Programmable baseband filter for selecting between single pole or complex pole frequency response

Abstract

One aspect includes a filtering method comprising: operating a first filter to filter a first input signal to generate a first output signal; operating a second filter to filter a second input signal to generate a second output signal; and combining at least a portion of the second filter with the first filter to filter a third input signal to generate a third output signal. Another aspect includes a filtering method comprising: operating a switching device to configure a filter to have a first set(multiple) poles; using the filter configured with the first set(multiple) poles to filter a first input signal to generate a first output signal; operating a switching device to configure a filter to have a second set(multiple) poles; and using the filter configured with the second set(multiple) poles to filter a second input signal to generate a second output signal.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority and benefit to non-provisional patent application No. 17 / 318968 filed with the U.S. Patent and Trademark Office on May 12, 2021, and provisional patent application No. 63 / 045813 filed with the U.S. Patent and Trademark Office on June 29, 2020, the contents of which are incorporated herein as if their entire contents were fully set forth herein and used for all applicable purposes. Technical Field

[0003] This disclosure relates generally to baseband filters, and more specifically to baseband filters programmable for filter coupling, pole selection, noise reduction, and multi-pole configurations for improved stopband rejection. Background Technology

[0004] Wireless communication devices typically include a receiver with a low-noise amplifier (LNA), mixer, local oscillator (LO), baseband filter, and other processing circuitry to further process the received signal. The receiver can be configured to receive signals within different frequency channels. The operation of such devices within the receiver can depend on the specific channel being received. Therefore, the device should be configured to adapt to different channels in a way that does not overly complicate the integrated circuits (ICs) on which these devices are formed. Summary of the Invention

[0005] The following is a simplified overview of one or more embodiments to provide a basic understanding of such embodiments. This overview is not a comprehensive summary of all contemplated embodiments and is neither intended to identify key or essential elements of all embodiments nor to depict the scope of any or all embodiments. Its sole purpose is to present some concepts of one or more embodiments in a simplified form as a prelude to the more detailed description that follows.

[0006] One aspect of this disclosure relates to an apparatus. The apparatus includes a first filter; a second filter; and a first group of one or more switching devices configured to selectively couple the first filter to the second filter.

[0007] Another aspect of this disclosure relates to a method for filtering a signal. The method includes: operating a first filter to filter a first input signal to generate a first output signal; operating a second filter to filter a second input signal to generate a second output signal; and selectively coupling at least a portion of the second filter to the first filter to filter a third input signal to generate a third output signal.

[0008] Another aspect of this disclosure relates to a filter. The filter includes: a first amplifier; a first resistor and a second resistor, coupled in series between a first input of the filter and a first input of the first amplifier; a first feedback capacitor, coupled between a first output of the first amplifier and a first input; a capacitor, coupled to a first node between the first resistor and the second resistor; a first feedback resistor, coupled to a first output of the first amplifier; and a first switching device for selectively coupling the first feedback resistor to either the capacitor or the first input of the first amplifier.

[0009] Another aspect of this disclosure relates to a method for filtering a signal. The method includes: operating a set of one or more switching devices to configure a filter to have a first set of one or more poles; filtering a first input signal using the filter configured with the first set of one or more poles to generate a first output signal; operating a set of one or more switching devices to configure a filter to have a second set of one or more poles; and filtering a second input signal using the filter configured with the second set of one or more poles to generate a second output signal.

[0010] Another aspect of this disclosure relates to a filter. The filter includes: a first amplifier having a differential input and a differential output; a first feedback resistor and a second feedback resistor, respectively coupled between the differential input and the differential output; and a plurality of switching devices configured to selectively couple the first feedback resistor to the second feedback resistor.

[0011] To achieve the foregoing and related objectives, one or more embodiments include the features fully described below and particularly pointed out in the claims. The following description and accompanying drawings illustrate certain illustrative aspects of one or more embodiments in detail. However, these aspects indicate only some of the various ways in which the principles of various embodiments may be employed, and the description of the embodiments is intended to include all such aspects and their equivalents. Attached Figure Description

[0012] Figure 1A A schematic diagram / block diagram of an example receiver according to one aspect of this disclosure is shown.

