Features n Conversion Gain:.dB at MHz n :.dbm at MHz n Noise Figure:.3dB at MHz n High Input P1dB n IF Bandwidth Up to 1GHz n mw Power Consumption n Shutdown Pin n Ω Single-Ended RF and Inputs n +dbm Drive Level n High -RF and -IF Isolation n C to C Operation (T C ) n Small Solution Size n -Lead (mm mm) QFN package Applications n GHz WiMAX/WLAN Receiver n.ghz Public Safety Bands n.ghz to GHz Military Communications n Point-to-Point Broadband Communications n Radar Systems 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. LTC GHz to GHz High Dynamic Range Downconverting Mixer Description The LTC is part of a family of high dynamic range, high gain passive downconverting mixers covering the MHz to GHz frequency range. The LTC is optimized for GHz to GHz RF applications. The frequency must fall within the.ghz to.8ghz range for optimum performance. A typical application is a WiMAX receiver with a.1ghz to.3ghz RF input and low side. The LTC is designed for 3.3V operation, however; the IF amplifier can be powered with V for the higher P1dB. The LTC s high level of integration minimizes the total solution cost, board space and system-level variation, while providing the highest dynamic range for demanding receiver applications. High Dynamic Range Downconverting Mixer Family PART# RF RANGE RANGE LTC MHz to 1.3GHz MHz to 1.GHz LTC1 1.3GHz to.3ghz 1.GHz to.ghz LTC 1.GHz to.ghz 1.GHz to.ghz LTC3.3GHz to GHz.GHz to 3.GHz LTC GHz to GHz.GHz to.8ghz Typical Application RF 1MHz TO 3MHz V CCIF 3.3V or V LNA 1µF IMAGE BPF.pF (V/3.3V) pf.nh V CC 3.3V Wideband Receiver 1nH RF 1nF 1nF 1nH IF + IF V CC1 1µF IF BIAS pf LTC V CC MHz SAW LTC IF AMP 1.pF LTC8 ADC SYNTH MHz (db) 8. 8.3 8.1....3.1... Wideband Conversion Gain, and NF vs IF Output Frequency f = MHz P = dbm RF = ±3MHz TEST CIRCUIT IN FIGURE 1 NF 3 1 1 1 1 1 3 IF OUTPUT FREQUENCY (MHz) TA1b (dbm), SSB NF (db) TA1a f 1
LTC Absolute Maximum Ratings (Note 1) Mixer Supply Voltage (V CC1, V CC )...V IF Supply Voltage (IF +, IF )...V Shutdown Voltage ()....3V to V CC +.3V IF Bias Adjust Voltage (IFBIAS)....3V to V CC +.3V Bias Adjust Voltage (BIAS)....3V to V CC +.3V Input Power (GHz to GHz)...+dBm Input DC Voltage... ±.1V RF Input Power (GHz to GHz)... +1dBm RF Input DC Voltage... ±.1V TEMP Diode Continuous DC Input Current...mA TEMP Diode Input Voltage... ±1V Operating Temperature Range (T C )... C to C Storage Temperature Range... C to 1 C Junction Temperature (T J )... 1 C Pin Configuration RF CT 1 3 TOP VIEW IFBIAS IF + IF IF 1 1 8 V CC1 BIAS VCC UF PACKAGE -LEAD (mm mm) PLASTIC QFN TEMP T JMAX = 1 C, θ JC = 8 C/W EXPOSED PAD (PIN 1) IS, MUST BE SOLDERED TO PCB Order Information LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION CASE TEMPERATURE RANGE LTCIUF#PBF LTCIUF#TRPBF -Lead (mm x 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: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ AC Electrical Characteristics V CC = 3.3V, V CCIF = 3.3V, = Low, T C = C, P = dbm, unless otherwise noted. Test circuit shown in Figure 1. (Notes, 3) PARAMETER CONDITIONS MIN TYP MAX UNITS Input Frequency Range to 8 MHz RF Input Frequency Range Low Side High Side to to 8 MHz MHz IF Output Frequency Range Requires External Matching to MHz RF Input Return Loss Z O = Ω, MHz to MHz > db Input Return Loss Z O = Ω, MHz to 8MHz > db IF Output Impedance Differential at MHz 33Ω 1.pF R C Input Power f = MHz to 8MHz 1 dbm to RF Leakage f = MHz to 8MHz, Requires C < 3 dbm to IF Leakage f = MHz to 8MHz < 1 dbm RF to Isolation f RF = MHz to MHz >38 db RF to IF Isolation f RF = MHz to MHz > db f
