LTC1064ACJ

LTC1064 Low Noise, Fast, Quad Universal Filter Building Block FEATURES s s DESCRIPTION The LTC®1064 consists of four high speed, low noise switched-capacitor filter building blocks. Each filter building block, together with an external clock and three to five resistors can provide various 2nd order functions like lowpass, highpass, bandpass and notch. The center frequency of each 2nd order function can be tuned with an external clock, or a clock and resistor ratio. For Q ≤ 5, the center frequency range is from 0.1Hz to 100kHz. For Q ≤ 3, the center frequency range can be extended to 140kHz. Up to 8th order filters can be realized by cascading all four 2nd order sections. Any classical filter realization (such as Butterworth, Cauer, Bessel and Chebyshev) can be formed. A customized monolithic version of the LTC1064 including internal thin film resistors can be obtained for high volume applications. Consult LTC Marketing for details. The LTC1064 is manufactured using Linear Technology’s enhanced LTCMOSTM silicon gate process. , LTC and LT are registered trademarks of Linear Technology Corporation. LTCMOS is a trademark of Linear Technology Corporation. s s s s s s s Four Filters in a 0.3-Inch Wide Package One Half the Noise of the LTC1059/LTC1060/ LTC1061 Devices Maximum Center Frequency: 140kHz Maximum Clock Frequency: 7MHz Clock-to-Center Frequency Ratio of 50:1 and 100:1 Simultaneously Available Power Supplies: ±2.375V to ± 8V Low Offsets Low Harmonic Distortion Customized Version with Internal Resistors Available APPLICATIONS s s s s Anti-Aliasing Filters Wide Frequency Range Tracking Filters Spectral Analysis Loop Filters TYPICAL APPLICATION Clock-Tunable 8th Order Cauer Lowpass Filter with fCUTOFF up to 100kHz 13k 66.5k 22.1k VIN 10k 18.25k 10.7k 1 2 3 4 5 6 8V 7 0.1µF 10k 49.9K 11.5K (FROM RH2, RL2) 8 9 10 11 12 24 23 22 21 20 10k 12.1k 17.4k RL2 26.7k RH2 102k PIN 12 INV B HPB/NB BPB LPB SB AGND V+ SA LPA BPA HPA/NA INV A LTC1064 INV C HPC/NC BPC LPC SC V– CLK 0 –15 –30 GAIN (dB) –45 –60 –75 –90 –105 –120 –135 1k 19 18 17 16 15 14 13 41.2k 12.7k 14k 121k 10k 5MHz 8V 0.1µF –8V 50/100 LPD BPD HPD INV D VOUT FOR fCLK = 5MHz, ADD C1 = 10pF BETWEEN PINS 4, 1 C2 = 10pF BETWEEN PINS 21, 24 C3 = 27pF BETWEEN PINS 9, 12 WIDEBAND NOISE ≅ 140µVRMS 1064 TA01 U U U Gain vs Frequency fCLK = 5MHz RIPPLE = ±0.1dB fCLK = 1MHz RIPPLE = ±0.05dB 10k 100k INPUT FREQUENCY (Hz) 1M 1064 TA02 1 LTC1064 ABSOLUTE MAXIMUM RATINGS Total Supply Voltage (V + to V –) ............................. 16V Power Dissipation............................................. 500mW Operating Temperature Range LTC1064AC/LTC1064C.................... – 40°C to 85°C LTC1064AM/LTC1064M ................ – 55°C to 125°C Storage Temperature Range ................ – 65°C to 150°C Lead Temperature (Soldering, 10 sec)................. 300°C PACKAGE/ORDER INFORMATION TOP VIEW INV B HPB/NB BPB LPB SB AGND V+ SA LPA 1 2 3 4 5 6 7 8 9 24 INV C 23 HPC/NC 22 BPC 21 LPC 20 SC 19 V – 18 CLK 17 50/100 16 LPD 15 BPD 14 HPD 13 INV D N PACKAGE 24-LEAD PLASTIC DIP ORDER PART NUMBER LTC1064ACJ LTC1064CJ LTC1064AMJ LTC1064MJ LTC1064ACN LTC1064CN BPA 10 HPA/NA 11 INV A 12 J PACKAGE 24-LEAD CERAMIC DIP TJMAX = 150°C, θJA = 100°C/ W (J) TJMAX = 110°C, θJA = 65°C/ W (N) Consult factory for Industrial grade parts. ELECTRICAL CHARACTERISTICS (Internal Op Amps) TA = 25°C, unless otherwise specified. PARAMETER Operating Supply Voltage Range Voltage Swings Output Short-Circuit Current (Source/Sink) DC Open-Loop Gain GBW Product Slew Rate CONDITIONS VS = ± 5V, RL = 5k q VS = ± 5V VS = ± 5V, RL = 5k VS = ± 5V VS = ± 5V 2 U U W WW U W TOP VIEW INV B HPB/NB BPB LPB SB AGND V+ SA LPA 1 2 3 4 5 6 7 8 9 24 INV C 23 HPC/NC 22 BPC 21 LPC 20 SC 19 V – 18 CLK 17 50/100 16 LPD 15 BPD 14 HPD 13 INV D ORDER PART NUMBER LTC1064CS BPA 10 HPA/NA 11 INV A 12 SW PACKAGE 24-LEAD PLASTIC SO TJMAX = 100° C, θJA = 85°C/ W MIN ± 2.375 ± 3.2 ± 3.1 TYP ± 3.6 3 80 7 10 MAX ±8 UNITS V V V mA dB MHz V/µs LTC1064 ELECTRICAL CHARACTERISTICS (Complete Filter) VS = ± 