[0013] Figure 1B The illustration shows a graph of the spectrum and frequency response of an example received channel and baseband filter according to another aspect of this disclosure.

[0014] Figure 1C The illustration shows a graph of the spectrum and frequency response of a channel and baseband filter received according to another example of another aspect of this disclosure.

[0015] Figure 1DThe illustration shows a graph of the spectrum and frequency response of a channel and baseband filter received according to another example of another aspect of this disclosure.

[0016] Figure 2A A schematic diagram of an example programmable baseband filter according to another aspect of this disclosure is illustrated.

[0017] Figure 2B The illustration shows a first configuration according to another aspect of this disclosure. Figure 2A A schematic diagram of an example programmable baseband filter.

[0018] Figure 2C The illustration shows a second configuration according to another aspect of this disclosure. Figure 2A A schematic diagram of an example programmable baseband filter.

[0019] Figure 2D The illustration shows a third configuration according to another aspect of this disclosure. Figure 2A A schematic diagram of an example programmable baseband filter.

[0020] Figure 2E The illustration shows a fourth configuration according to another aspect of this disclosure. Figure 2A A schematic diagram of an example programmable baseband filter.

[0021] Figure 2F The illustration shows a fifth configuration according to another aspect of this disclosure. Figure 2A A schematic diagram of an example programmable baseband filter.

[0022] Figure 2G The illustration shows a sixth configuration according to another aspect of this disclosure. Figure 2A A schematic diagram of an example programmable baseband filter.

[0023] Figure 3A The illustration shows a spectrum and frequency response of an example channel and a single-pole baseband filter in zero intermediate frequency (ZIF) reception mode according to another aspect of this disclosure.

[0024] Figure 3B The illustration shows a graph of the spectrum and frequency response of a channel and a single-pole baseband filter in an off-zero intermediate frequency (OZIF) receiver mode according to another aspect of this disclosure.

[0025] Figure 3C The illustration shows the spectrum and frequency response of another example received channel and complex pole baseband filter in Offset Zero Intermediate Frequency (OZIF) receiver mode according to another aspect of this disclosure.

[0026] Figure 4AThe illustration shows a schematic diagram of another example programmable baseband filter in a first configuration according to another aspect of the present disclosure.

[0027] Figure 4B The illustration shows a second configuration according to another aspect of this disclosure. Figure 4A A schematic diagram of an example programmable baseband filter.

[0028] Figure 5 A flowchart illustrating an example method for filtering a signal according to another aspect of this disclosure is shown.

[0029] Figure 6 The diagram illustrates a flowchart of another example method for filtering a signal according to another aspect of this disclosure.

[0030] Figure 7 A block diagram of an example wireless communication device according to another aspect of this disclosure is illustrated.

[0031] Figure 8 A schematic diagram / block diagram of another example receiver according to another aspect of this disclosure is shown.

[0032] Figure 9 A schematic diagram of another example of a programmable baseband filter according to another aspect of this disclosure is illustrated. Detailed Implementation

[0033] The detailed description that follows, taken in conjunction with the accompanying drawings, is intended as a description of various configurations and not as representing the only configuration in which the concepts described herein can be practiced. The detailed description includes specific details intended to provide a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts can be practiced without these specific details. In some cases, well-known structures and components are shown in block diagram form to avoid obscuring such concepts.

[0034] Figure 1A A schematic / block diagram of an example receiver 100 according to one aspect of this disclosure is illustrated. In this example, receiver 100 is configured to process a set of received channels, such as channel 1 having a corresponding component identified by a "-1" suffix, and channel 2 having a corresponding component identified by a "-2" suffix.

[0035] Regarding channel 1, receiver 100 includes antenna 110-1, low noise amplifier (LNA) 120-1 (which may include antenna impedance matching elements, such as those represented by a series circuit of an inductor and a capacitor coupled to ground), analog processing circuitry 130-1, I-mixer 140-1I, Q-mixer 140-1Q, local oscillator (LO) 150-1, I-baseband filter (I-BBF) 160-1I, and Q-BBF 160-1Q.

