ZXF103 VARIABLE Q FILTER DESCRIPTION The ZXF103 is a versatile analog high Q bandpass filter. It can be configured to provide pass or notch characteristics. The basic filter section requires 2 resistors and 2 capacitors to set the centre frequency. The frequency range is up to 600kHz. Two external resistors control filter Q Factor. The Q can be varied up to 50. APPLICATIONS FEATURES AND BENEFITS Many filter applications including: - • Centre Frequency up to 1MHz • Sonar and Ultrasonic Systems • Variable Q up to 50 • Line frequency notch • Low distortion • Signalling • Low noise • Motion detection • Low power 25mW • Instrumentation • Devices easily cascaded • Low frequency telemetry • Small QSOP16 package ORDERING INFORMATION PART NUMBER PACKAGE PART MARK ZXF103Q16 QSOP16 ZXF103 Filter Input C R ZXF103 R CONTAINER INCREMENT ZXF103Q16TA Reel 7” 178mm 500 ZXF103Q16TC Reel 13” 330mm 2500 PINOUT 1 R2 0V RC2 BIAS RC1 0V C1 FI1 SYSTEM DIAGRAM R PART NUMBER C Filter Output Q SET ISSUE 1 - APRIL 2002 1 16 GP1 Vcc GP3 GP2 NC Vcc FO FI2 ZXF103 ABSOLUTE MAXIMUM RATINGS Voltage on any pin Operating temperature range Storage temperature 7.0V (relative to 0V) 0 to 70°C -55 to 125°C ELECTRICAL CHARACTERISTICS Test Coνditions: Temperature =25°C, VCC = 5.00V, 0V =0.00V, RL=10k,CL=10pF GENERAL CHARACTERISTICS Parameter Conditions Min. Operating current Max. operating frequency Typical Max. 4.0 5.0 mA 600 1000 kHz Vout=1.6V p-p Vout=1.0V p-p Q usable range 0.5 Units 50 Centre Frequency temperature coefficient Q=30, fo = 1kHz 100 ppm/°C Q temperature coefficient Q=30, fo = 1kHz 0.1 % /°C Voltage noise 1 – 100 kHz 20 Input impedance 10 Output load =10 kΩ Linear Output Range 15 nV/√ Hz 20 kΩ 2 V pk-pk Sink current 450 µA Source current 450 µA Number of Devices Histogram of Centre Frequency (Fo = 11.80KHz Q = 25) 11.78 11.79 11.80 Frequency (KHz) 11.81 11.82 Pin Name Function 1 R2 Phase retard node 2 0V 0 Volts 3 RC2 Phase retard node 4 BIAS Internal bias generator 5 RC1 Phase advance node 6 0V 0 Volts 7 C1 Phase advance node 8 FI1 Filter input mode dependent 9 FI2 Filter input, mode dependent 10 FO Filter output for all modes 11 Vcc +5 Volt supply 12 N/C No connection 13 GP2 Loop gain node 14 GP3 Loop gain node 15 Vcc +5 Volt supply 16 GP1 Loop gain node ISSUE 1 - APRIL 2002 2 ZXF103 Filter Configurations and Responses Notch Filter AC Filter Performance 0 Fo = Gain (dB) -8 1 2 πRC -16 where R=R1=R2 and C=C1=C2 -24 Q ∝ -32 where R1,R2,R3 and R4 艌2kΩ and C1 and C2 艌 50pF -40 10K 100K 1M R4 R3 10M Frequency (Hz) 270 See “Designing for a value of Q” for more details. Phase (deg) 225 180 135 90 45 10K 100K 1M 10M Frequency (Hz) ISSUE 1 - APRIL 2002 3 ZXF103 Filter Configurations and Responses (Continued) Inverse Notch Filter (with 0dB Stop Band) AC Filter Performance Gain (dB) 30 1 2 πRC 24 Fo = 18 where R=R1=R2 and C=C1=C2 12 Q ∝ where R1,R2,R3 and R4 艌2kΩ and C1 and C2 艌 50pF 6 0 10K R4 R3 100K 1M 10M Frequency (Hz) -45 -90 -135 -180 -225 -270 10K 100K 1M 10M Frequency (Hz) ISSUE 1 - APRIL 2002 4 ZXF103 Filter Configurations and Responses (Continued) Inverse Notch Filter (with attenuating skirts) AC Filter Performance 30 Fo = Gain (dB) 20 10 1 2 πRC where R=R1=R2 and C=C1=C2 0 Q ∝ -10 -20 10K 100K 1M 10M R4 R3 where R1,R2,R3 and R4 艌2kΩ and C1 and C2 艌 50pF Frequency (Hz) See “Designing for a value of Q” for more details. -90 The skirt ‘roll off’ away from the peak is -20dB/Decade regardless of