LTC AC Electrical Characteristics V CC = 3.3V, V CCIF = 3.3V, = Low, T C = C, P = dbm, P RF = 3dBm ( 3dBm/tone for -tone tests),unless otherwise noted. Test circuit shown in Figure 1. (Notes, 3) Low Side Downmixer Application: RF = MHz to MHz, IF = MHz, f = f RF f IF PARAMETER CONDITIONS MIN TYP MAX UNITS Conversion Gain RF = MHz RF = MHz RF = 8MHz Conversion Gain Flatness RF = MHz ±3MHz, = MHz, IF = ±3MHz ±.1 db Conversion Gain vs Temperature T C = C to C, RF = MHz. db/ C -Tone Input 3 rd Order Intercept ( f = MHz) -Tone Input nd Order Intercept ( f = 1MHz, f IM = f RF1 f RF ) RF = MHz RF = MHz RF = 8MHz f RF1 = 31MHz, f RF = MHz, f = MHz.... db.. dbm.8 3. dbm SSB Noise Figure SSB Noise Figure Under Blocking RF Output Spurious Product (f RF = f + f IF /) 3RF 3 Output Spurious Product (f RF = f + f IF /3) RF = MHz RF = MHz RF = 8MHz f RF = MHz, f = MHz, f BCK = MHz, P BCK = dbm.3.3 db.8. db f RF = MHz at dbm, f = MHz, f IF = MHz 8.3 dbc f RF = MHz at dbm, f = MHz, f IF = MHz dbc Input 1dB Compression RF = MHz, V CCIF = 3.3V RF = MHz, V CCIF = V.. dbm High Side Downmixer Application: RF = MHz to 8MHz, IF = MHz, f = f RF + f IF PARAMETER CONDITIONS MIN TYP MAX UNITS Conversion Gain RF = MHz RF = MHz RF = MHz Conversion Gain Flatness RF = MHz ±3MHz, = 3MHz, IF = ±3MHz ±.1 db Conversion Gain vs Temperature T C = C to C, RF = MHz. db/ C -Tone Input 3 rd Order Intercept ( f = MHz) -Tone Input nd Order Intercept ( f = 1MHz, f IM = f RF f RF1 ) SSB Noise Figure RF Output Spurious Product (f RF = f f IF/ ) 3 3RF Output Spurious Product (f RF = f f IF/3 ) RF = MHz RF = MHz RF = MHz f RF1 = MHz, f RF = MHz, f = MHz RF = MHz RF = MHz RF = MHz f RF = MHz at dbm, f = MHz f IF = MHz f RF = MHz at dbm, f = MHz f IF = MHz Input 1dB Compression RF = MHz, V CCIF = 3.3V RF = MHz, V CCIF = V 8...3 db..1 dbm. 3.8 dbm.. db. dbc dbc.3. dbm f 3
LTC DC Electrical Characteristics V CC = 3.3V, V CCIF = 3.3V, = Low, T C = C, unless otherwise noted. Test circuit shown in Figure 1. (Note ) PARAMETER CONDITIONS MIN TYP MAX UNITS Power Supply Requirements (V CC, V CCIF ) V CC Supply Voltage (Pins and ) 3.1 3.3 3. V V CCIF Supply Voltage (Pins and 1) 3.1 3.3.3 V V CC Supply Current (Pins + ) V CCIF Supply Current (Pins + 1) Total Supply Current (V CC + V CCIF ) Total Supply Current Shutdown = High µa Shutdown Logic Input () Low = On, High = Off Input High Voltage (Off) 3. V Input Low Voltage (On).3 V Input Current.3V to V CC +.3V 3 µa Turn On Time. µs Turn Off Time. µs Temperature Sensing Diode (TEMP) DC Voltage at T J = C I IN = µa I IN = 8µA Voltage Temperature Coefficient I IN = µa I IN = 8µA 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 : The LTC is guaranteed functional over the C to C case temperature range. 8.1 8. 1.3 1.3 38 Note 3: SSB Noise Figure measurements performed with a small-signal noise source, bandpass filter and db matching pad on RF input, db matching pad on the input, bandpass filter on the IF output and no other RF signals applied. ma mv mv mv/ C mv/ C Typical DC Performance Characteristics = Low, Test circuit shown in Figure 1. V CC Supply Current vs Supply Voltage (Mixer and Buffer) V CCIF Supply Current vs Supply Voltage (IF Amplifier) Total Supply Current vs Temperature (V CC + V CCIF ) SUPPLY CURRENT (ma) 8 T C = C T C = C T C = 8 C T C = C SUPPLY CURRENT (ma) 8 T C = C T C = 8 C T C = C T C = C SUPPLY CURRENT (ma) 1 V CC = 3.3V, V CCIF = V (DUAL SUPPLY) V CC = V CCIF = 3.3V (SINGLE SUPPLY) 3. 3.1 3. 3.3 3. 3. 3. V CC SUPPLY VOLTAGE (V) G1 3. 3.3 3. 3....8.1. V CCIF SUPPLY VOLTAGE (V) G 1 8 1 CASE TEMPERATURE ( C) G3 f
