KR Electronics, Inc. KR 2388 Root Raised Cosine Filter www.krfilters.com General Description Features • Root raised cosine response • Closely matches the ideal response • Sin(x)/x available • Equalized for linear phase • Supplied in phase matched pairs KR Electronics designs and manufactures filters that approximate the raised cosine response. These filters are available as both the cosine response and the root cosine response. Symbol rates to 75 MHz have been designed. They are also available with and without sin(x)/x compensation. Various roll off factors alpha (α) are also available. Typical values for α fall in the 0.3 to 0.5 range. KR’s filters closely match the mathematical ideal response to the –12 dB frequency and are most often designed for linear phase to the –3 dB response. Phase matching in pairs is also commonly specified. KR 2388 is a root raised cosine filter without sin(x)/x compensation, Fs=2 MHz and α=0.35. The typical response of KR 2388 root raised cosine is shown in the plots below. Typical Performance Figure 1 shows the ideal response, while Figures 2-6 show actual measured data from a typical filter. Ideal Response Actual Filter Response (5 dB/div) 0.1 to 1.5 MHz (5 dB/div) 0.1 to 1.5 MHz 18 Jan 2001 09:47:08 CH1 MEM LOG 5 dB/ 18 Jan 2001 09:47:33 REF 0 dB CH1 PRm PRm Cor Cor START . 100 000 MHz STOP Figure 1 © 2001, KR Electronics, Inc. 1 . 500 000 MHz S31 LOG START 5 dB/ . 100 000 REF -.75 dB MHz STOP 1 . 500 000 MHz Figure 2 Page 1 KR Electronics, Inc. www.krfilters.com KR 2388 Root Raised Cosine Filter Typical Performance (cont.) Deviation From Ideal Response Overall Frequency Response (1 dB/div) .1 to 1.5 MHz (10 dB/div) .1 to 10 MHz 18 Jan 2001 09:49:58 CH1 S31 /M LOG 1 dB/ REF -.75 dB 1 : - . 65550 dB 18 Jan 2001 09:41:16 1 . 245 000 MHz CH1 PRm PRm Cor Cor S31 LOG 10 dB/ REF -40 dB SCALE 10 dB/div 1 START . 100 000 MHz STOP 1 . 500 000 MHz START . 100 000 MHz STOP Figure 3 PRm Del Cor S31 000 Deviation From Linear Phase Phase Match Between Pairs (2°/div) .1 to 1.5 MHz (2°/div) .1 to 1.5 MHz 18 Jan 2001 09:52:40 CH1 10 . 000 PHA 2 / MHz Figure 4 18 Jan 2001 09:54:39 REF 0 CH1 S31 /M PHA 2 / REF 0 1 : 1 . 0526 . 870 000 MHz PRm SCALE 2 /div Cor SCALE 2 /div 1 START . 100 000 MHz STOP Figure 5 © 2001, KR Electronics, Inc. 1 . 000 000 MHz START . 100 000 MHz STOP 1 . 000 000 MHz Figure 6 Page 2 KR Electronics, Inc. www.krfilters.com KR 2388 Root Raised Cosine Filter Specifications Parameter Specification Filter type Root Raised Cosine Rolloff factor (α) 0.35 Fs 2 MHz Source and load impedance 50 Ω Deviation from ideal < ± 1 dB to the –12 dB frequency Deviation from linear phase <± 2.5° to the –3 dB frequency Phase match in pairs <± 2.5° to the –1 dB frequency Physical Dimensions KR Electronics, Inc. 91 Avenel Street Avenel, NJ 07001 © 2001, KR Electronics, Inc. Web Email Phone Fax www.krfilters.com [email protected] (732) 636-1900 (732) 636-1982 Page 3