Filter circuit and radio terminal including filter circuit

A filter and circuit technology, which is applied in the field of radio terminals, can solve the problems of combining difficult bandpass filters with high-frequency integrated circuits, etc., and achieve the effects of expanding frequency range, steep attenuation characteristics, and increasing attenuation

CN102957391AInactive Publication Date: 2013-03-06SONY CORP
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2013-03-06
Estimated Expiration
Not applicable · inactive patent

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Abstract

The invention relates to a filter circuit and a radio terminal including the filter circuit. There is provided a filter circuit including a passive mixer circuit, and a passive switched capacitor circuit that is connected to a rear stage of the passive mixer and includes a flying capacitor. The passive mixer circuit generates a baseband signal by multiplying an input signal supplied from a predetermined signal source impedance by each local oscillation signal and outputs the baseband signal to the passive switched capacitor circuit, the passive switched capacitor circuit performs predetermined filtering on the baseband signal supplied from the passive mixer circuit and outputs the processed baseband signal, and a capacitance of the flying capacitor of the passive switched capacitor circuit is a capacitance by which input impedance of the passive mixer circuit is matched to the signal source impedance.
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Description

Technical field

[0001] The present invention relates to a filter circuit and a radio terminal including the filter circuit. Background technique

[0002] A mixer that converts the frequency of a high-frequency band signal and a band-pass filter that attenuates interference waves outside the high-frequency band are usually installed on a receiving front-end unit of a radio communication device. Since the band pass filter includes a surface acoustic wave filter and a dielectric resonator, it is difficult to incorporate the band pass filter into a high frequency integrated circuit. However, in recent years, attempts to integrate a frequency conversion filter circuit combining the two functions of a mixer and a bandpass filter into the front-end unit of the receiver have been reported, as shown in the following documents: BWCook , "Low-Power 2.4-GHz Transceiver With Passive RX Font-End and 400-mV Supply" by A. Berny, A. Molnar, S. Lanzisera and KSJPister, Journal of Solid State Circ...

Examples

no. 1 example

[0033] 3. The second embodiment of the present disclosure

[0034] 4. The third embodiment of the present disclosure

[0035] 5. Summary

[0036] 1. Related Technology

[0037] figure 1 It is a diagram illustrating a configuration example of a frequency conversion filter circuit according to the related art. figure 1 The frequency conversion filter circuit 10 shown in is rewritten in differential form in the following document Image 6 The circuit obtained by the quadrature mixer model disclosed in the document is BWCook, A. Berny, A. Molnar, S. Lanzisera and KSJPister’s "Low-Power 2.4-GHz Transceiver With Passive RX Font-End and 400-mV Supply", Journal of Solid State Circuits, Vol. 41, No. 12, pp. 2757-2766, Dec. 2006. In addition, "Low-Power 2.4-GHz Transceiver With Passive RX Font-End and 400-mV Supply" by BWCook, A. Berny, A. Molnar, S. Lanzisera and KSJPister, Journal of Solid State Circuits, Vol. 41, No. 12, pp. 2757-2766, in Dec. 2006 Image 6 The switch resistor Rsw of the p...