5V, TA = 25°C, TTL clock input level, unless otherwise specified. PARAMETER Center Frequency Range, fO Input Frequency Range Clock-to-Center Frequency Ratio, fCLK /fO CONDITIONS VS = ± 8V, Q ≤ 3 LTC1064 LTC1064A (Note 1) fCLK = 1MHz, fO = 20kHz, Pin 17 High Sides A, B, C: Mode 1, R1 = R3 = 5k, R2 = 5k, Q = 10, Sides D: Mode 3, R1 = R3 = 50k R2 = R4 = 5k Same as Above, Pin 17 Low, fCLK = 1MHz fO = 10kHz Sides A, B, C Side D fCLK = 1MHz fCLK = 4MHz, fO = 80kHz, Pin 17 High Sides A, B, C: Mode 1, VS = ±7.5V R1 = R3 = 50k, R2 = 5k, Q = 5 Side D: Mode 3, R1 = R3 = 50k R2 = R4 = 5k, fCLK = 4MHz Same as Above, Pin 17 Low fCLK = 4MHz, fO = 40kHz Sides A, B, C: Mode 1, Q = 10 Side D: Mode 3, fCLK = 1MHz Mode 1, 50:1, fCLK < 2MHz Mode 1, 100:1, fCLK < 2MHz Mode 3, fCLK < 2MHz fCLK = 1MHz, 50:1 or 100:1 fCLK = 1MHz, 50:1 or 100:1 fCLK = 1MHz, 50:1 or 100:1 fCLK < 1MHz Mode 1, Q < 5, VS ≥ ± 5V MIN TYP 0.1 to 140 0 to 1 50 ± 0.3 MAX UNITS kHz MHz % % % % 100 ± 0.8 100 ± 0.9 0.4 q q q 50 ± 0.8 50 ± 0.9 LTC1064 LTC1064A (Note 1) 100 ± 0.3 q q % % % % % Clock-to-Center Frequency Ratio, Side-to-Side Matching Clock-to-Center Frequency Ratio, fCLK/fO (Note 2) LTC1064 LTC1064A (Note 1) LTC1064 LTC1064A (Note 1) 1 50 ± 0.6 50 ± 1.3 LTC1064 LTC1064 A (Note 1) Q Accuracy fO Temperature Coefficient Q Temperature Coefficient DC Offset Voltage VOS1 (Table 1) VOS2 (Table 1) VOS3 (Table 1) 100 ± 0.6 q q q q q Clock Feedthrough Maximum Clock Frequency Power Supply Current 9 q ±2 ±3 ±1 ±5 ±5 2 3 3 0.2 7 12 100 ± 1.3 6 8 15 45 45 23 26 % % % % ppm/°C ppm/°C ppm/°C mV mV mV mVRMS MHz mA mA The q denotes specifications which apply over the full operating temperature range. Note 1: Contact LTC Marketing. Note 2: Not tested, guaranteed by Design. Table 1. Output DC Offsets, One 2nd Order Section MODE 1 1b 2 3 VOSN PINS 2, 11, 14, 23 VOS1 [(1/Q) + 1 +  HOLP ] – VOS3 /Q   VOS1 [(1/Q) + 1 + (R2/R1)] – VOS3 /Q VOS1 [(1 + (R2/R1) + (R2/R3) + (R2/R4) – VOS3 (R2/R3)] × [ R4/(R2 + R4)] + VOS2[R2/(R2 + R4)] VOS2 VOSBP PINS 3, 10, 15, 22 VOS3 VOS3 VOS3 VOS3 VOSLP PINS 4, 9, 16, 21 VOSN – VOS2 ~(VOSN – VOS2)[1 + (R5/R6)] VOSN – VOS2 VOS1[1 + (R4/R1) + (R4/R2) + (R4/R3)] – VOS2(R4/R2) – VOS3(R4/R3) 3 LTC1064 BLOCK DIAGRA INV A (12) AGND (6) INV B (1) INV C (24) INV D (13) TYPICAL PERFORMANCE CHARACTERISTICS Mode 1, (fCLK /fO) = 50:1 20 Q ERROR (%) TA = 25°C Q=5 Q = 10 Q ERROR (%) 10 5 0 –5 VS = ± 2.5V 10 5 0 –5 VS = ± 2.5V Q ERROR (%) 15 VS = ± 5V VS = ± 7.5V CENTER FREQUENCY ERROR (%) CENTER FREQUENCY ERROR (%) 1.5 1.0 0.5 0 VS = ± 2.5V VS = ±5V 1.5 0.5 0 VS = ±5V CENTER FREQUENCY ERROR (%) TA = 25°C Q = 5 OR 10 0 10 20 30 40 50 60 70 80 90 100110 120 CENTER FREQUENCY (kHz) 1064 G01 4 UW W HPA/NA (11) BPA (10) LPA (9) V + (7) – + HPB/NB (2) + Σ – +∫ BPB (3) +∫ LPB (4) 50/100 (17) CLK (18) V – (19) – + HPC/NC (23) SA (8) + Σ – SB (5) +∫ BPC (22) +∫ LPC (21) BY TYING PIN 17 TO V +, ALL SECTIONS OPERATE WITH (fCLK/fO) = 50:1. BY TYING PIN 17 TO V –, ALL SECTIONS OPERATE WITH (fCLK/fO) = 100:1. LPD (16) BY TYING PIN 17 TO AGND, SECTIONS B, C OPERATE WITH (fCLK/fO) = 50:1 AND SECTIONS A, D OPERATE AT 100:1. – + HPD (14) + Σ – SC (20) +∫ BPD (15) +∫ – + +∫ +∫ 1064 BD Mode 1, (fCLK /fO) = 100:1 20 15 VS = ± 5V VS = ± 7.5V TA = 25°C Q=5 Q = 10 Mode 2, (fCLK /fO) = 25:1 20 15 10 5 0 –5 1.5 1.0 0.5 0 0 10 20 30 40 50 60 70 80 90 100110 120 CENTER FREQUENCY (kHz) 1064 G03 TA = 25°C Q = 10 PIN 17 AT V + (R2/R4) = 3 VS = ± 2.5V CC = 15pF VS = ±5V CC = 15pF VS = ± 7.5V TA = 25°C Q = 5 OR 10 1.0 VS = ± 2.5V VS = ± 7.5V VS = ± 2.5V VS = ±5V 0 10 20 30 40 50 60 70 80 90 100110 120 CENTER FREQUENCY (kHz) 1064 G02 LTC1064 TYPICAL PERFORMANCE CHARACTERISTICS Mode 2, (fCLK /fO) = 25:1 20 Q ERROR (%) Q ERROR (%) Q ERROR (%) 15 10 5 0 –5 TA = 25°C VS = ± 7.5V PIN 17 AT V + (R2/R4) = 3 Q=5 CC = 22pF Q=2 CC = 39pF CENTER FREQUENCY ERROR (%) 1.5 1.0 0.5 0 0 20 40 60 80 100 120140160180 200 CENTER FREQUENCY (kHz) 1064 G04 CENTER FREQUENCY ERROR (%) CENTER FREQUENCY ERROR (%) Q=5 Q=2 Mode 3, (fCLK /fO) = 50:1 20 Q ERROR (%) 15 10 5 0 –5 CENTER FREQUENCY