chosed Q. Phase (deg) -180 -270 Typical responses from the circuit with component values derived from the diagram. -360 -450 -540 10K 100K 1M 10M Frequency (Hz) ISSUE 1 - APRIL 2002 5 ZXF103 Frequency dependant effects must be accounted for in determining the appropriate gain. As the frequency increases, the effective circuit gain reduces. The required gain is nominally two but at higher frequencies it will need to be slightly greater than two in order to compensate for loss of gain and internal phase shifts. Designing for a value of Q As mentioned on the configuration pages, there is a proportional relationship between the ratio of R4 and R3, and Q. Q ∝ R4 R3 These resistors define the gain of an inverting amplifier that determines the peak value of gain and therefore the Q of the filter, as Q is described as; This is not really a problem for circuits where the desired Fo remains constant, as the phase shifts are accounted for permanently. For designs where Q is high and Fo is to be ‘swept’, care must be taken that a gain appropriate at the highest frequency does not cause oscillation at the lowest. Fo Q= −3dBBandwidth Variation in Q increases from device to device, as the value of Q increases, due to internal gain spreads. This value of required gain is quite critical. As the maximum value of Q is approached, too much gain will cause the filter to oscillate at the centre frequency Fo. A small reduction of gain will cause the value of Q to fall significantly. Therefore, for high values of Q factor or tight tolerances of lower values of Q, the resistor ratio must be trimmed. ISSUE 1 - APRIL 2002 6 ZXF103 Evaluation Board Schematic 0v C3 C4 100 nF 100 nF 5v C2 330 pF R1 6.8k R2 6.8 k 1 C1 330 pF R3 10 k R2 0v RC2 Bias RC1 0v C1 FI 1 GP1 Vcc GP3 GP2 N/C Vcc FO FI 2 VR1 2 k R4 22 k C5 Output 100 nF ZXF103 J1 J2 J3 C6 Input 100 nF The evaluation board is designed for operation at 70kHz. Notch Notch Pass 1 Notch Pass 2 J1 and J2 J2 and J3 (0dB Stop Band) J3 only (Attenuating skirts) ISSUE 1 - APRIL 2002 7 ZXF103 ISSUE 1 - APRIL 2002 8 ZXF103 QSOP16 DIM Millimetres Inches MIN MAX MIN MAX A 4.80 4.98 0.189 0.196 B 0.635 0.025 NOM C 0.23 REF 0.009 REF D 0.20 0.30 0.008 0.012 E 3.81 3.99 0.15 0.157 F 1.35 1.75 0.053 0.069 G 0.10 0.25 0.004 0.01 J 5.79 6.20 0.228 0.244 K 0° 8° 0° 8° Conforms to JEDEC MO-137AB Iss A © Zetex plc 2001 Zetex plc Fields New Road Chadderton Oldham, OL9 8NP United Kingdom Telephone (44) 161 622 4422 Fax: (44) 161 622 4420 Zetex Inc Suite 315 700 Veterans Memorial Highway Hauppauge NY11788 USA Telephone: (631) 360 2222 Fax: (631) 360 8222 Zetex GmbH Streitfeldstraße 19 D-81673 München Germany Telefon: (49) 89 45 49 49 0 Fax: (49) 89 45 49 49 49 Zetex (Asia) Ltd 3701-04 Metroplaza, Tower 1 Hing Fong Road Kwai Fong, Hong Kong China Telephone: (852) 26100 611 Fax: (852) 24250 494 These offices are supported by agents and distributors in major countries world-wide. This publication is issued to provide outline information only which (unless agreed by the Company in writing) may not be used, applied or reproduced for any purpose or form part of any order or contract or be regarded as a representation relating to the products or services concerned. The Company reserves the right to alter without notice the specification, design, price or conditions of supply of any product or service. For the latest product information, log on to www.zetex.com ISSUE 1 - APRIL 2002 9