Typical AC Performance Characteristics LTC Low Side V CC = 3.3V, V CCIF = 3.3V, = Low, T C = C, P = dbm, P RF = 3dBm ( 3dBm/tone for two-tone tests, f = MHz), IF = MHz, unless otherwise noted. Test circuit shown in Figure 1. Conversion Gain and vs RF Frequency 1 Conversion Gain and vs RF Frequency 1 (dbm) 3 1 P = 1dBm P = dbm P = dbm GC (db) (dbm) 3 1 V CC = V CCIF V CC = 3.1V V CC = 3.3V V CC = 3.V (db) 1 1 1....8.....8. G 1....8.....8. G Conversion Gain and vs RF Frequency 1 Input P1dB vs RF Frequency (dbm) 3 1 T C = C T C = C T C = 8 C T C = C (db) INPUT P1dB (dbm) 1 V CCIF = V V CCIF = 3.3V 1 1....8.....8. G....8.....8. P = 1dBm P = dbm P = dbm G SSB NF, DSB NF (db) 8 SSB NF and DSB NF vs RF Frequency. DSB NF SSB NF...8.....8. T C = C T C = C T C = 8 C T C = C G8 (db), (dbm) 8 8 MHz Conversion Gain, and NF vs Power NF T C = C T C = C T C = 8 C 8 3 1 1 3 INPUT POWER (dbm) G SSB NF (db) f
LTC Typical AC Performance Characteristics Low Side (continued) V CC = 3.3V, V CCIF = 3.3V, = Low, T C = C, P = dbm, P RF = 3dBm ( 3dBm/tone for two-tone tests, Δf = MHz), IF = MHz, unless otherwise noted. Test circuit shown in Figure 1. (db), (dbm), P1dB (dbm) Conversion Gain, and RF Input P1dB vs Temperature 8 RF = MHz V CCIF = V V CCIF = 3.3V P1dB 8 1 3 CASE TEMPERATURE ( C) G OUTPUT POWER (dbm) Single-Tone IF Output Power, and 3 3 Spurs vs RF Input Power IF OUT (RF = MHz) = MHz 3 RF (RF = MHz) 3RF 3 (RF = MHz) 8 3 3 1 RF INPUT POWER (dbm) G RELATIVE SPUR LEVEL (dbc) 8 and 3 3 Spurs vs Power RF = MHz P RF = dbm RF (RF = MHz) 3RF 3 (RF = MHz) INPUT POWER (dbm) G SSB NF (db) 1 1 1 SSB Noise Figure vs RF Blocker Level to RF Leakage vs Frequency RF/ Isolation RF = MHz = MHz BCKER = MHz P = 1dBm P = dbm P = dbm 1 RF BCKER POWER (dbm) G TO RF LEAKAGE (dbm) 3. C = 1pF C =.pf C = OPEN C =.pf...8.....8 FREQUENCY (GHz) G ISOLATION (db) 3 TO IF RF TO RF TO IF.....8.....8. RF/ FREQUENCY (GHz) G1 DISTRIBUTION (%) 3 3 1 MHz Conversion Gain Histogram MHz Histogram MHz SSB NF Histogram.8 T C = 8 C T C = C T C = C RF = MHz...1..3.....8. CONVERSION GAIN (db) G DISTRIBUTION (%) 1 3. T C = 8 C T C = C T C = C RF = MHz.1...3..1.. (dbm) G1 DISTRIBUTION (%) 3 3 1. T C = 8 C T C = C T C = C RF = MHz.3..1...3. SSB NOISE FIGURE (db) G f
LTC Typical AC Performance Characteristics High Side V CC = 3.3V, V CCIF = 3.3V, = Low, T C = C, P = dbm, P RF = 3dBm ( 3dBm/tone for two-tone tests, Δf = MHz), IF = MHz, unless otherwise noted. Test circuit shown in Figure 1. Conversion Gain and vs RF Frequency 1 Conversion Gain and vs RF Frequency 1 (dbm) (db) (dbm) GC (db). P = 1dBm P = dbm P = dbm....8.....8 G1 V CC = V CCIF V CC = 3.1V V CC = 3.3V V CC = 3.V.....8.....8 G (dbm). Conversion Gain and vs RF Frequency T C = C T C = C T C = 8 C T C = C....8.....8 G1 1 (db) INPUT P1dB (dbm) 1 Input P1dB vs RF Frequency P = 1dBm P = dbm P = dbm V CCIF = V V CCIF = 3.3V.....8.....8 G SSB NF, DSB NF (db) 8 SSB NF and DSB NF vs RF Frequency.. DSB NF SSB NF T C = C T C = C T C = 8 C T C = C...8.....8. G3 GC (db), (dbm) MHz Conversion Gain, and NF vs Power 3 1 1 NF 1 1 T C = C 8 T C = C T C = 8 C 3 1 1 3 INPUT POWER (dbm) G SSB NF (db) f