ERROR (%) 1.5 1.0 0.5 0 0 10 20 30 40 50 60 70 80 90 100 110 120 CENTER FREQUENCY (kHz) 1064 G07 Q ERROR (%) 15 10 5 0 –5 VS = ± 5V VS = ± 7.5V VS = ± 5V VS = ± 7.5V WIDEBAND NOISE (µV/RMS) TA = 25°C CC = 15pF R2 = R4 VS = ± 7.5V Q=2 Q=1 VS = ± 7.5V VS = ± 2.5V VS = ±5V CENTER FREQUENCY ERROR (%) Power Supply Current vs Supply Voltage 48 44 POWER SUPPLY CURRENT (mA) 40 36 32 28 24 20 16 12 8 4 0 0 2 4 6 8 10 12 14 16 18 20 22 24 POWER SUPPLY VOLTAGE (V + – V –) 1064 G10 UW Mode 2, (fCLK /fO) = 50:1 20 15 10 5 0 –5 1.5 1.0 0.5 0 0 10 20 30 40 50 60 70 80 90 100110 120 CENTER FREQUENCY (kHz) 1064 G05 Mode 3, (fCLK /fO) = 50:1 20 15 10 5 0 –5 TA = 25°C CC = 5pF R2 = R4 Q=5 Q = 10 VS = ± 7.5V VS = ± 2.5V VS = ± 5V VS = ± 7.5V TA = 25°C PIN 17 AT V – (R2/R4) = 3 Q=5 Q = 10 VS = ± 5V VS = ± 2.5V VS = ±5V VS = ± 2.5V VS = ± 7.5V 1.5 1.0 0.5 0 VS = ± 2.5V VS = ±5V VS = ± 7.5V 0 10 20 30 40 50 60 70 80 90 100110 120 CENTER FREQUENCY (kHz) 1064 G06 Mode 3, (fCLK /fO) = 100:1 240 20 TA = 25°C CC = 5pF R2 = R4 Q = 10 Wideband Noise vs Q 220 200 180 160 140 120 100 80 60 40 20 0 ANY OUTPUT R3 = R1 ONE SECOND ORDER SECTION MODE 1 OR 3 100:1 OR 50:1 VS = ± 2.5V ± 7.5V ± 5V ±2.5V VS = ± 2.5V 1.5 1.0 0.5 0 0 10 20 30 40 50 60 70 80 90 100110 120 CENTER FREQUENCY (kHz) 1064 G08 0 2 4 6 8 10 12 14 16 18 20 22 24 Q 1064 G09 Harmonic Distortion, 8th Order LP Butterworth, fC = 20kHz, THD = 0.015% for 3VRMS Input –55°C 25°C 125°C 1064 G11 5 LTC1064 PIN FUNCTIONS V +, V – (Pins 7, 19): Power Supplies. They should be bypassed with a 0.1µF ceramic capacitor. Low noise, nonswitching power supplies are recommended. The device operates with a single 5V supply and with dual supplies. The absolute maximum operating power supply voltage is ± 8V. CLK (Pin 18): Clock. For ± 5V supplies the logic threshold level is 1.4V. For ± 8V and 0V to 5V supplies the logic threshold levels are 2.2V and 3V respectively. The logic threshold levels vary ± 100mV over the full military temperature range. The recommended duty cycle of the input clock is 50%, although for clock frequencies below 500kHz, the clock “on” time can be as low as 200ns. The maximum clock frequency for ± 5V supplies is 4MHz. For ± 7V supplies and above, the maximum clock frequency is 7MHz. AGND (Pin 6): Analog Ground. When the LTC1064 operates with dual supplies, Pin 6 should be tied to system ground. When the LTC1064 operates with a single positive supply, the analog ground pin should be tied to 1/2 supply and it should be bypassed with a 1µF solid tantalum in parallel with a 0.1µF ceramic capacitor, Figure 1. The positive input of all the internal op amps, as well as the common reference of all the internal switches, are internally tied to the analog ground pin. Because of this, a very “clean” ground is recommended. 50/100 (Pin 17): By tying Pin 17 to V +, all filter sections operate with a clock-to-center frequency ratio internally set at 50:1. When Pin 17 is at mid-supplies, sections B and C operate with (fCLK /fO) = 50:1 and sections A and D operate at 100:1. When Pin 17 is shorted to the negative supply pin, all filter sections operate with (fCLK /fO) = 100:1. 1µF NOTE: PINS 5, 8, 20, IF NOT USED, SHOULD BE CONNECTED TO PIN 6 6 U U U 1 2 V+ 3 4 5k V+/2 5 6 7 5k 0.1µF 8 9 10 ANALOG GROUND PLANE 11 12 AGND V+ LTC1064 24 23 22 21 20 19 V– CLK 50/100 18 17 16 15 14 13 TO DIGITAL GROUND CLOCK INPUT V + = 15V, TRIP VOLTAGE = 7V V + = 10V, TRIP VOLTAGE = 6.4V V + = 5V, TRIP VOLTAGE = 3V + 1064 F01 Figure 1. Single Supply Operation LTC1064 APPLICATIONS INFORMATION ANALOG CONSIDERATIONS Grounding and Bypassing The LTC1064 should be used with separated analog and digital ground planes and single point grounding techniques. Pin 6 (AGND) should be tied directly to the analog ground plane. Pin 7 (V +) should be bypassed to the ground plane with a 0.1µF ceramic capacitor with leads as short as possible. Pin 19 (V –) should be bypassed with a 0.1µF ceramic capacitor. For single supply applications, V – can be tied to the analog ground plane. For good noise