP (FR-) 7 F REF DES VALUE SIZE PART NUMBER REF DES VALUE SIZE PART NUMBER C, C pf AVX CJAT L, C, C See Applications Information C µf AVX ZDKAT L, L nh Toko LL-FSLRJ C, C7.7pF AVX AR7CAT L nh Toko LL-FSLRJ Figure. Downmixer Test Schematic Discrete IF Balun Matching (MHz IF)

9 Applications Information Introduction The LT7 consists of a high linearity double-balanced mixer, RF buffer amplifier, high speed limiting LO buffer amplifier and bias/enable circuits. The RF and LO inputs are both single ended. The IF output is differential. Low side or high side LO injection can be used. Two evaluation circuits are available. The standard evaluation circuit, shown in Figure, incorporates transformerbased IF matching and is intended for applications that require the highest dynamic range and the widest IF bandwidth. The second evaluation circuit, shown in Figure, replaces the IF transformer with a discrete IF balun for reduced solution cost and size. The discrete IF balun delivers higher conversion gain, but slightly degraded and noise figure, and reduced IF bandwidth. RF Input Port The mixer s RF input, shown in Figure, consists of an integrated transformer and a high linearity differential amplifier. The primary terminals of the transformer are connected to the RF input (Pin ) and ground. The secondary side of the transformer is internally connected to the amplifier s differential inputs. The DC resistance of the primary is.ω. If the RF source has DC voltage present, then a coupling capacitor must be used in series with the RF input pin. The RF input is internally matched from.ghz to.ghz, requiring no external components over this frequency range. The input return loss, shown in Figure a, is typically at the band edges. The input match at the lower RF IN RF IN LOWPASS MATCH FOR MHz, MHz and.ghz RF Z O = Ω L = L (mm) L C C RF HIGHPASS MATCH FOR.GHz RF AND WIDEBAND RF Figure. RF Input Schematic TO MIXER 7 F LT7 band edge can be optimized with a series.pf capacitor at Pin, which improves the.ghz return loss to greater than. Likewise, the.ghz match can be improved to greater than with a series.nh inductor. A series.7nh/.pf network will simultaneously optimize the lower and upper band edges and expand the RF input bandwidth to.ghz-.ghz. Measured RF input return losses for these three cases are also plotted in Figure a. Alternatively, the input match can be shifted as low as MHz or up to MHz by adding a shunt capacitor (C) to the RF input. A MHz input match is realized with C = pf, located.mm away from Pin on the evaluation board s Ω input transmission line. A MHz input match requires C =.pf, located at.7mm. A.GHz input match is realized with C = pf, located at.mm. RF PORT RETURN LOSS () RF PORT RETURN LOSS ().. SERIES.pF NO EXT MATCH SERIES.7nH AND.pF SERIES.nH FREQUEY (GHz) 7 Fa (a) Series Reactance Matching MHz L =.mm C = pf MHz L =.7mm C =.pf NO EXT MATCH FREQUEY (GHz) 7 Fb (b) Series Shunt Matching Figure. RF Input Return Loss with and without External Matching.GHz L =.mm C = pf.ghz SERIES.pF SHUNT.nH

10 LT7 applications information This series transmission line/shunt capacitor matching topology allows the LT7 to be used for multiple frequency standards without circuit board layout modifications. The series transmission line can also be replaced with a series chip inductor for a more compact layout. Input return losses for the MHz, MHz,.GHz and.ghz applications are plotted in Figure b. The input return loss with no external matching is repeated in Figure b for comparison. The.GHz RF input match uses the highpass matching network shown in Figures and with C =.pf and L =.nh. The highpass input matching network is also used to create a wideband or dual-band input match. For example, with C =.pf and L = nh, the RF input is matched from MHz to.ghz, with optimum matching in the MHz to.ghz and.ghz to.ghz bands, simultaneously. RF input impedance and S versus frequency (with no external matching) are listed in Table and referenced to Pin. The S data can be used with a microwave circuit simulator to design custom matching networks and simulate board level interfacing to the RF input filter. Table. RF Input Impedance vs Frequency FREQUEY INPUT S (MHz) IMPEDAE MAG ANGLE. + j j j j j j j j.... j.... j j..7.. j.... j j j..7. LO Input Port The mixer s LO input, shown in Figure, consists of an integrated transformer and high speed limiting differential amplifiers. The amplifiers are designed to precisely drive the mixer for the highest linearity and the lowest noise figure. An internal DC blocking capacitor in series with the transformer s primary eliminates the need for an external blocking capacitor. The LO input is internally matched from GHz to GHz. The input match can be shifted down, as low as 7MHz, with a single shunt capacitor (C) on Pin. One example is plotted in Figure where C =.7pF produces a 7MHz to GHz match. LO input matching below 7MHz requires the series inductor (L)/shunt capacitor (C) network shown in Figure. Two examples are plotted in Figure, where L =.7nH/C =.pf produces a MHz to MHz match and L = nh/c =.pf produces a MHz to MHz match. The evaluation boards do not include pads for L, so the circuit trace needs to be cut near Pin to insert L. A low cost multilayer chip inductor is adequate for L. LO IN EXTERNAL MATCHING FOR LO < GHz C L LO PORT RETURN LOSS () LO V CC REGULATOR Figure. LO Input Schematic L = nh C =.pf L =.7nH C =.pf. NO EXT MATCH L = C =.7pF LIMITER V REF TO MIXER 7 F LO FREQUEY (GHz) 7 G Figure. LO Input Return Loss