LTC Pin Functions (Pins 1, 8,,, Exposed Pad Pin 1): Ground. These pins must be soldered to the RF ground plane on the circuit board. The exposed pad metal of the package provides both electrical contact to ground and good thermal contact to the printed circuit board. 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. A series DC-blocking capacitor should be used to avoid damage to the integrated transformer when DC voltage is present at the RF input. The RF input is impedance matched, as long as the input is driven with a dbm ±db source between.ghz and.8ghz. CT (Pin 3): RF Transformer Secondary Center-Tap. This pin may require a bypass capacitor to ground. See the Applications Information section. This pin has an internally generated bias voltage of 1.V. It must be DC-isolated from ground and V CC. (Pin ): Shutdown Pin. When the input voltage is less than.3v, the IC is enabled. When the input voltage is greater than 3V, the IC is disabled. Typical pin input current is less than μa. This pin must not be allowed to float. V CC1 (Pin ) and V CC (Pin ): Power Supply Pins for the Buffer and Bias Circuits. These pins are internally con- nected and must be externally connected to a regulated 3.3V supply, with bypass capacitors located close to the pins. Typical current consumption is ma. BIAS (Pin ): This Pin Allows Adjustment of the Buffer Current. Typical DC voltage is.v. (Pin ): Single-Ended Input for the Local Oscillator. This pin is internally connected to the primary side of the RF input transformer, which has low DC resistance to ground. A series DC blocking capacitor must be used to avoid damage to the integrated transformer if DC voltage is present at the input. TEMP (Pin ): Temperature Sensing Diode. This pin is connected to the anode of a diode that may be used to measure the die temperature, by forcing a current and measuring the voltage. IF (Pin ): DC Ground Return for the IF Amplifier. This pin must be connected to ground to complete the IF amplifier s DC current path. Typical DC current is 8mA. IF (Pin ) and IF + (Pin 1): Open-Collector Differential Outputs for the IF Amplifier. These pins must be connected to a DC supply through impedance matching inductors, or a transformer center-tap. Typical DC current consumption is ma into each pin. IFBIAS (Pin ): This Pin Allows Adjustment of the IF Amplifier Current. Typical DC voltage is.1v. Block Diagram RF 1 1 IFBIAS IF + IF IF IF EXPOSED PAD AMP AMP TEMP 3 CT BIAS PASSIVE MIXER V CC1 PINS ARE NOT SHOWN V CC BIAS BD 8 f
Test Circuit LTC IF OUT MHz Ω T1 :1 C L1 L V CCIF 3.1V TO.3V C8 C 1 1 IFBIAS IF + IF LTC IF TEMP RF IN Ω C1 RF L 1 C3 C 3 CT IN Ω (V/3.3V) V CC1 BIAS V CC 8 V CC 3.1V TO 3.V C C F1..1.1 RF BIAS DC8A BOARD STACK-UP (NELCO N-) IF (MHz) L1, L vs IF Frequencies L1, L (nh) 1 1 1 3 8 38 3 REF DES VALUE SIZE COMMENTS C1.pF AVX ACCU-P C Open C3 1.pF AVX ACCU-P C, C pf AVX C pf AVX C, C8 1µF 3 AVX L1, L 1nH 3 Coilcraft 3CS L.nH Coilcraft HP T1 TC-1W-ALN+ Mini-Circuits Note: For IF = MHz to MHz, use TC-1W-1LN+ for T1 Figure 1. Standard Downmixer Test Circuit Schematic (MHz IF) f
LTC Applications Information Introduction The LTC consists of a high linearity passive doublebalanced mixer core, IF buffer amplifier, buffer amplifier and bias/shutdown circuits. See the Block Diagram section for a description of each pin function. The RF and inputs are single-ended. The IF output is differential. Low side or high side injection can be used. The evaluation circuit, shown in Figure 1, utilizes bandpass IF output matching and an IF transformer to realize a Ω single-ended IF output. The evaluation board layout is shown in Figure. For the RF input to be matched, the input must be driven. A