performance, V + and V – must be free of noise and ripple. All analog inputs should be referenced directly to the single point ground. The clock inputs should be shielded from and/or routed away from the analog circuitry and a separate digital ground plane used. Figure 2 shows an example of an ideal ground plane design for a two-sided board. Of course this much ground plane will not always be possible, but users should strive to get as close to this as possible. Protoboards are not recommended. Buffering the Filter Output When driving coaxial cables and 1× scope probes, the filter output should be buffered. This is important especially when high Qs are used to design a specific filter. Inadequate buffering may cause errors in noise, distortion, Q and gain measurements. When 10 × probes are used, buffering is usually not required. An inverting buffer is recommended especially when THD tests are performed. As shown in Figure 3, the buffer should be adequately bypassed to minimize clock feedthrough. 1 2 3 4 5 6 7.5V 7 8 0.1µF CERAMIC 9 10 ANALOG GROUND PLANE 11 12 PIN 1 IDENT Figure 2. Example Ground Plane Breadboard Technique for LTC1064 U W U U 24 23 22 21 5k VIN FOR BEST HIGH FREQUENCY RESPONSE PLACE RESISTORS PARALLEL TO DOUBLESIDED COPPER CLAD BOARD AND LAY FLAT (4 RESISTORS SHOWN HERE TYPICAL) LTC1064 20 19 18 17 16 15 14 13 –7.5V 0.1µF CERAMIC CLOCK DIGITAL GROUND PLANE (SINGLE POINT GROUND) NOTE: CONNECT ANALOG AND DIGITAL GROUND PLANES AT A SINGLE POINT AT THE BOARD EDGE 1064 F02 7 LTC1064 APPLICATIONS INFORMATION Offset Nulling Lowpass filters may have too much DC offset for some users. A servo circuit may be used to actively null the offsets of the LTC1064 or any LTC switched-capacitor filter. The circuit shown in Figure 4 will null offsets to better than 300µV. This circuit takes seconds to settle because of the integrator pole frequency. SEPARATE V + POWER SUPPLY TRACE FOR BUFFER R12 R11 VIN R21 R31 R22 R32 10k V + TRACE FOR FILTER LTC1064 POSITIVE SUPPLY 0.1µF NEGATIVE SUPPLY 0.1µF 7 19 0.1µF 10k 0.1µF Figure 3. Buffering the Output of a 4th Order Bandpass Realization ODES OF OPERATIO PRIMARY MODES Mode 1 In Mode 1, the ratio of the external clock frequency to the center frequency of each 2nd order section is internally fixed at 50:1 or 100:1. Figure 5 illustrates Mode 1 providing 2nd order notch, lowpass and bandpass outputs. Mode 1 can be used to make high order Butterworth lowpass filters; it can also be used to make low Q notches and for cascading 2nd order bandpass functions tuned at the same center frequency with unity gain. Mode 1 is faster than Mode 3. Note that Mode 1 can only be implemented with three of the four LTC1064 sections because Section D has no externally available summing node. Section D, however, can be internally connected in Mode 1 upon special request. R3 R2 N R1 VIN S BP LP 8 U U W U U Noise All the noise performance mentioned excludes the clock feedthrough. Noise measurements will degrade if the already described grounding bypassing and buffering techniques are not practiced. The graph Wideband Noise vs Q in the Typical Performance Characteristics section is a very good representation of the noise performance of this device. + 1µF FROM FILTER OUTPUT – + 4 TO FILTER FIRST SUMMING NODE R3 100k LT ®318 LT1007 LT1056 7 R1 1M + LT1012 C1 0.1µF – R2 1M + 1µF C1 = C2 = LOW LEAKAGE FILM (I.E. POLYPROPYLENE) R1 = R2 = METAL FILM 1% 1064 F03 C2 0.1µF 1064 F04 Figure 4. Servo Amplifier W – + + Σ – ∫ ∫ 1/4 LTC1064 AGND fO = R2 R3 R2 R3 fCLK ; f n = fO; HOLP = – ;H =– ;H =– ;Q= R1 OBP R1 ON1 R1 R2 100(50) 1064 F05 Figure 5. Mode 1: 2nd Order Filter Providing Notch, Bandpass and Lowpass LTC1064 ODES OF OPERATIO Mode 3 Mode 3 is the second of the primary modes. In Mode 3, the ratio of the external clock frequency to the center frequency of each 2nd order section can be adjusted above or below 50:1 or 100:1. Side D of the LTC1064 can only be connected in Mode 3. Figure 6 illustrates Mode 3, the classical state variable configuration, providing highpass, bandpass