11 LT7 Applications Information The optimum LO drive is for LO frequencies above.ghz, although the amplifiers are designed to accommodate several of LO input power variation without significant mixer performance variation. Below.GHz, LO drive is recommended for optimum noise figure, although will still deliver good conversion gain and linearity. Custom matching networks can be designed using the port impedance data listed in Table. This data is referenced to the LO pin with no external matching. Table. LO Input Impedance vs Frequency FREQUEY INPUT S (MHz) IMPEDAE MAG ANGLE. j. 7.. j.... j j j j j.... j j j j.7... j j....7 j j..7. IF Output Port The IF outputs, IF + and IF, are internally connected to the collectors of the mixer switching transistors (see Figure 7). Both pins must be biased at the supply voltage, which can be applied through the center tap of a transformer or through matching inductors. Each IF pin draws.ma of supply current (.ma total). For optimum singleended performance, these differential outputs should be combined externally through an IF transformer or a discrete IF balun circuit. The standard evaluation board (see Figure ) includes an IF transformer for impedance transformation and differential to single-ended transformation. A second evaluation board (see Figure ) realizes the same functionality with a discrete IF balun circuit. The IF output impedance can be modeled as Ω in parallel with.pf at low frequencies. An equivalent smallsignal model (including bondwire inductance) is shown in Figure. Frequency-dependent differential IF output impedance is listed in Table. This data is referenced to the package pins (with no external components) and includes the effects of IC and package parasitics. The IF output can be matched for IF frequencies as low as several khz or as high as MHz. Table. IF Output Impedance vs Frequency DIFFERENTIAL OUTPUT FREQUEY (MHz) IMPEDAE (R IF X IF ) j.7k (.pf) 7 j7 (.pf) j (.pf) j (.pf) j (.pf) j (.pf) j (.7pF) j (.pf) j (.pf) Two methods of differential to single-ended IF matching are described: Transformer-based bandpass Discrete IF balun V CC IF + IF 7 F7 L V CC Figure 7. IF Output with External Matching.7nH IF + Figure. IF Output Small-Signal Model C R S C S R IF X IF IF.7nH 7 F : IF OUT Ω

12 LT7 applications information Transformer-Based Bandpass IF Matching The standard evaluation board (shown in Figure ) uses an L-C bandpass IF matching network, with an : transformer connected across the IF pins. The L-C network maximizes mixer performance at the desired IF frequency. The transformer performs impedance transformation and provides a single-ended Ω output. The value of L is calculated as: L = /[(πf IF ) C IF ] where C IF is the sum of C and the internal IF capacitance (listed in Table ). The value of C is selected such that L falls on a standard value, while satisfying the desired IF bandwidth. The IF bandwidth can be estimated as: BW IF = /(πr EFF C IF ) where R EFF, the effective IF resistance when loaded with the transformer and inductor loss, is approximately Ω. Below MHz, the magnitude of the internal IF reactance is relatively high compared to the internal resistance. In this case, L (and C) can be eliminated, and the : transformer alone is adequate for IF matching. The LT7 was characterized with IF frequencies of 7MHz, MHz, MHz, MHz and MHz. The values of L and C used for these frequencies are tabulated in Figure and repeated in Figure. In all cases, L is a high-q wire-wound chip inductor, for highest conversion gain. Low cost multilayer chip inductors can be substituted, with a slight reduction in conversion gain. The measured IF output return losses are plotted in Figure. IF PORT RETURN LOSS ( A C D E IF FREQUEY (MHz) A: 7MHz, L = 7nH, C = pf B: MHz, L = nh, C =.pf C: MHz, L = nh, C =.pf D: MHz, L = 7nH, C =.pf E: MHz, L = nh, C = pf Figure. IF Output Return Loss with Transformer-Based Bandpass Matching Discrete IF Balun Matching For many applications, it is possible to replace the IF transformer with the discrete IF balun shown in Figure. The values of L, L, C and C7 are calculated to realize a degree phase shift at the desired IF frequency and provide a Ω single-ended output, using the following equations. Inductor L is calculated to cancel the internal.pf capacitance. L also supplies bias voltage to the IF + pin. Low cost multilayer chip inductors are adequate for L, L and L. C is a DC blocking capacitor. L, L= R IF R OUT ω IF C,C7 = ω IF R IF R OUT B 7 G L= X IF ω IF