broadband input match is realized with C1 =.pf and L =.nh. The measured RF input return loss is shown in Figure for frequencies of.ghz, GHz and.ghz. These frequencies correspond to the lower, middle and upper values of the range. As shown in Figure, the RF input impedance is somewhat dependent on frequency. The RF input impedance and input reflection coefficient, versus RF frequency, is listed in Table 1. The reference plane for this data is Pin of the IC, with no external matching, and the is driven at GHz. LTC TO MIXER RF IN C1 RF L 3 CT C F Figure. Evaluation Board Layout RF Input The mixer s RF input, shown in Figure 3, is connected to the primary winding of an integrated transformer. A Ω match is realized with a series capacitor (C1) and a shunt inductor (L). The primary side of the RF transformer is DC-grounded internally and the DC resistance of the primary is approximately.ω. A DC blocking capacitor is needed if the RF source has DC voltage present. The secondary winding of the RF transformer is internally connected to the passive mixer. The center-tap of the transformer secondary is connected to Pin 3 (CT) to allow the connection of bypass capacitor, C. The value of C is frequency-dependent and can be tuned for better leakage performance. When used, C should be located within mm of Pin 3 for proper high frequency decoupling. The nominal DC voltage on the CT pin is 1.V. RF PORT RETURN SS (db) 1 3 3.. Figure 3. RF Input Schematic =.GHz =.GHz = GHz...8.....8. Figure. RF Input Return Loss F F3 f
Applications Information Table 1. RF Input Impedance and S (at Pin, No External Matching, Input Driven at GHz) FREQUENCY INPUT S (GHz) IMPEDANCE MAG ANGLE. 8.8 + j.1. 3.8. 8. + j..1 31... + j1.3... + j33..38 3..8 1. + j1.1.31 1... + j..1.1.. + j.1. 3...8 + j.1... 3.1 + j..8 3..8. + j3.. 3...3 + j.. 3. Input The mixer s input circuit, shown in Figure, consists of a balun transformer and a two-stage high speed limiting differential amplifier to drive the mixer core. The LTC s amplifiers are optimized for the.ghz to.8ghz frequency range. frequencies above or below this frequency range may be used with degraded performance. The mixer s input is directly connected to the primary winding of an integrated transformer. A Ω match is realized with a series 1.pF capacitor (C3). Measured input return loss is shown in Figure. The amplifiers are powered through V CC1 and V CC (Pin and Pin ). When the chip is enabled ( = LTC low), the internal bias circuit provides a regulated ma current to the amplifier s bias input, which in turn causes the amplifiers to draw approximately ma of DC current. This ma reference current is also connected to BIAS (Pin ) to allow modification of the amplifier s DC bias current for special applications. The recommended application circuits require no amplifier bias modification, so this pin should be left open-circuited. The nominal input level is +dbm although the limiting amplifiers will deliver excellent performance over a ±3dB input power range. input power greater than +dbm may be used with slightly degraded performance. The input impedance and input reflection coefficient, versus frequency, is shown in Table. Table. Input Impedance vs Frequency (at Pin, No External Matching) FREQUENCY INPUT S (GHz) IMPEDANCE MAG ANGLE.. + j..... + j..1.. 8. + j..3 8.1. 33. + j.3.3..8 3. + j..3.. + j.3. 8.1.. + j.. 3.3. + j..... + j3.8. 88.8.8. j1.3... j... LTC TO MIXER BIAS BUFFER ma C3 IN PORT RETURN SS (db) 1 BIAS V CC1 V CC F 3.....8.....8. FREQUENCY (GHz) F Figure. Input Schematic Figure. Input Return Loss f