and lowpass 2nd order filter functions. Mode 3 is slower than Mode 1. Mode 3 can be used to make high order all-pole bandpass, lowpass, highpass and notch filters. When the internal clock-to-center frequency ratio is set at 50:1, the design equations for Q and bandpass gain are different from the 100:1 case. This was done to provide speed without penalizing the noise performance. CC R4 R3 R2 HP R1 VIN S BP LP – + + Σ – 1/4 LTC1064 AGND MODE 3 (100:1): f fO = CLK 100 MODE 3 (50:1): R2 R3 R2 R2 ;Q= ; H OHP = – ; R4 R2 R4 R1 R3 R4 HOBP = – ;H =– R1 OLP R1 R2 1.005 R4 f R2 fO = CLK ;Q= ; R2 R2 50 R4 – R3 16R4 √ √ √ √ HOHP = – R2 ;H =– R1 OBP R3 R4 R1 ; H OLP = – R3 R1 1– 16R4 NOTE: THE 50:1 EQUATIONS FOR MODE 3 ARE DIFFERENT FROM THE EQUATIONS FOR MODE 3 OPERATIONS OF THE LTC1059, LTC1060 AND LTC1061. START WITH fO, CALCULATE R2/R4, SET R4; FROM THE Q VALUE, CALCULATE R3: R3 = 1.005 Q R2 √ ; THEN CALCULATE R1 TO SET R2 + R2 THE DESIRED GAIN. R4 16R4 Figure 6. Mode 3: 2nd Order Filter Providing Highpass, Bandpass and Lowpass U SECONDARY MODES Mode 1b Mode 1b is derived from Mode 1. In Mode 1b, Figure 7, two additional resistors R5 and R6 are added to alternate the amount of voltage fed back from the lowpass output into the input of the SA (or SB or SC) switched-capacitor summer. This allows the filter’s clock-to-center frequency ratio to be adjusted beyond 50:1 or 100:1. Mode 1b maintains the speed advantages of Mode 1. R6 R3 R2 N R1 VIN S BP LP R5 W – + + Σ – ∫ ∫ 1064 F07 1/4 LTC1064 AGND fO = fCLK 100(50) √R5R6R6; f + n = fO; Q = R3 R2 √R5R6R6 ; + R2 R1 ; R6 R5 + R6 1064 F07 Eq ∫ ∫ 1064 F06 R2 f HON1(f→ 0) = HON2 f→ CLK = – ;H =– R1 OLP 2 R3 ; R5 R6 ≤ 5k  R1 ( ) HOBP = – Figure 7. Mode 1b: 2nd Order Filter Providing Notch, Bandpass and Lowpass Mode 2 Mode 2 is a combination of Mode 1 and Mode 3, as shown in Figure 8. With Mode 2, the clock-to-center frequency ratio fCLK /fO is always less than 50:1 or 100:1. The advantage of Mode 2 is that it provides less sensitivity to resistor tolerances than does Mode 3. As in Mode 1, Mode 2 has a notch output which depends on the clock frequency and the notch frequency is therefore less than the center frequency fO. 1064 F06 Eq When the internal clock-to-center frequency ratio is set at 50:1, the design equations for Q and bandpass gain are different from the 100:1 case. 9 LTC1064 ODES OF OPERATIO R4 R3 R2 N R1 S VIN – + + Σ – 1/4 LTC1064 AGND Figure 8. Mode 2: 2nd Order Filter Providing Notch, Bandpass and Lowpass Mode 3a This is an extension of Mode 3 where the highpass and lowpass outputs are summed through two external resistors RH and RL to create a notch. This is shown in Figure 9. Mode 3a is more versatile than Mode 2 because the notch frequency can be higher or lower than the center frequency of the 2nd order section. The external op amp of Figure 9 is not always required. When cascading the sections of the LTC1064, the highpass and lowpass out- CC R4 R3 MODE 3a (50:1): R2 HP R1 VIN S – + AGND + Σ – ∫ RH 1/4 LTC1064 Figure 9. Mode 3a: 2nd Order Filter Providing Highpass, Bandpass, Lowpass and Notch 10 U MODE 2 (100:1): f fO = CLK 100 W √ 1+ f R3 R2 ; f = CLK ; Q = 50 R2 R4 n √ √ 1+ R2 ; HOLP = – R4 BP LP R2 R2 R3 f R1 HOBP = – ; H (f→ 0) = – ; HON2 f→ CLK = – R1 R1 ON1 2 R2 1+ R4 f fO = CLK 50 ( ) R2 R1 ; R2 1+ R4 ∫ ∫ 1064 F08 MODE 2 (50:1): √ 1+ R2 R2 1.005 1 + R2 f R1 R4 ; H ; fn = CLK ; Q = =– ; OLP R4 50 R2 R2 R2 1+ – R3 16R4 R4 HOBP = – R3 R2 f R2 R1 R1 ; HON1(f→ 0) = – ;H = f→ CLK = – 2 R3 R1 R2 ON2 1– 1+ 16R4 R4 ( ) NOTE: THE 50:1 EQUATIONS FOR MODE 2 ARE DIFFERENT FROM THE EQUATIONS FOR MODE 2 OPERATION OF THE LTC1059, LTC1060 AND LTC1061. START WITH fO, CALCULATE R2/R4, SET R4; FROM THE Q VALUE, CALCULATE R3: R3 = 1.005 Q R2 R2 √1 + R2 + 16R4 R4 ; THEN CALCULATE R1 TO SET THE DESIRED GAIN. 1064 F08Eq puts can be summed directly into the inverting input of the next section. The topology of Mode 3a is useful for elliptic highpass and notch filters with clock-to-cutoff frequency ratios higher than 100:1. This is often