Analog bandpass filter

• US 20040217827A1
• Filed: 06/01/2004
• Published: 11/04/2004
• Est. Priority Date: 12/03/2001
• Status: Abandoned Application

• Current Assignee: Diseño de Sistemas en Silicio SA (Marvell Technology Group Limited)
• Original Assignee: Diseño de Sistemas en Silicio SA (Marvell Technology Group Limited)
• Inventors: Poveda Lerma, Antonio, Vidal Ros, Jose Maria, Gonzalez Moreno, Jose Luis
• Application Number:
  US10/858,005
• Publication Number:
  US 20040217827A1
• Time in Patent Office: Days
• US Class Current: 333/175
• CPC Class Codes: H03H 7/0161 Bandpass filters H03H7/12 takes precedence
• CPC Class Codes: H03H 7/03 comprising means for compensation of loss
• CPC Class Codes: H03H 7/06 including resistors H03H7/075, H03H7/09, H03H7/12, H03H7/13 take precedence
• CPC Class Codes: H03H 7/075 Ladder networks, e.g. electric wave filters
• CPC Class Codes: H03H 7/1775 Parallel LC in shunt or branch path H03H7/1791 takes precedence
• CPC Class Codes: H03H 7/1783 Combined LC in series path

Abstract

The invention relates to an analog bandpass filter comprising a plurality of LC ladder circuits (1), the response from which is determined by a passband (fpi, fps) and a rejection band (with limits fri and frs). The inventive filter is characterised in that a series of tank circuits (5) is disposed in parallel to the filter charge, the resonance frequencies of said tank circuits coinciding with the lower (fpi) and upper (fps) cut-off frequency of the pass-band of the filter. Furthermore, the filter comprises a control resistor (Rc) which regulates the effect of the tank circuits on the filter. Said structure can be used to compensate the effect of the real limitations of the LC components (1) in order to adjust the response from the analog bandpass filter created with said components to the response from the ideal bandpass filter.

Claims

1. ANALOG BAND PASS FILTER comprising numerous LC ladder circuits whose response is defined by a pass band (f_ri and f_ps) and a stop band (whose limits are f_ri and f_rs);

wherein the LC ladder circuits include in parallel with the filter load, a series of tank circuits whose resonance frequencies coincide with lower (f_pi) and upper (f_ps) cut frequencies of the bandpass filter;

where furthermore a control resistance R_c is foreseen, all of which is to compensate for effect of a real limitation of LC components by adjusting a real response of the bandpass filter to an ideal response desired.

2. ANALOG BAND PASS FILTER according to claim 1, wherein that the LC components of the tank circuits have a value selectively calculated by simulation or experimentally to adjust the resonance frequency of each tank circuit to the lower cut (f_pi) and the upper cut (f_ps) frequencies of the bandpass filter.

3. ANALOG BAND PASS FILTER according to claim 1, wherein that the control resistance R_c has a value selectively calculated by a method selected from simulation and experimentally, in order to increase or diminish the effect of the tank circuits on the filter response and to adjust the real response of the bandpass filter to the desired ideal response.