LTC Applications Information IF Output The IF amplifier, shown in Figure, has differential open-collector outputs (IF + and IF ), a DC ground return pin (IF), and a pin for modifying the internal bias (IFBIAS). The IF outputs must be biased at the supply voltage (V CCIF ), which is applied through matching inductors L1 and L. Alternatively, the IF outputs can be biased through the center tap of a transformer. The common node of L1 and L can be connected to the center tap of the transformer. Each IF output pin draws approximately ma of DC supply current (8mA total). IF (Pin ) must be grounded or the amplifier will not draw DC current. For the highest conversion gain, high-q wire-wound chip inductors are recommended for L1 and L, especially when using V CCIF = 3.3V. Low cost multilayer chip inductors may be substituted, with a slight degradation in performance. Grounding through inductor L3 may improve -IF and RF-IF leakage performance in some applications, but is otherwise not necessary. High DC resistance in L3 will reduce the IF amplifier supply current, which will degrade RF performance. R1 (OPTION TO REDUCE DC POWER) LTC V CC IF OUT L1 V CCIF Figure. IF Amplifier Schematic with Transformer-Based Bandpass Match T1 :1 C L C8 1 IFBIAS IF + IF BIAS ma IF AMP 8mA L3 (OR SHORT) IF F For optimum single-ended performance, the differential IF outputs must be combined through an external IF transformer or discrete IF balun circuit. The evaluation board (see Figures 1 and ) uses a :1 ratio IF transformer for impedance transformation and differential to single-ended transformation. It is also possible to eliminate the IF transformer and drive differential filters or amplifiers directly. The IF output impedance can be modeled as 33Ω in parallel with 1.pF at IF frequencies. An equivalent smallsignal model is shown in Figure 8. Frequency-dependent differential IF output impedance is listed in Table 3. This data is referenced to the package pins (with no external components) and includes the effects of IC and package parasitics. LTC 1 IF + IF RIF Figure 8. IF Output Small-Signal Model Table 3. IF Output Impedance vs Frequency DIFFERENTIAL OUTPUT FREQUENCY (MHz) IMPEDANCE (R IF X IF (C IF )) 31 j (.pf) 31 j (.3pF) 1 33 j1 (1.pF) 33 j3 (1.pF) 3 3 j3 (1.pF) 38 3 j (1.pF) 3 j (1.pF) CIF Transformer-Based Bandpass IF Matching The IF output can be matched for IF frequencies as low as MHz, or as high as MHz, using the bandpass IF matching shown in Figures 1 and. L1 and L resonate with the internal IF output capacitance at the desired IF frequency. The value of L1, L is calculated as follows: L1, L = 1/[( π f IF ) C IF ] F8 where C IF is the internal IF capacitance (listed in Table 3). Values of L1 and L are tabulated in Figure 1 for various IF frequencies f
Applications Information 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 C are calculated to realize a phase shift at the desired IF frequency and provide a Ω single-ended output, using the following equations. Inductor L is used to cancel the internal capacitance C IF and supplies bias voltage to the IF pin. C1 is a DC blocking capacitor. L,L = R IF R OUT ω IF 1 C, C = ω IF R IF R OUT L = X IF ω IF 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 previous calculation. The typical performances of the LTC using a discrete IF balun matching and a transformer-based IF matching are shown in Figure. With an IF frequency of MHz, the