required to extend the allowed input signal frequency range and to avoid premature aliasing. When the internal clock-to-center frequency ratio is set at 50:1, the design equations for Q and bandpass gain are different from the 100:1 case. MODE 3a (100:1): f fO = CLK 100 HOLP = – √ R2 ; f = 100 √ R ; H R4 n fCLK RH L OHP = – RG R2 R R4 R4 f ; H (f→ 0) = G ;H f→ CLK = ; RH R1 RL R1 ON2 R1 ON1 2 HON(f = fO) = Q f fO = CLK 50 ( R RG R3 H – GH ;Q= RL OLP RH OHP R2 n CLK BP LP RL RG HOBP = – √1 + R2 ; f = f50 R4 ( )( ) ( ) ( √ R3 R2 ; HOBP = – ; R1 R1 ) ( )( ) √ R2 R4 R2 f RH ; ; HOHP f→ CLK = – R1 2 RL ) ∫ – NOTCH R3 R2 1.005 R4 R1 R4 ; HOLP(f = 0) = – ;Q = R3 R1 R2 R2 1– – 16R4 R3 16R4 √ + EXTERNAL OP AMP OR INPUT OP AMP OF THE LTC1064, SIDE A, B, C, D NOTE: THE 50:1 EQUATIONS FOR MODE 3A ARE DIFFERENT FROM THE EQUATIONS FOR MODE 3A OPERATION OF THE LTC1059, LTC1060 AND LTC1061. START WITH fO, CALCULATE R2/R4, SET R4; FROM THE Q VALUE, CALCULATE R3: R2 R3 = ; THEN CALCULATE R1 TO 1.005 Q R2 √ R2 + 16R4 SET THE DESIRED GAIN. R4 1064 F09Eq 1064 F09 LTC1064 TYPICAL APPLICATIONS Wideband Bandpass: Ratio of High to Low Corner Frequency Equal to 2 R14 15 1 R23 R33 R43 2 3 4 5 C1 5V TO 8V 0.1µF R41 R31 R21 R11 VIN R13 6 7 8 9 10 11 12 INV B HPB/NB BPB LPB SB AGND V+ SA LPA BPA HPA/NA INV A LTC1064 LPC SC V– CLK 20 19 18 17 16 15 14 13 R42 R32 R22 R12 C2 fCLK ≤ 7MHz VOUT –5V TO –8V GAIN (dB) RESISTOR VALUES: R11 = 16k R21 = 16k R31 = 7.32k R41 = 10k R12 = 10k R22 = 10k R32 = 22.6k R42 = 13.3k R13 = 23.2k R23 = 13.3k R33 = 21.5k R43 = 10k R14 = 6.8k R24 = 20k R34 = 15.4k R44 = 32.4k NOTE: FOR fCLK ≥ 3MHz, USE C1 = C2 = 22pF Quad Bandpass Filter with Center Frequency Equal to fO, 2fO, 3fO, and 4fO 10.5k R12 VIN1 R22 R32 5 1 2 3 4 5 6 INV B HPB/NB BPB LPB SB AGND V+ SA LPA BPA HPA/NA INV A LTC1064 INV C HPC/NC BPC LPC SC V– CLK GAIN (dB) 5V TO 8V 0.1µF R31 R21 R11 VIN3 7 8 9 10 11 12 50/100 LPD BPD HPD INV D RESISTOR VALUES: R11 = 249k R21 = 10k R12 = 249k R22 = 10k R13 = 499k R23 = 10k R14 = 453k R24 = 10k R31 = 249k R32 = 249k R33 = 174k R34 = 249k U Amplitude Response INV C HPC/NC BPC 24 23 22 21 R24 R34 R44 0 –15 –30 –45 fCLK = 2MHz –60 –75 –90 –105 10k VS = ± 8V fCLK = 7MHz 0.1µF 50/100 LPD BPD HPD INV D 100k INPUT FREQUENCY (Hz) 1M 1064 TA04 1064 TA03 Amplitude Response 24 23 22 21 20 19 18 17 16 15 14 13 17.4k 20k 20k R44 R34 R24 fCLK R23 R33 R43 R13 VIN2 0 –5 –10 –15 –20 –25 –30 –35 –40 0 fCLK = 2MHz –5V TO –8V 0.1µF 10 20 30 40 50 1064 TA06 INPUT FREQUENCY (kHz) R14 VIN4 20k – LT1056 VOUT + R43 = 17.8k R44 = 40.2k 1064 TA05 11 LTC1064 TYPICAL APPLICATIONS 8th Order Bandpass Filter with 2 Stopband Notches RL2 10 R12 R22 R32 R42 1 2 3 4 5 6 INV B HPB/NB BPB LPB SB AGND V+ SA LPA BPA HPA/NA INV A LTC1064 BPC LPC SC V– CLK 22 21 20 19 18 17 16 15 14 13 R33 R43 RL3 GAIN (dB) 5V TO 8V 0.1µF R41 R31 R21 R11 VIN RESISTOR VALUES: R11 = 46.95k R21 = 10k R12 = 93.93k R22 = 10k R23 = 16.3k R24 = 13.19k 7 8 9 10 11 12 R31 = 38.25k R32 = 81.5k R33 = 70.3k R34 = 39.42k NOTE1: THE V +, V – PINS SHOULD BE BYPASSED WITH A 0.1µF TO 0.22µF CERAMIC CAPACITOR, RIGHT AT THE PINS. NOTE 2: THE RATIOS OF ALL (R2/R4) RESISTORS SHOULD BE MATCHED TO BETTER THAN 0.25%. THE REMAINING RESISTORS SHOULD BE BETTER THAN 0.5% ACCURATE. C-Message Filter R13 1 R22 R32 R42 2 3 4 5 6 5V 7 R12 0.1µF R41 R31 R21 R11 VIN RESISTOR VALUES: R11 = 88.7k R21 = 10k R12 = 10k R22 = 44.8k R13 = 15.8k R23 = 48.9k R14 = 15.8k R24 = 44.8k 8 9 10 11 12 INV B HPB/NB BPB LPB SB AGND V+ SA LPA BPA HPA/NA INV A LTC1064 INV C HPC/NC BPC LPC SC V– CLK 24 23 22 21 20 19 18 17 16 15 14 13 VOUT R31 = 35.7k R32 = 33.2k R33 = 63.5k R34 = 16.5k R41 = 88.7k R42 = 24.9k R43 = 25.5k R44 = 24.9k R44 R34 R24 R23 R33 GAIN (dB) 12 U Amplitude Response RH2 RH3 INV C HPC/NC 24 23 R23 –20 –30 –40 –50 –60 0 –10 VS = ± 5V fCLK = 1.28MHz PIN 17 AT V + –5V TO –8V 1.28MHz R44 R34 R24 0.1µF TO V + 50/100 LPD BPD HPD INV D –70 1 5 10 20 40 INPUT FREQUENCY (kHz) 100 1064 TA08 VOUT R41 = 11.81k R42 = 14.72k R L2 = 27.46k R H2 = 6.9k R43 = 10k R L3 = 17.9k R H3 = 69.7k