# US 2013/0154761 A1 · System and Method for a Radio Frequency Switch > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0154761 A1 - Document ID: US20130154761A1 - Status: Published application - Kind: A1 - Application number: 13/325,860 - Filed: 2011-12-14 - Published: 2013-06-20 - Earliest claimed: 2011-12-14 - Assignees: Infineon Technologies AG - Inventors: Nikolay Ilkov - Web page: https://patentgrep.com/patent/US20130154761A1 ## CPC - H04B 1/0057: {using diplexing or multiplexing filters for selecting the desired band} - H03H 7/465: {having variable circuit topology, e.g. including switches} - H04B 1/006: {using switches for selecting the desired band (H04B1/0057 takes precedence)} - H03K 17/693: Switching arrangements with several input- or output-terminals, e.g. multiplexers, distributors (logic circuits H03K19/00; code converters H03M5/00, H03M7/00) - H04B: TRANSMISSION - H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P) - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) ## Abstract In accordance with an embodiment, a filter network is configured to be coupled to a first switch, a second switch, and an output port. The filter network includes a first filter coupled between the first switch and the output port, and the second filter coupled between the second switch and the output port. The first filter has a pass band having a first frequency range that includes a first frequency, and a stop band that includes a second frequency that is a distortion product of the first frequency. The second filter has a second frequency range that includes the second frequency and the stop band that includes the first frequency. The second frequency range is higher in frequency than the first frequency range. ## Claims ### Claim 1 A filter network configured to be coupled to a first switch, a second switch and an output port, the filter network comprising: a first filter coupled between the first switch and the output port, the first filter having a pass band comprising a first frequency range that includes a first frequency, and a stop band comprising a second frequency, the second frequency being a distortion product of the first frequency; and a second filter coupled between the second switch and the output port, the second filter having a pass band comprising a second frequency range that includes the second frequency, and a stop band comprising the first frequency, wherein the second frequency range is higher in frequency than the first frequency range. ### Claim 2 (depends on 1) The filter network of claim 1, wherein: the first filter comprises a low pass filter having a pass band at the first frequency; and the second filter comprises a high pass filter having a pass band at the second frequency. ### Claim 3 (depends on 1) The filter network of claim 1, wherein: the first filter comprises a notch filter having a notch at the second frequency; and the second filter comprises a notch filter having a notch at the first frequency. ### Claim 4 (depends on 1) The filter network of claim 1, wherein: the first filter comprises a first parallel LC circuit; and the second filter comprises a second parallel LC circuit. ### Claim 5 (depends on 4) The filter network of claim 4, wherein the distortion product is a second harmonic of the first frequency. ### Claim 6 An antenna switch comprising: a first switching network configured to operate at a first frequency range, the first frequency range including a first frequency; a second switching network configured to operate at a second frequency range, the second frequency range being higher in frequency than the first frequency range; an output port configured to be coupled to an antenna; a first filter coupled between the first switching network and the output port, the first filter having a pass band comprising the first frequency range, and a stop band comprising a second frequency that is a harmonic of the first frequency; and a second filter coupled between the second switching network and the output port, the second filter having a pass band comprising the second frequency range and a stop band comprising the first frequency. ### Claim 7 (depends on 6) The antenna switch of claim 6, wherein the second filter attenuates an amplitude of the first frequency that is output by the first switching network, such that non-linearities within the second switching network generate less harmonics of the first frequency. ### Claim 8 (depends on 6) The antenna switch of claim 6, wherein: the first switching network comprises a plurality of first switches; and the second switching network comprises a plurality of second switches. ### Claim 9 (depends on 8) The antenna switch of claim 8, wherein each of the plurality of first switches and second switches comprise MOS transistors. ### Claim 10 (depends on 6) The antenna switch of claim 6, wherein: the first filter comprises a low pass filter; and the second filter comprises a high pass filter. ### Claim 11 (depends on 6) The antenna switch of claim 6, wherein: the first filter comprises a notch filter having a notch at the second frequency; and the second filter comprises a notch filter having a notch at the first frequency. ### Claim 12 (depends on 6) The antenna switch of claim 6, wherein: the first filter comprises a first parallel LC circuit; and the second filter comprises a second parallel LC circuit. ### Claim 13 (depends on 6) The antenna switch of claim 6, wherein the second frequency is a second harmonic of the first frequency. ### Claim 14 (depends on 6) The antenna switch of claim 6, wherein the first frequency is about 786 MHz; and the second frequency is about 1572 MHz. ### Claim 15 (depends on 6) The antenna switch of claim 6, further comprising a matching network coupled between the second switching network and the second filter. ### Claim 16 An RF transmission system comprising: a first transmitter configured to operate within a first frequency range, the first frequency range including a first frequency; a second transmitter configured to operate within a second frequency range, the second frequency range higher than the first frequency range; an output port; a first switch coupled between the first transmitter and the output port; a second switch coupled between the second transmitter and the output port; a first filter coupled between the first switch and the output port, the first filter having a pass band comprising the first frequency range, and a stop band comprising the second frequency, the second frequency being a harmonic of the first frequency; and a second filter coupled between the second switch and the output port, the second filter having a pass band comprising the second frequency range and a stop band comprising the first frequency. ### Claim 17 (depends on 16) The RF transmission system of claim 16, further comprising an antenna coupled to the output port. ### Claim 18 (depends on 16) The RF transmission system of claim 16, wherein: the first filter comprises a first notch filter having a notch at the second frequency; and the second filter comprises a second notch filter having a notch at the first frequency. ### Claim 19 (depends on 18) The RF transmission system of claim 18, wherein: the first filter comprises a first parallel LC circuit; and the second filter comprises a second parallel LC circuit. ### Claim 20 (depends on 16) The RF transmission system of claim 16, wherein: the first filter comprises a first single-tank parallel LC notch filter having a notch at the second frequency; and the second filter comprises a second single-tank parallel LC notch filter having a notch at the first frequency. ### Claim 21 (depends on 16) The RF transmission system of claim 16, wherein the second frequency is within a Global Positioning System (GPS) band. ### Claim 22 A method of operating an antenna switch comprising a first switching network configured to operate at a first frequency range, a second switching network configured to operate at a second frequency range, an output port configured to be coupled to an antenna, a first filter coupled between a first switching network and the output port, and a second filter coupled between the second switching network and the output port, the method comprising: coupling a RF transmitter to the output port via the first switching network, coupling comprising turning-on a switch within the first switching network; transmitting a signal at a first frequency with the RF transmitter, wherein the first frequency is within the first frequency range; attenuating a harmonic of the first frequency with the first filter; passing the first frequency though the first filter; and attenuating the first frequency with the second filter. ### Claim 23 (depends on 22) The method of claim 22, wherein the attenuating a harmonic of the first frequency with the first filter comprises attenuating the second harmonic of the first frequency.