actual components values for the discrete balun are: L, L = 3nH, L = 8nH and C, C = 3.3pF Measured IF output return losses for transformer-based bandpass IF matching and discrete balun IF matching (MHz IF frequency) are plotted in Figure. A discrete balun has less insertion loss than a balun transformer, but the IF bandwidth of a discrete balun is less than that of a transformer. IF Amplifier Bias The IF amplifier delivers excellent performance with V CCIF = 3.3V, which allows the V CC and V CCIF supplies to be common. With V CCIF increased to V, the RF input P1dB increases by more than 3dB, at the expense of higher power consumption. Mixer performance at MHz is shown in Table with V CCIF = 3.3V and V. R1 (OPTION TO REDUCE DC POWER) LTC V CC 1 IFBIAS IF + IF BIAS ma C L V CCIF L IF AMP C1 L LTC Table. Performance Comparison with V CCIF = 3.3V and V (RF = MHz, Low Side, IF = MHz) V CCIF (V) I CCIF (ma) C 8mA IF OUT L3 (OR SHORT) IF F Figure. IF Amplifier Schematic with Discrete IF Balun (dbm) 8 IF = MHz W SIDE TC-1W-1LN+ BALUN DISCRETE BALUN 3....1.3....1.3 F Figure. Conversion Gain and vs RF Frequency IF PORT RETURN SS (db) 1 3 (db) P1dB (dbm) L1, L = 1 nh L1, L = 8nH L1, L = 3nH DISCRETE BALUN MHz (dbm) 1 3 3 IF FREQUENCY (MHz) F GC (db) NF (db) 3.3 8....3. 1.... Figure. IF Output Return Loss f
LTC Applications Information The IFBIAS pin (Pin ) is available for reducing the DC current consumption of the IF amplifier, at the expense of reduced performance. This pin should be left open-circuited for optimum performance. The internal bias circuit produces a ma reference for the IF amplifier, which causes the amplifier to draw approximately 8mA. If resistor R1 is connected to Pin as shown in Figure, a portion of the reference current can be shunted to ground, resulting in reduced IF amplifier current. For example, R1 = 1kΩ will shunt away 1.mA from Pin and the IF amplifier current will be reduced by % to approximately ma. The nominal, open-circuit DC voltage at Pin is.1v. Table lists RF performance at MHz versus IF amplifier current. Table. Mixer Performance with Reduced IF Amplifier Current (RF = MHz, Low Side, IF = MHz, V CC = V CCIF = 3.3V) R1 (kω) I CCIF (ma) (db) (dbm) P1dB (dbm) NF (db) OPEN 8....3. 8......... 1..3 3.8.3. (RF = MHz, High Side, IF = MHz, V CC = V CCIF = 3.3V) R1 (kω) I CCIF (ma) (db) (dbm) P1dB (dbm) NF (db) OPEN 8.3.... 8. 3.8.... 3... 1..8..3. Shutdown Interface Figure shows a simplified schematic of the pin interface. To disable the chip, the voltage must be higher than 3.V. If the shutdown function is not required, the pin should be connected directly to. The voltage at the pin should never exceed the power supply voltage (V CC ) by more than.3v. If this should occur, the supply current could be sourced through the ESD diode, potentially damaging the IC. The pin must be pulled high or low. If left floating, then the on/off state of the IC will be indeterminate. If a three-state condition can exist at the pin, then a pull-up or pull-down resistor must be used. V CC1 LTC Ω Figure. Shutdown Input Circuit F Temperature Diode The LTC provides an on-chip diode at Pin (TEMP) for chip temperature measurement. Pin is connected to the anode of an internal ESD diode with its cathode connected to internal ground. The chip temperature can be measured by injecting a constant DC current into Pin and measuring its DC voltage. The voltage vs temperature coefficient of the diode is about 1.3mV/ C with µa current injected into the TEMP