# US 2014/0153616 A1 · Sliding if transceiver architecture > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0153616 A1 - Document ID: US20140153616A1 - Status: Published application - Kind: A1 - Application number: 13/691,238 - Filed: 2012-11-30 - Published: 2014-06-05 - Earliest claimed: 2012-11-30 - Assignees: QUALCOMM Incorporated - Applicants: Qualcomm Incorporated - Inventors: Faramarz Sabouri; Alberto Cicalini - Web page: https://patentgrep.com/patent/US20140153616A1 ## CPC - H04B 1/40: Circuits - H04B 1/403: using the same oscillator for generating both the transmitter frequency and the receiver local oscillator frequency - H04B: TRANSMISSION ## Abstract Techniques for providing a transceiver with a sliding intermediate frequency (IF). In an aspect, a PLL generates a single local oscillator (LO) signal used for both up-conversion by a transmit (TX) signal path and down-conversion by a receive (RX) signal path, wherein the LO frequency is chosen as the TX carrier frequency. As the TX and RX carrier frequencies may generally differ by a variable amount, the RX signal path utilizing the (TX) LO frequency for down-conversion may be characterized as having a “sliding” IF. To accommodate the sliding IF receiver architecture, specific processing functions such as charge sampling, discrete-time analog band-pass filtering, and sub-sampling analog-to-digital conversion (ADC) are described. ## Claims ### Claim 1 An apparatus comprising: a transmit signal path configured to upconvert a transmit signal using a transmit (TX) local oscillator (LO) having a TX LO frequency; and a receive signal path configured to downconvert a receive signal using a receive (RX) LO having the TX LO frequency, the receive signal path comprising a discrete-time analog filter configured to process the downconverted receive signal. ### Claim 2 (depends on 1) The apparatus of claim 1, the discrete-time analog filter comprising a discrete-time analog band-pass filter. ### Claim 3 (depends on 1) The apparatus of claim 1, further comprising a duplexer isolating the transmit signal path and from the receive signal path, the duplexer designed to operate with an RX-to-TX duplexer frequency separation, wherein a passband of the discrete-time analog filter includes the RX-to-TX duplexer frequency separation. ### Claim 4 (depends on 1) The apparatus of claim 1, further comprising a phase-locked loop configured to generate a single LO signal that is used for both the TX and RX local oscillators, wherein the single LO signal is further supplied to the discrete-time analog filter to control one or more switches for sampling an input to the discrete-time analog filter. ### Claim 5 (depends on 1) The apparatus of claim 1, further comprising a continuous-time band-pass filter coupled to the output of a mixer of the receive signal path. ### Claim 6 (depends on 1) The apparatus of claim 1, further comprising: a charge sampler configured to integrate a signal derived from the output of a mixer of the receive signal path for an integration duration, the charge sampler further configured to sample the output of the integration according to a charge sampler sampling interval. ### Claim 7 (depends on 6) The apparatus of claim 6, the charge sampler comprising: a trans-conductance amplifier configured to convert the signal derived from the output of the mixer to a current; and a sampling capacitor selectively coupleable to the output of the trans-conductance amplifier, wherein the sampling capacitor is coupled to the output of the transconductance amplifier for a portion of the charge sampler sampling interval, and the sampling capacitor is reset at the end of the portion of the charge sampler sampling interval. ### Claim 8 (depends on 5) The apparatus of claim 5, further comprising: a charge sampler configured to integrate a signal derived from the output of a mixer of the receive signal path for an integration duration, the charge sampler further configured to sample the output of the integration according to a charge sampler sampling interval, wherein the signal derived from the mixer is a voltage generated by the continuous-time band-pass filter. ### Claim 9 (depends on 5) The apparatus of claim 5, the discrete-time analog filter comprising: a discrete-time (DT) switched capacitor circuit; and a discrete-time switch selectively coupling a DT input voltage derived from the output of the continuous-time band-pass filter to the switched-capacitor circuit. ### Claim 10 (depends on 9) The apparatus of claim 9, the discrete-time switched capacitor circuit comprising: a plurality of capacitors, each capacitor selectively coupled to the discrete-time switch by a corresponding series-coupled capacitor-switch; wherein the series-coupled capacitor-switches are configured to successively sample the DT input voltage onto the plurality of capacitors, and to share the charge amongst the plurality of capacitors during a predetermined time interval to generate the output of the discrete-time switched capacitor circuit. ### Claim 11 (depends on 1) The apparatus of claim 1, further comprising: an analog-to-digital converter (ADC) for converting a signal of the receive signal path to a digital signal, the ADC configurable to sample a voltage using an ADC sampling clock derived from the RX LO. ### Claim 12 (depends on 11) The apparatus of claim 11, the receive signal having a carrier frequency, the difference between the carrier frequency and the LO frequency comprising an intermediate frequency. ### Claim 13 (depends on 1) The apparatus of claim 1, the receive signal path comprising an in-phase (I) mixer and a quadrature (Q) mixer, wherein the RX LO comprises an I local oscillator signal and a Q local oscillator signal. ### Claim 14 An apparatus comprising: means for mixing a transmit signal with a transmit (TX) local oscillator (LO) having a TX LO frequency; means for mixing a receive signal with a receive (RX) local oscillator (LO) having the TX LO frequency to generate a mixer output; and means for filtering in discrete time a signal derived from the mixer output. ### Claim 15 (depends on 14) The apparatus of claim 14, further comprising: means for filtering the mixer output in continuous time, the signal derived from the mixer output comprising the output of the means for filtering in continuous time. ### Claim 16 (depends on 14) The apparatus of claim 14, further comprising: means for integrating a second signal derived from the mixer output; and means for sampling the output of the means for integrating according to a charge sampler interval, the signal derived from the mixer output comprising the output of the means for sampling. ### Claim 17 (depends on 14) The apparatus of claim 14, further comprising: means for sub-sampling the output of the means for filtering in discrete time; and means for digitizing the output of the means for sub-sampling. ### Claim 18 A method comprising: mixing a transmit signal with a transmit (TX) local oscillator (LO) having a TX LO frequency; mixing a receive signal with a receive (RX) local oscillator (LO) having the TX LO frequency to generate a mixer output; and filtering a signal derived from the mixer output using a discrete-time analog band-pass filter. ### Claim 19 (depends on 18) The method of claim 18, further comprising filtering the mixer output using a continuous-time band-pass filter, the signal derived from the mixer output comprising the output of the continuous-time band-pass filter. ### Claim 20 (depends on 18) The method of claim 18, the filtering the signal comprising placing a notch of the discrete-time analog band-pass filter at a frequency corresponding to an interferer.