R44 = 10.5k 1064 TA07 Amplitude Response 10 0 –10 –20 –30 –40 –50 –60 –70 0 1 3 2 4 INPUT FREQUENCY (kHz) 5 1064 TA10 VS = ± 5V R43 R14 0.1µF –5V fCLK = 3.5795MHz 16 50/100 LPD BPD HPD INV D 1064 TA09 LTC1064 TYPICAL APPLICATIONS 8th Order Chebyshev Lowpass Filter with a Passband Ripple of 0.1dB and Cutoff Frequency up to 100kHz R13 1 R22 R32 R12 R42 2 3 4 5 6 5V TO 8V 7 0.1µF R41 R31 R21 R11 VIN 8 9 10 11 12 INV B HPB/NB BPB LPB SB AGND V+ SA LPA BPA HPA/NA INV A LTC1064 SC V 20 R14 –5V TO –8V fCLK = 5MHz 5V TO 8V R44 R34 R24 0.1µF GAIN (dB) RESISTOR VALUES: R11 = 100.86k R21 = 16.75k R12 = 25.72k R22 = 20.93k R13 = 16.61k R23 = 10.18k R14 = 13.84k R24 = 11.52k R31 = 23.6k R32 = 45.2k R33 = 68.15k R34 = 17.72k FOR fCLK > 3MHz, ADD C2 = 10pF ACROSS R42 C3 = 10pF ACROSS R43 C4 = 10pF ACROSS R44 WIDEBAND NOISE = 170µVRMS 8th Order Clock-Sweepable Lowpass Elliptic Antialiasing Filter RH1 RL1 RH2 RL2 1 R22 R32 R42 2 3 4 5 6 7.5V 0.1µF R43 R33 R23 7 8 9 10 11 12 INV B HPB/NB BPB LPB SB AGND V+ SA LPA BPA HPA/NA INV A LTC1064 INV C HPC/NC BPC LPC SC V– CLK 24 23 22 21 20 19 18 17 16 15 14 13 RL3 RH3 RESISTOR VALUES: R11 = 19.1k R21 = 10k R22 = 10k R23 = 11.3k R24 = 15.4k VOUT fCLK ≤ 2MHz –7.5V R44 R34 R24 0.1µF R21 R31 R41 R11 VIN VOUT/VIN (dB) 50/100 LPD BPD HPD INV D R31 = 13.7k R32 = 23.7k R33 = 84.5k R34 = 15.2k R41 = 15.4k R42 = 10.2k R43 = 10k R44 = 42.7k NOTE: FOR tCUTOFF >15kHz, ADD A 5pF CAPACITOR ACROSS R41 AND R43 U Amplitude Response 15 INV C HPC/NC BPC LPC 24 23 22 21 R23 R33 R43 0 –15 –30 –45 –60 –75 –90 VS = ± 8V fCLK = 5MHz PASSBAND RIPPLE = 0.1dB 100k INPUT FREQUENCY (Hz) 1M 1064 TA12 – 19 CLK 18 17 16 15 14 13 50/100 LPD BPD HPD INV D –105 10k VOUT R41 = 99.73k R42 = 25.52k R43 = 99.83k R44 = 25.42k 1064 TA11 Amplitude Response 0 –15 –30 –45 –60 –75 –90 –7.5V –105 0 10 20 30 40 50 60 70 FREQUENCY (kHz) 8TH ORDER CLOCK-SWEEPABLE LOWPASS ELLIPTIC ANTIALIASING FILTER MAINTAINS, FOR 0.1Hz ≤ fCUTOFF ≤ 20kHz, A ± 0.1dB MAX PASSBAND ERROR AND 72dB MIN STOPBAND ATTENUATION AT 1.5 × fCUTOFF. TOTAL WIDEBAND NOISE = 150µVRMS, THD = 70dB (0.03%) FOR VIN = 3VRMS, fCLK /fCUTOFF = 100:1. THIS FILTER AVAILABLE AS LTC1064-1 WITH INTERNAL THIN FILM 1064 TA14 RESISTORS. R H1 = 30.9k R L1 = 14k R L2 = 26.7k R H2 = 76.8k R H3 = 60.2k R L3 = 10k 1064 TA13 13 LTC1064 TYPICAL APPLICATIONS Dual 4th Order Bessel Filter with 140kHz Cutoff Frequency R13 R12 VIN1 R22 R32 R42 1 2 3 4 5 6 8V 0.1µF 7 8 9 R41 R31 R11 VIN2 R21 10 11 12 INV B HPB/NB BPB LPB SB AGND V+ SA LPA BPA HPA/NA INV A LTC1064 INV C HPC/NC BPC LPC SC V– 24 23 22 21 20 19 R23 R33 15 0 – 15 GAIN (dB) 18 7MHz CLK CLOCK 17 50/100 8V 16 LPD R44 15 BPD R34 14 HPD R24 13 INV D R14 RESISTOR VALUES: R11 = 14.3k R21 = 13k R12 = 15.4k R22 = 15.4k R13 = 3.92k R23 = 20k R14 = 3.92k R24 = 20k R31 = 7.5k R32 = 7.5k R33 = 27.4k R34 = 6.8k WIDEBAND NOISE = 64µVRMS 8th Order Linear Phase (Bessel) Filter with R11 VIN1 R21 R31 R41 1 2 3 4 5 6 INV B HPB/NB BPB LPB SB AGND V+ SA LPA BPA HPA/NA INV A LTC1064 HPC/NC BPC LPC SC GAIN (dB) 5V TO 8V 0.1µF 7 8 9 R43 R33 10 11 12 FROM PIN 20 R13 R23 RESISTOR VALUES: R11 = 34.8k R21 = 34.8k R12 = 10.5k R22 = 45.3k R13 = 12.7k R23 = 34.8k R14 = 20k R24 = 34.8k R31 = 14.3k R32 = 22.1k R33 = 24.3k R34 = 13.3k WIDEBAND NOISE = 70µVRMS 14 U Amplitude Response R43 VOUT1 –8V 0.1µF VOUT2 –30 –45 –60 –75 –90 VS = ± 8V fCLK = 7MHz 100k INPUT FREQUENCY (Hz) 1M 1064 TA16 –105 10k R41 = 10k R42 = 10k R43 = 40k R44 = 10k 1064 TA15 fCLK 65 = f –3dB 1 R12 15 0 – 15 –30 –45 –60 –75 –90 –105 10k Amplitude Response INV C 24 23 22 21 20 R22 R32 R42 TO R13 fCLK ≤ 7MHz TO V + R44 R34 R24 R14 –5V TO –8V 0.1µF VOUT 19 V– CLK 18 17 16 15 14 13 50/100 LPD BPD HPD INV D VS = ± 8V fCLK = 4.5MHz fCLK = 50% DUTY CYCLE f–3dB = 70kHz 100k INPUT FREQUENCY (Hz) 1M 1064 TA18 R41 = 40.2k R42 = 39.2k R43 = 20k R44 = 20k 1064 TA17 LTC1064 TYPICAL APPLICATIONS Dual 5th Order Chebyshev Lowpass Filter with 50kHz and 100kHz Cutoff Frequencies R14 R13a VIN2 R13b C2 1000pF R23 R33 R43 1 2 3 4 5 2pF 6 7 0.1µF 22pF 8 9 R41 R31 R11a VIN1 R11b C1 1000pF