[0036] Antenna 110-1 receives, for example, wireless signals transmitted by a remote wireless communication device and outputs the received signal. LNA 120-1 amplifies the received signal. Analog processing circuitry 130-1 can perform one or more analog processing operations on the received signal, including but not limited to filtering, spatial processing, converting the signal to a differential signal, and / or others. As mentioned, the output of analog processing circuitry 130-1 can be differential and coupled to the differential inputs of I-mixer 140-1I and Q-mixer 140-1Q, respectively.

[0037] LO 150-1 provides the LO signal and the 90° phase-shifted LO signal to I-mixer 140-1I and Q-mixer 140-1Q, respectively. Correspondingly, I-mixer 140-1I and Q-mixer 140-1Q down-convert the I-component and Q-quadrature component of the received signal, respectively, to generate the I-input differential signal V. iI1+ / V iI1- and Q-input differential signal V iQ1+ / V iQ1- This is for use with I-BBF 160-1I and Q-BBF 160-1Q. I-BBF 160-1I and Q-BBF 160-1Q are used with input differential signal V. iI1+ / V iI1- and V iQ1+ / V iQ1- Filtering is performed to remove high-frequency conversion components and other unwanted signals such as interference signals from the signal, in order to generate the output differential signal V. oI1+ / V oI1- and V oQ1+ / V oQ1- Although not shown, the output differential signal V oI1+ / V oI1- and V oQ1+ / V oQ1- It is sent downstream for further processing, such as analog-to-digital conversion (ADC), demodulation, error correction, and decoding.

[0038] Similarly, regarding channel 2, receiver 100 includes antenna 110-2, low-noise amplifier (LNA) 120-2 (which may include antenna impedance matching elements, such as those represented by a series circuit of an inductor and a capacitor coupled to ground), analog processing circuitry 130-2, I-mixer 140-2I, Q-mixer 140-2Q, local oscillator (LO) 150-2, I-baseband filter (I-BBF) 160-2I, and Q-BBF 160-2Q.

[0039] Antenna 110-2 receives, for example, wireless signals transmitted by a remote wireless communication device and outputs the received signal. LNA 120-2 amplifies the received signal. Analog processing circuitry 130-2 can perform one or more analog processing operations on the received signal, including but not limited to filtering, spatial processing, converting the signal to a differential signal, and / or others. As mentioned, the output of analog processing circuitry 130-2 can be differential and coupled to the differential inputs of I-mixer 140-2I and Q-mixer 140-2Q, respectively.

[0040] LO 150-2 provides the LO signal and the 90° phase-shifted LO signal to I-mixer 140-2I and Q-mixer 140-2Q, respectively. Correspondingly, I-mixer 140-2I and Q-mixer 140-2Q down-convert the I-component and Q-quadrature component of the received signal, respectively, to generate the I-input differential signal V. iI2+ / V iI2- and Q-input differential signal V iQ2+ / V iQ2- This is for use with I-BBF160-2I and Q-BBF160-2Q. I-BBF160-2I and Q-BBF160-2Q are used with input differential signal V. iI2+ / V iI2- and V iQ2+ / V iQ2- Filtering is performed to remove high-frequency conversion components and other unwanted signals such as interference signals from the signal, in order to generate the output differential signal V. oI2+ / V oI2- and V oQ2+ / V oQ2- Although not shown, the output differential signal V oI2+ / V oI2- and V oQ2+ / V oQ2- It is sent downstream for further processing, such as analog-to-digital conversion (ADC), demodulation, error correction, and decoding.

[0041] The first and second channels can be independent for receiving two independent signals. Alternatively, the first and second channels can be used for spatial processing, such as multiple-input multiple-output (MIMO) processing. In the latter case, channel 1 can be used as the primary channel, and channel 2 can be used as the MIMO channel, and vice versa. Although two channels are shown for illustrative purposes, it should be understood that receiver 100 may include hardware for processing more than two channels, such as four channels (e.g., for 4x4 MIMO), five channels (e.g., for 100MHz carrier aggregation), eight channels (e.g., for dual subscriber information module (SIM) card operation), or ten channels (e.g., for 200MHz carrier aggregation). Furthermore, although the elements for processing two channels are illustrated in FIG. 1 as coupled to corresponding antennas 110-1 and 110-2, in some embodiments, LNA 120-1 and LNA 120-2 are both coupled to the same antenna. In some such embodiments, duplexer or filter elements may be coupled between one or more LNAs in LNA 110 and the antenna.