13 Applications Information These equations give a good starting point, but it is usually necessary to adjust the component values after building and testing the circuit. The final solution can be achieved with less iteration by considering the parasitics of L in the above calculations. Specifically, the effective parallel resistance of L (calculated from the manufacturer s Q data) will reduce the value of R IF, which in turn influences the calculated values of L (= L) and C (= C7). Also, the effective parallel capacitance of L (taken from the manufacturers SRF data) must be considered, since it is in parallel with X IF (from Table ). Frequently, the calculated value for L does not fall on a standard value for the desired IF. In this case, a simple solution is to load the IF output with a high value external chip resistor in parallel with L, which reduces the value of R IF, until L is a standard value. Discrete IF balun element values for four common IF frequencies (MHz, MHz, MHz and MHz) are listed in Table. The MHz application circuit uses a.k resistor in parallel with L as previously described. The corresponding measured IF output return losses are shown in Figure. Typical conversion gain, and LO-IF leakage, versus RF input frequency for all four examples is shown in Figure. Typical conversion gain, and noise figure versus IF output frequency is shown in Figure. Compared to the transformer-based IF matching technique, this network delivers approximately higher conversion gain (since the IF transformer loss is eliminated), though noise figure and are degraded slightly. The most significant performance difference, as shown in Figure, is the limited IF bandwidth available from the discrete approach. For low IF frequencies, the absolute bandwidth is small, whereas higher IF frequencies offer wider bandwidth. Table. Discrete IF Balun Element Values (R OUT = Ω) IF FREQUEY (MHz) L, L C, C7 L nh.pf 7nH.kΩ nh.7pf nh nh.pf nh 7nH.pF 7nH Differential IF Output Matching IF PORT RETURN LOSS () MHz MHz MHz MHz IF FREQUEY (MHz) LT7 7 F Figure. IF Output Return Losses with Discrete Balun Matching (), () 7 IF IF IF IF ( ) T A = C LO-IF Figure. Conversion Gain, and LO-IF Leakage vs RF Input Frequency and IF Output Frequency (in MHz) Using Discrete IF Balun Matching (), NF (), () Figure. Conversion Gain, and vs IF Output Frequency Using Discrete IF Balun Matching 7 RF INPUT FREQUEY (MHz) 7 F IF IF IF IF RF = MHz ( ) T A = C IF OUTPUT FREQUEY (MHz) 7 F LO-IF LEAKAGE ()

14 LT7 applications information For fully differential IF architectures, the mixer s IF outputs can be matched directly into a SAW filter or IF amplifier, thus eliminating the IF transformer. One example is shown in Figure, where the mixer s Ω differential output resistance is matched into a Ω differential SAW filter using the tapped-capacitor technique. Inductors L and L form the inductive portion of the matching network, cancel the internal.pf capacitance, and supply DC bias current to the mixer core. Capacitors C through C are the capacitive portion of the matching, and perform the impedance step-down. The calculations for tapped-capacitor matching are cov- C Enable Interface Figure shows a simplified schematic of the EN pin interface. The voltage necessary to turn on the LT7 is.7v. To disable the chip, the enable voltage must be less than.v. If the EN pin is allowed to float, the chip will tend to remain in its last operating state. Thus, it is not recommended that the enable function be used in this manner. If the shutdown function is not required, then the EN pin should be connected directly to V CC. The voltage at the EN pin should never exceed the power supply voltage (V CC ) by more than.v. If this should occur, the supply current could be sourced through the EN pin ESD diode, potentially damaging the IC. IF + L C SAW FILTER IF AMP V CC LT7 IF L C7 7 F EN k SUPPLY DECOUPLING C V CC C C Figure. Differential IF Matching Using the Tapped-Capacitor Technique ered in the literature, and are not repeated here. Other differential matching options include lowpass, highpass and bandpass. The choice depends on the system performance goals, IF frequency, IF bandwidth and filter (or amplifier) input impedance. Contact the factory for applications assistance. 7 F Figure. Enable Input Circuit

15 applications information LT7 Figure. Standard Evaluation Board Layout (DCA) Figure. Discrete IF Evaluation Board Layout (DCA)