R21 10 11 12 INV B HPB/NB BPB LPB SB AGND V+ SA LPA BPA HPA/NA INV A LTC1064 INV C HPC/NC BPC LPC SC V– CLK 24 23 22 21 20 19 18 17 16 15 14 13 R12 5MHz T 2L R42 R32 R22 39pF RESISTOR VALUES: R11a = 4.32k R21 = 11.8k R11b = 27.4k R22 = 20k R12 = 10.5k R23 = 11.8k R13a = 3k R24 = 20k R13b = 29.4k R14 = 10.5k R31 = 29.4k R32 = 21.5k R33 = 29.4k R34 = 21.6k R41 = 10k R42 = 31.6k R43 = 10k R44 = 31.6k 1064 TA19 4pF R44 VOUT2 fC = 100kHz –8V 0.1µF VOUT1 fC = 50kHz GAIN (dB) 8V Clock-Tunable, 30kHz to 90kHz 8th Order Notch Filter Providing Notch Depth in Excess of 60dB R13 C2 1 R22 R32 R42 2 3 4 5 C1 8V 0.1µF R12 R31 R21 R11 VIN1 6 7 8 9 10 11 12 24 23 22 21 R23 R33 R14 INV B HPB/NB BPB LPB SB AGND V+ SA LPA BPA HPA/NA INV A LTC1064 INV C HPC/NC BPC LPC SC V– CLK GAIN (dB) RESISTOR VALUES: R11 = 50k R21 = 5k R12 = 15.4k R22 = 10k R13 = 10k R23 = 10k R14 = 9.09k R24 = 10k R31 = 50k R32 = 88.7k R33 = 100k R34 = 63.4k R42 = 48.7k R44 = 12.4k RELATED PARTS PART NUMBER LTC1061 LTC1164 LTC1264 DESCRIPTION Triple Universal Filter Building Block Low Power, Quad Universal Filter Building Block High Speed, Quad Universal Building Block COMMENT Three Filter Building Blocks in a 20-Pin Package Low Noise, Low Power Pin-for-Pin LTC1064 Compatible Up to 250kHz Center Frequency 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. U Amplitude Response 15 PASSBAND RIPPLE = 0.2dB 0 R24 R34 – 15 –30 –45 –60 –75 –90 –105 10k 50k 100k INPUT FREQUENCY (Hz) 1M 1064 TA20 50/100 LPD BPD HPD INV D Amplitude Response 10 0 –10 –20 0.1µF BW 20 19 18 17 16 15 14 13 R44 R34 R24 RL4 0.1% RH4 0.1% C3 –8V –30 –40 –50 –60 –70 –80 –90 VS = ± 8V fCLK = 4MHz 10 20 30 40 50 60 INPUT FREQUENCY (kHz) 70 fCLK ≤ 5MHz 50/100 LPD BPD HPD INV D C1 = C2 = C3 = 15pF THE NOTCH DEPTH FROM 5kHz TO 30kHz IS 50dB WIDEBAND NOISE = 300µVRMS RG –100 –110 1064 TA22 – LT1056 VOUT R G = 68.1k R L4 = 10k (0.1%) R H4 = 10k (0.1%) + 1064 TA21 15 LTC1064 PACKAGE DESCRIPTION U Dimension in inches (millimeters) unless otherwise noted. 1.290 (32.77) MAX 24 23 22 21 20 19 18 17 16 15 14 13 CORNER LEADS OPTION (4 PLCS) 0.023 – 0.045 (0.584 – 1.143) HALF LEAD OPTION 0.220 – 0.310 0.025 (5.588 – 7.874) (0.635) RAD TYP 1 11 J Package 24-Lead Ceramic DIP 0.045 – 0.068 (1.143 – 1.727) FULL LEAD OPTION 0.300 BSC (0.762 BSC) 2 0.005 (0.127) MIN 3 4 5 6 7 8 9 10 12 0.200 (5.080) MAX 0.015 – 0.060 (0.381 – 1.524) 0.008 – 0.018 (0.203 – 0.457) 0° – 15° 0.385 ± 0.025 (9.779 ± 0.635) 0.125 (3.175) MIN 0.045 – 0.068 (1.143 – 1.727) 0.014 – 0.026 (0.360 – 0.660) 1.265* (32.131) 0.100 ± 0.010 (2.540 ± 0.254) J24 0695 NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE OR TIN PLATE LEADS. 24 23 22 21 20 19 18 17 16 15 14 13 0.255 ± 0.015* (6.477 ± 0.381) N Package 24-Lead Plastic DIP 1 0.300 – 0.325 (7.620 – 8.255) 0.130 ± 0.005 (3.302 ± 0.127) 0.015 (0.381) MIN 0.009 – 0.015 (0.229 – 0.381) 2 3 4 5 6 7 8 9 10 11 12 0.045 – 0.065 (1.143 – 1.651) 0.065 (1.651) TYP 0.018 ± 0.003 (0.457 ± 0.076) N24 0695 0.005 (0.127) MIN +0.635 8.255 0.100 ± 0.010 –0.381 (2.540 ± 0.254) *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm) ( +0.025 0.325 –0.015 ) 0.125 (3.175) MIN 24 23 22 21 0.598 – 0.614 (15.190 – 15.600) (NOTE 2) 20 19 18 17 16 15 14 13 NOTE: 1. PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS. THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS. * DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE NOTE 1 0.394 – 0.419 (10.007 – 10.643) SW Package 24-Lead Plastic SO ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 0.291 – 0.299 (7.391 – 7.595) (NOTE 2) 0.010 – 0.029 × 45° (0.254 – 0.737) 0° – 8° TYP 1 0.093 – 0.104 (2.362 – 2.642) 2 3 4 5 6 7 8 9 10 11 12 0.037 – 0.045 (0.940 – 1.143) 0.009 – 0.013 (0.229 – 0.330) NOTE 1 0.016 – 0.050 (0.406 – 1.270) 0.050 (1.270) TYP 0.004 – 0.012 (0.102 – 0.305) SW24 0695 0.014 – 0.019 (0.356 – 0.482) 16 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7487 (408) 432-1900 q FAX: (408) 434-0507 q TELEX: 499-3977 LT/GP 0895 2K REV A • PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 1989