[0042] Due to the trend toward higher data throughput in such receivers 100, such as in the case of fifth-generation (5G) new radio (NR) for mobile networks developed by the 3rd Generation Partnership Project (3GPP) (referred to herein as "5G NR"), multiple channels for carrier aggregation (CA) can exist to achieve higher data throughput. For example, 10 channels (each with a bandwidth of 20 MHz) can provide a combined 200 MHz bandwidth for high data throughput applications.

[0043] To provide such multi-channel capability for high data throughput applications while maintaining a relatively small integrated circuit (IC) footprint (e.g., for cost-effective implementation of such a receiver), new technology nodes (such as 14-nanometer (nm) FinFETs) can be used in the active components, such as the I-BBF and Q-BBF 160-1I / 160-1Q and 160-2I / 160-2Q for channels 1 and 2 of receiver 100, respectively. Furthermore, for versatility, receiver 100 can be selectively reconfigured to handle channels specified by other standards, such as 4th generation broadband cellular networks (also known as Long Term Evolution (LTE)) and Global System for Mobile Communications (GSM) cellular networks developed by 3GPP.

[0044] The use of new technology nodes, for example in the active components of receiver 100, works well in filters with higher bandwidths (e.g., 5MHz to 160MHz bandwidth) for 5G NR. However, since LTE and GSM utilize narrower bandwidths (e.g., down to 600kHz to 1MHz), new technology nodes may introduce flicker noise, where filter stopband (out-of-band) suppression is poor for certain levels of flicker noise. This may be the case at low frequencies, as the level of flicker noise varies inversely with frequency (1 / f). To reduce flicker noise, new technology nodes could be made larger. However, making the device larger introduces additional parasitic capacitance, which can degrade the performance of applications utilizing wider bandwidths, such as in the case of 5G NR, where communication bands and / or channels can be wider and / or a large amount of carrier aggregation can be used. Furthermore, larger devices occupy more IC footprint, which can lead to higher product costs.

[0045] As discussed, for a general-purpose receiver, the bandwidth can be selectively reconfigured for 5G NR, 4G, and / or GSM cellular networks, and the I-BBF and Q-BBF 160-1I / 160-1Q and 160-2I / 160-2Q can be selectively reconfigured for different bandwidths. For example, for 5G NR, the I-BBF and Q-BBF 160-1I / 160-1Q and 160-2I / 160-2Q can be configured with poles in the range of approximately 100MHz. For 4G, the I-BBF and Q-BBF 160-1I / 160-1Q and 160-2I / 160-2Q can be configured with poles in the range of approximately 20MHz. Furthermore, for GSM, I-BBF and Q-BBF 160-1I / 160-1Q and 160-2I / 160-2Q can be configured with poles in the range of approximately 660kHz. Refer to the following diagram for a more detailed explanation.

[0046] Figure 1BThe diagram illustrates the spectrum (shaded area) and frequency response H(f) (dashed line) of an example received 5G NR channel (CHN) and baseband filter (BBF) according to another aspect of this disclosure. The spectrum and frequency response H(f) of the 5G NR channel CHN and BBF can be related to the case where receiver 100 is configured to process signals according to 5G NR. The diagram includes an x-axis or horizontal axis representing frequency (f) and a y-axis or vertical axis representing the power level of the received 5G NR CHN signal and the frequency response H(f) of the corresponding BBF. In this example, the spectrum of the received channel of interest, 5G NR CHN, has a bandwidth of approximately 100 MHz. Therefore, in order to filter the received 5G NR CHN signal to substantially eliminate unwanted signals (stopband rejection) to provide an acceptable signal-to-noise ratio (SNR), the frequency response H(f) of the BBF should have poles f at approximately -50 MHz and +50 MHz, respectively. p The passband of the filter's frequency response H(f) can be a pole f. p The region between the two points is essentially flat, and the roll-off of the filter frequency response H(f) can be at the poles f respectively. p The sloping sections below and above.