16 LT7 Package Description UF Package -Lead Plastic QFN (mm mm) (Reference LTC DWG # --).7 ±. PIN TOP MARK (NOTE ). ±. ( SIDES) BOTTOM VIEW EXPOSED PAD.7 ±. R =. TYP PIN NOTCH R =. TYP OR. CHAMFER. ±.. ±.. ±. ( SIDES). ±.. ±. (-SIDES) PACKAGE OUTLINE. ±.. BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS. REF.. (UF) QFN -. ±.. BSC NOTE:. DRAWINONFORMS TO JEDEC PACKAGE OUTLINE MO- VARIATION (WGGC). DRAWING NOT TO SCALE. ALL DIMENSIONS ARE IN MILLIMETERS. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT ILUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED.mm ON ANY SIDE. EXPOSED PAD SHALL BE SOLDER PLATED. SHADED AREA IS ONLY A REFEREE FOR PIN LOCATION ON THE TOP AND BOTTOM OF PACKAGE

17 LT7 Revision History (Revision history begins at Rev C) REV DATE DESCRIPTION PAGE NUMBER C / Revised title and Features Revised Absolute Maximum Ratings, Pin Configuration, DC Electrical Characteristics, AC Electrical Characteristics, and Note Updated Related Parts list, 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. 7

18 LT7 Related Parts PART NUMBER DESCRIPTION COMMENTS Infrastructure LT khz to GHz High Signal Level Active Mixer from MHz to MHz, Integrated LO Buffer, HF/VHF/UHF Optimized LT Ultralow Distortion, IF Amplifier/ADC Driver MHz Bandwidth, 7 OIP at MHz,. to Gain Control Range with Digitally Controlled Gain LT.GHz to.ghz Direct Conversion Quadrature, Integrated LO Quadrature Generator Demodulator LT.GHz to.ghz Direct Conversion Quadrature., Integrated LO Quadrature Generator Demodulator LT7 MHz to MHz Quadrature Demodulator, Integrated LO Quadrature Generator LT.7GHz to.ghz High Linearity Upconverting Mixer 7. at GHz, Integrated RF Output Transformer with Ω Matching, Single-Ended LO and RF Ports Operation LT.GHz to.ghz High Linearity Upconverting Mixer. at.ghz, Integrated RF Output Transformer with Ω Matching, Single-Ended LO and RF Ports Operation LT MHz to 7MHz High Linearity Upconverting Mixer. at.ghz, NF =.,.V to.v Supply, Single-Ended LO Port Operation LT MHz to.7ghz High Signal Level Downconverting Mixer.V to.v Supply, at MHz, NF =., Ω Single-Ended RF and LO Ports LT High Linearity, Low Power Downconverting Mixer Single-Ended Ω RF and LO Ports, 7. at MHz, I CC = ma LT High Linearity, Low Power Downconverting Mixer V to.v Supply,., khz to GHz RF, NF =, I CC = ma, LO-RF Leakage LT7 MHz to.7ghz, V High Signal Level. at.ghz, NF =., Single-Ended RF and LO Ports Downconverting Mixer LT.GHz to.ghz High Linearity Direct I/Q. OIP at GHz, /Hz Noise Floor, Ω Interface at All Ports Modulator LT MHz to.ghz High Linearity Direct I/Q Modulator. OIP,./Hz Noise Floor, c Image Rejection, Carrier Leakage LTC MHz to GHz.V Dual Active Gain,.,.7 NF at MHz Downconverting Mixer RF Power Detectors LTC RF Peak Detectors with > Dynamic Range MHz to GHz, Temperature Compensated, to LTC7 khz to MHz RF Peak Power Detector khz to GHz, Temperature Compensated, to LTC MHz to 7GHz RF Peak Power Detector Dynamic Range, Temperature Compensated, SC7 Package, to LTC MHz to GHz RF Peak Power Detector Dynamic Range, Low Power Consumption, SC7 Package, to LTC MHz to 7GHz Precision RF Peak Power Detector Precision V OUT Offset Control, Shutdown, Adjustable Gain, to LTC MHz to 7GHz Precision RF Peak Power Detector Precision V OUT Offset Control, Shutdown, Adjustable Offset, to LTC MHz to 7GHz Precision RF Peak Power Detector Precision V OUT Offset Control, Adjustable Gain and Offset, ±mv Offset Voltage Tolerence LTC MHz to GHz Dual Precision RF Peak Detector to, Adjustable Offset, Channel-to-Channel Isolation LT MHz to GHz RF Log Detector with Dynamic Range ± Output Variation Over Temperature, ns Response Time LTC Precision MHz to 7GHz RF Peak Detector with Fast Comparator Output ns Response Time, Comparator Reference Input, Latch Enable Input, to + Input Range LT7 Dynamic Range RF Log Detector LF to GHz, 7 to, Very Low Tempco Low Voltage RF Building Block LT MHz Quadrature Demodulator with VGA and 7MHz Baseband Bandwidth 7MHz Baseband Bandwidth, MHz to MHz IF,.V to.v Supply, 7 to Linear Power Gain LT REV C PRINTED IN USA Linear Technology Corporation McCarthy Blvd., Milpitas, CA -77 () - FAX: () -7 LINEAR TECHNOLOGY CORPORATION