# US 2010/0167684 A1 · Quadrature signal generation in radio-frequency apparatus and associated methods > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2010/0167684 A1 - Document ID: US20100167684A1 - Status: Published application - Kind: A1 - Application number: 12/579,591 - Filed: 2009-10-15 - Published: 2010-07-01 - Earliest claimed: 2001-01-12 - Assignees: Silicon Laboratories Inc. - Inventors: Donald A. Kerth - Web page: https://patentgrep.com/patent/US20100167684A1 ## CPC - H04B 1/0003: {Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain (digital baseband systems H04L25/00; digital modulation/demodulation H04L27/00; CDMA H04B1/707; TDMA H04B7/2643; image transmission H04N5/00)} - H04B 1/28: the receiver comprising at least one semiconductor device having three or more electrodes - H04B 1/406: {with more than one transmission mode, e.g. analog and digital modes} - H04B 15/02: Reducing interference from electric apparatus by means located at or near the interfering apparatus - H04B 15/04: the interference being caused by substantially sinusoidal oscillations, e.g. in a receiver or in a tape-recorder - H04B 2215/064: Reduction of clock or synthesizer reference frequency harmonics - H04B: TRANSMISSION ## Abstract A radio-frequency (RF) apparatus, which may reside in a receiver or transceiver, includes receive-path circuitry. The receive-path circuitry includes a poly-phase filter and a harmonic filter. The poly-phase filter accepts an input signal and generates two output signals. One output signal of the poly-phase filter constitutes an in-phase (I) signal. The other output signal of the poly-phase filter constitutes a quadrature (Q) signal. The a harmonic filter couples to the poly-phase filter. The harmonic filter accepts as input signals the in-phase and quadrature output signals of the poly-phase filter. ## Claims ### Claim 1 A radio-frequency (RF) apparatus, comprising: receive-path circuitry, comprising: a poly-phase filter, the poly-phase filter configured to accept an input signal and provide a first in-phase signal and a first quadrature signal; and a harmonic filter coupled to the poly-phase filter, the harmonic filter configured to accept the first in-phase signal and the first quadrature signal. ### Claim 2 (depends on 1) The radio-frequency (RF) apparatus according to claim 1, wherein the harmonic filter is further configured to provide a second in-phase signal and a second quadrature signal. ### Claim 3 (depends on 2) The radio-frequency (RF) apparatus according to claim 2, wherein the harmonic filter is further configured to filter a third harmonic frequency of the input signal of the poly-phase filter. ### Claim 4 (depends on 3) The radio-frequency (RF) apparatus according to claim 3, wherein the harmonic filter comprises a passive filter. ### Claim 5 (depends on 3) The radio-frequency (RF) apparatus according to claim 3, wherein the harmonic filter comprises a passive complex filter. ### Claim 6 (depends on 3) The radio-frequency (RF) apparatus according to claim 3, wherein the harmonic filter comprises an active filter. ### Claim 7 (depends on 6) The radio-frequency (RF) apparatus according to claim 6, wherein the harmonic filter further comprises a transconductance circuitry coupled to a capacitor. ### Claim 8 (depends on 7) The radio-frequency (RF) apparatus according to claim 7, wherein the harmonic filter comprises complementary metal oxide semiconductor (CMOS) circuitry. ### Claim 9 (depends on 7) The radio-frequency (RF) apparatus according to claim 7, wherein the capacitor comprises an input capacitance of a limiter coupled to the harmonic filter. ### Claim 10 (depends on 3) The radio-frequency (RF) apparatus according to claim 3, further comprising a buffer coupled to the poly-phase filter, the buffer configured to accept a local oscillator signal, the buffer further configured to provide the input signal of the poly-phase filter. ### Claim 11 (depends on 10) The radio-frequency (RF) apparatus according to claim 10, further comprising: a first mixer coupled to the harmonic filter, the first mixer configured to mix a radio-frequency (RF) signal with the second in-phase signal; and a second mixer coupled to the harmonic filter, the second mixer configured to mix the ratio-frequency (RF) signal with the second quadrature signal. ### Claim 12 (depends on 10) The radio-frequency (RF) apparatus according to claim 10, further comprising: a first limiter coupled to the harmonic filter, the first limiter configured to accept the second in-phase signal, the first limiter further configured to generate a third in-phase signal; and a second limiter coupled to the harmonic filter, the second limiter configured to accept the second quadrature signal, the second limiter further configured to generate a third quadrature signal. ### Claim 13 (depends on 12) The radio-frequency (RF) apparatus according to claim 12, further comprising: a first mixer coupled to the first limiter, the first mixer configured to mix a radio-frequency (RF) signal with the third in-phase signal; and a second mixer coupled to the second limiter, the second mixer configured to mix the ratio-frequency (RF) signal with the third quadrature signal. ### Claim 14 (depends on 3) The radio-frequency (RF) apparatus according to claim 3, wherein the receive-path circuitry comprises low-intermediate-frequency (low-IF) circuitry. ### Claim 15 (depends on 3) The radio-frequency (RF) apparatus according to claim 3, wherein the receive-path circuitry comprises direct-conversion circuitry. ### Claim 16 A radio-frequency (RF) apparatus, comprising: receive-path circuitry, comprising: a harmonic filter, the harmonic filter configured to accept an input signal and to provide an output signal; and a poly-phase filter coupled to the harmonic filter, the poly-phase filter configured to accept the output signal of the harmonic filter. ### Claim 17 (depends on 16) The radio-frequency (RF) apparatus according to claim 16, wherein the poly-phase filter is further configured to provide a second in-phase signal and a second quadrature signal. ### Claim 18 (depends on 17) The radio-frequency (RF) apparatus according to claim 17, wherein the harmonic filter is further configured to filter a third harmonic frequency of the input signal. ### Claim 19 (depends on 18) The radio-frequency (RF) apparatus according to claim 18, wherein the harmonic filter comprises a passive filter. ### Claim 20 (depends on 18) The radio-frequency (RF) apparatus according to claim 18, wherein the harmonic filter comprises a passive complex filter. ### Claim 21 (depends on 18) The radio-frequency (RF) apparatus according to claim 18, wherein the harmonic filter comprises an active filter. ### Claim 22 (depends on 21) The radio-frequency (RF) apparatus according to claim 21, wherein the harmonic filter further comprises a transconductance circuitry coupled to a capacitor. ### Claim 23 (depends on 22) The radio-frequency (RF) apparatus according to claim 22, wherein the harmonic filter comprises complementary metal oxide semiconductor (CMOS) circuitry. ### Claim 24 A method of generating quadrature signals in a radio-frequency (RF) apparatus, the method comprising: filtering an input signal in a poly-phase filter; generating a first in-phase signal and a first quadrature signal; and filtering the first in-phase signal and the first quadrature signal in a harmonic filter. ### Claim 25 (depends on 24) The method according to claim 24, further comprising generating a second in-phase signal and a second quadrature signal with the harmonic filter. ### Claim 26 (depends on 25) The method according to claim 25, wherein filtering the first in-phase signal and the first quadrature signal in the harmonic filter further comprises filtering a third harmonic frequency of the output signal of the poly-phase filter. ### Claim 27 (depends on 26) The method according to claim 26, wherein the harmonic filter in filtering the first in-phase signal and the first quadrature signal comprises a passive filter. ### Claim 28 (depends on 26) The method according to claim 26, wherein the harmonic filter in filtering the first in-phase signal and the first quadrature signal comprises an active filter. ### Claim 29 (depends on 26) The method according to claim 26, wherein the harmonic filter comprises an active filter.