[0047] Figure 1C The diagram illustrates the spectrum (shaded area) and frequency response H(f) (dashed line) of an example received 4G channel (CHN) and baseband filter (BBF) according to another aspect of this disclosure. The spectrum and frequency response H(f) of the 4G CHN and BBF can be related to the case where the receiver 100 is configured to process signals according to 4G. In this example, the spectrum of the received channel of interest, 4G CHN, has a bandwidth of approximately 20 MHz. Therefore, in order to filter the signal of the received channel to substantially eliminate unwanted signals (stopband rejection) to provide an acceptable SNR, the frequency response H(f) of the BBF should have poles f at approximately -10 MHz and +10 MHz, respectively. p Similarly, the passband of the filter's frequency response H(f) can be at the pole f. p The region between them is basically flat, and the roll-off of the filter frequency response H(f) can be at the poles f respectively. p The sloping sections below and above.

[0048] Figure 1DThe diagram illustrates the spectrum (shaded area) and frequency response H(f) (dashed line) of an example received GSM channel (CHN) and baseband filter (BBF) according to another aspect of this disclosure. The spectrum and frequency response H(f) of the GSM CHN and BBF can be related to the case where the receiver 100 is configured to process signals according to GSM. In this example, the spectrum of the received channel of interest, GSM CHN, has a bandwidth of approximately 600 kHz. Therefore, in order to filter the signal of the received channel to substantially eliminate unwanted signals and provide an acceptable SNR, the frequency response H(f) of the BBF should have poles f at approximately -300 kHz and +300 kHz, respectively. p Similarly, the passband of the filter's frequency response H(f) can be at the pole f. p The region between the two points is essentially flat, and the roll-off of the filter frequency response H(f) can be at the poles f respectively. p The sloping sections below and above.

[0049] Filters can include resistors and capacitor banks to frequency-shift poles when handling different applications, such as 5G NR, 4G, and GSM applications. However, resistor and capacitor banks are typically large and occupy a significant amount of IC space; and therefore, they may not be very cost-effective. Furthermore, switching on and off groups of resistors and capacitors can introduce increased parasitic capacitance, which can adversely affect filter performance, such as frequency selectivity and noise suppression.

[0050] Figure 2A A schematic diagram of an example programmable baseband filter 200 according to another aspect of this disclosure is illustrated. In general, the baseband filter 200 includes a pair of baseband filters (BBFs) 210 and 250, which can be selectively coupled together in different ways to achieve improved performance for the filter 200 in different bandwidths for a particular application (e.g., specific bandwidths used in 5G NR, 4G, and GSM cellular networks).

[0051] In some bandwidth-specific applications, pairs of BBF 210 and BBF 250 can be selectively coupled to each other to process a single received signal (e.g., a single channel). However, in other applications, pairs of BBF 210 and BBF 250 can also be completely decoupled to process separate received signals (e.g., two different channels) independently. Different ways of selectively coupling pairs of BBF 210 and BBF 250 are possible.

[0052] For example, in applications requiring relatively narrow bandwidth and low noise, the first BBF 210 can borrow active and passive components from the second BBF 250, where borrowing active components reduces flicker noise due to the increased (e.g., doubled) effective device size, and borrowing passive components (e.g., resistors and capacitors) results in narrower (or tighter) poles and / or increased stopband rejection (e.g., at lower frequencies). In this case, the second BBF 250 is not used to filter signals separated from those filtered by the first BBF 210 using the borrowed components of the second BBF 250. For ultra-narrow bandwidth applications, the first BBF 210 can also be selectively coupled to a capacitor bank to further narrow the pole frequency for improved stopband rejection at such low frequencies (e.g., in the case of GSM).

[0053] In applications with relatively narrow bandwidth and low power, the first BBF 210 can borrow passive components (not active components) from the second BBF 250. This borrowing of passive components (resistors and capacitors) results in narrower (tighter) poles and / or increased stopband rejection (e.g., at lower frequencies), while simultaneously disabling the active components of the second BBF 250 to save power. Similarly, in this case, the second BBF 250 is not used to filter signals separated from those filtered by the first BBF 210 using the borrowed components of the second BBF 250.

[0054] In applications requiring relatively wide bandwidth and low noise, the first BBF 210 can borrow active components (not passive components) from the second BBF 250, where the borrowing of active components reduces flicker noise due to the increase in effective device size (e.g., doubling), and the narrower (tighter) poles do not require passive components. Similarly, in this case, the second BBF 250 is not used to filter the signal separated from the signal filtered by the first BBF 210 using the borrowed components of the second BBF 250.