pin. Figure shows a typical temperature-voltage behavior when µa and 8µA currents are injected into Pin. TEMP DIODE VOLTAGE (mv) 8 8 8µA µa 8 JUNCTION TEMPERATURE ( C) F Figure. TEMP Diode Voltage vs Junction Temperature (T J ) Supply Voltage Ramping Fast ramping of the supply voltage can cause a current glitch in the internal ESD protection circuits. Depending on the supply inductance, this could result in a supply voltage transient that exceeds the maximum rating. A supply voltage ramp time of greater than 1ms is recommended. f
LTC Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. UF Package -Lead Plastic QFN (mm mm) (Reference LTC DWG # -8-). ±..3 ±..1 ±.. ±. ( SIDES) PACKAGE OUTLINE.3 ±.. BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS BOTTOM VIEW EXPOSED PAD. ±.. ±. R =. ( SIDES) TYP 1 PIN 1 TOP MARK (NOTE ).1 ±. (-SIDES) PIN 1 NOTCH R =. TYP OR.3 CHAMFER. ±. 1. REF.. NOTE: 1. DRAWINONFORMS TO JEDEC PACKAGE OUTLINE MO- VARIATION (WGGC). DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED.1mm ON ANY SIDE. EXPOSED PAD SHALL BE SOLDER PLATED. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 CATION ON THE TOP AND BOTTOM OF PACKAGE (UF) QFN -.3 ±.. BSC 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. f 1
LTC Typical Application IF OUT Ω V CCIF 3.3V RF IN Ω 1µF.pF 3.3pF pf.nh MHz IF Output Matching RF TM-1 (SYNERGY) pf nh IF BIAS pf nh pf IF + IF IF TEMP 1.pF IN Ω (dbm), SSB NF (db) 3 8 Conversion Gain, and NF vs RF Frequency SSB NF IF = MHz W SIDE..1.3....1.3 TAb 8 3 1 (db) V CC1 V CC V CC 3.3V 1µF pf TAa Related Parts PART NUMBER DESCRIPTION COMMENTS Infrastructure LTCX MHz to GHz 3.3V Downconverting Mixers 8dB Gain, dbm, db NF, 3.3V/mA Supply LT MHz to 3.GHz, V Downconverting Mixer.3dB Gain, 3.dBm and.db NF at 1MHz, V/8mA Supply LT MHz to 3.8GHz, 3.3V Downconverting Mixer.dB Gain,.dBm and.db NF at 1MHz, 3.3V/8mA Supply LTCx MHz to.ghz Dual Downconverting Mixer Family 8.dB Gain,.dBm,.dB NF, 3.3V/38mA Supply LTC 3MHz to GHz 3.3V Dual Downconverting Mixer db Gain,.8dBm and.db NF at 1MHz, 3.3V/mA Supply LTC-X 3MHz Low Distortion IF Amp/ADC Driver Fixed Gain of 8dB, db, db and db; >3dBm OIP3 at 3MHz, Differential I/O LTC GHz -Bit ADC Buffer dbm OIP3 to 3MHz, Programmable Fast Recovery Output Clamping LTC 31dB Linear Analog VGA 3dBm OIP3 at MHz, Continuous Variable Gain Range db to 1dB LT Ultralow Distort IF Digital VGA 8dBm OIP3 at MHz, db to db Gain Range,.dB Gain Steps LT8 MHz to.ghz Upconverting Mixer dbm OIP3 at MHz,.dBm at 1.GHz, Integrated RF Transformer LT 1.GHz to 3.8GHz Upconverting Mixer.3dBm OIP3 at.ghz, NF =.db, 3.3V Supply, Single-Ended and RF Ports LTC88-1 MHz to GHz I/Q Modulator 31dBm OIP3 at.ghz,.dbm/hz Noise Floor RF Power Detectors LTC8 GHz RMS Detector with -Bit ADC db Dynamic Range, ±1dB Accuracy Over Temperature, 3mA Current, ksps LT81 GHz Low Power RMS Detector db Dynamic Range, ±1dB Accuracy Over Temperature, 1.mA Supply Current LTC8 MHz to GHz RMS Detector db Dynamic Range, ±.db Accuracy Over Temperature, ±.db Linearity Error LTC83 Dual GHz RMS Power Detector Up to db Dynamic Range, ±.db Accuracy Over Temperature, >db Isolation ADCs LTC8 -Bit, Msps ADC 8dBFS Noise Floor, >83dB SFDR at MHz LTC8 Dual -Bit, Msps Low Power ADC.dB SNR, 88dB SFDR, mw Power Consumption LTC8- Dual -Bit, Msps Serial Output ADC 3.1dB SNR, 88dB SFDR, mw Power Consumption LT 3 PRINTED IN USA Linear Technology Corporation 3 McCarthy Blvd., Milpitas, CA 3-1 (8) 3-1 FAX: (8) 3- www.linear.com LINEAR TECHNOGY CORPORATION f