[0055] As an example, the first BBF 210 can be selectively coupled to the second BBF 250 to borrow an amplifier from the second BBF 250, regardless of whether the associated (resistor-capacitor (RC)) feedback network is borrowed. Similarly, the first BBF 210 can be selectively coupled to the second BBF 250 to borrow a feedback network from the BBF 250, regardless of whether the feedback network is borrowed from its associated amplifier. In some embodiments, the amplifier from the BBF 250 and its associated feedback network may be independently and selectively coupled to the first BBF 210. In this embodiment, the first BBF 210, more specifically, one or more switching devices in a group, may be configured to borrow an amplifier from the second BBF 250 but not its associated feedback network. Alternatively, the first BBF 210, more specifically, one or more switching devices in a group, may be configured to borrow a feedback network from the second BBF 250 but not its associated amplifier. As a further alternative, the first BBF 210, more specifically, a group of one or more switching devices, can be configured to borrow an amplifier and its associated resistor-capacitor (RC) feedback network from the second BBF 250.

[0056] Referring to receiver 100, the first BBF 210 can be either I-BBF 160-1I or Q-BBF 160-1Q for channel 1. The second BBF 250 can be either I-BBF 160-2I or Q-BBF 160-2Q for channel 2. For example, the I-BBFs of channel 1 and channel 2 can be selectively coupled together, and / or the Q-BBFs of channel 1 and channel 2 can be selectively coupled together. If BBF 210 and BBF 250 are used to process discrete signals, such as in two different channels or in the case of a main channel and a MIMO channel, then BBF 210 and BBF 250 are completely decoupled from each other. Therefore, there can be no IC area penalty, as the second BBF 250 might be needed to perform discrete channel processing. However, if the second BBF 250 is not used for separate channel processing, the first BBF 210 can be selectively coupled to the second BBF 250 to borrow active or passive components or both, in order to modify its filtering performance, for example, based on different bandwidth applications.

[0057] More specifically, the first BBF 210 includes components configured to receive the differential signal V. i1+ / V i1- The differential input can be generated by one of mixers 140-1I and 140-1Q of receiver 100. The first BBF 210 also includes a capacitor C coupled across the differential input. 11Another capacitor C is coupled between the positive side of the differential input and ground. 12+ And another capacitor C coupled between the negative side of the differential input and ground. 12- The first BBF 210 also includes a first resistor group 212+ coupled between the positive side of the differential input and the positive input of the first-stage amplifier 220. Furthermore, the first BBF 210 includes a second resistor group 212- coupled between the negative side of the differential input and the negative input of the amplifier 220. The amplifier 220 can be configured as a transimpedance amplifier (TIA), such as... Figures 2A-2G As indicated, and may include two or more internal amplification stages. For example, a first internal amplification stage of amplifier 220 may have an input coupled (directly coupled or coupled through one or more components such as another internal amplification stage) to resistor group 212, and may have an output coupled to the input of a second internal amplification stage of amplifier 220; the second internal amplification stage of amplifier 220 may have an output coupled (directly coupled or coupled through one or more components such as another internal amplification stage) to resistor R. 14 The output of (described below).

[0058] The first BBF 210 also includes a first resistor-capacitor (RC) feedback network, which includes a resistor R 13+ A capacitor C (which can be variable) is connected in parallel between the negative output and positive input of the TIA 220. 13+ (This can be variable). Similarly, the first BBF210 also includes a second RC feedback network, which includes resistor R. 13- A capacitor C (which can be variable) is connected in parallel between the positive output and negative input of the TIA 220. 13- (Can be variable). Includes RC feedback network C 13+ / R 13+ and C 13- / R 13- The TIA 220, the first and second resistor groups 212+ and 212-, and the capacitor C 11 C 12+ and C 12- This forms the first filter stage of the first BBF 210. It can be configured with resistors 212+ and 212-, and feedback capacitor C. 13+ / C 13- The capacitor and feedback resistor R 13+ / R 13- The resistance is variable to set the poles of the first filter stage.

[0059] The first BBF 210 also includes a resistor R series coupled between the negative output of the TIA 220 and the positive input of the second-stage amplifier 230.14+ and R 15+ (One or both of these may be variable.) The first BBF 210 also includes a resistor R series coupled between the positive output of TIA 220 and the negative input of amplifier 230. 14- and R 15- (One or both of these can be variable). Amplifier 230 can be configured as a programmable gain amplifier (PGA), such as... Figures 2A-2G As indicated herein, and may include two or more internal amplification stages. For example, the first internal amplification stage of amplifier 230 may have coupling (direct coupling or coupling via one or more components such as another internal amplification stage) to resistor R. 15 The input of the amplifier 230 may have an output coupled to the input of a second internal amplification stage of the amplifier 230; the second internal amplification stage of the amplifier 230 may have an output coupled (directly coupled or coupled through one or more components such as another internal amplification stage) to the output of a filter (described below).

[0060] Although not in Figures 2A-2G As shown, but the capacitor can be coupled to the resistor R. 14+ and R 15+ The first node between resistor R 14- and R 15- Between the second node, additional poles are provided for the second filter stage, as discussed further in this paper with reference to another filter implementation. Alternatively, a single resistor (which may be variable) can be used instead of R. 14+ and R 15+ And / or a single resistor (which can be variable) can be used instead of R. 14- and R 15- .

[0061] The first BBF 210 also includes a third RC feedback network, which includes resistor R 16+ A capacitor C (which can be variable) is connected in parallel between the negative output and positive input of the PGA 230. 16+ (This can be variable). Similarly, the first BBF 210 also includes a fourth RC feedback network, which includes resistor R. 16- A capacitor C (which can be variable) is connected in parallel between the positive output and negative input of the PGA 230. 16- (It can be variable).

[0062] The PGA 230 includes differential outputs to generate a filtered differential output signal V. o1+ / V o1-The output differential signal V of receiver 100, such as the I-BBF 160-1I or Q-BBF 160-1Q. oI1+ / V oI1- or V oQ1+ / V oQ1- Including RC feedback network C 16+ / R 16+ and C 16- / R 16- PGA 230 and resistor R 14+ / R 15+ and R 14- / R 15- This forms the second filter stage of the first BBF 210. Resistor R can be used to... 14+ / R 15+ and R 14- / R 15- The resistor and the feedback capacitor C 13+ / C 13- The capacitor and feedback resistor R 13+ / R 13- The resistance is variable to set the poles (multiple) of the second filter stage.

[0063] The second BBF 250 can be configured to be the same as or similar to the first BBF 210. Specifically, the second BBF 250 includes components configured to receive the differential signal V. i2+ / V i2- The differential input can be generated by one of the mixers 140-2I and 140-2Q of receiver 100. The second BBF 250 also includes a capacitor C coupled across the differential input. 21 Another capacitor C is coupled between the positive side of the differential input and ground. 22+ And another capacitor C coupled between the negative side of the differential input and ground. 22- The second BBF 250 also includes a first resistor group 252+ coupled between the positive side of the differential input and the positive input of the first-stage amplifier 260. Furthermore, the second BBF 250 includes a second resistor group 252- coupled between the negative side of the differential input and the negative input of the amplifier 260. The amplifier 260 can be configured as a transimpedance amplifier (TIA), such as... Figures 2A-2GAs indicated, and may include two or more internal amplification stages. For example, a first internal amplification stage of amplifier 260 may have an input coupled (directly coupled or coupled through one or more components such as another internal amplification stage) to resistor group 252, and may have an output coupled to the input of a second internal amplification stage of amplifier 260; the second internal amplification stage of amplifier 260 may have a coupling (directly coupled or coupled through one or more components such as another internal amplification stage) to resistor R. 24 The output of (described below).

[0064] TIA 260 may also include an enable input for receiving a first enable signal (en1) for selectively enabling and disabling TIA 260 (e.g., by turning on / off at least one headswitch coupled to a DC (Vdd) power supply rail). Although not shown, TIA 220 may also include a similar enable input.

[0065] The second BBF 250 also includes a first RC feedback network, which includes a resistor R 23+ A capacitor C (which can be variable) is connected in parallel between the negative output and positive input of the TIA 260. 23+ (This can be variable). Similarly, the second BBF 250 also includes a second RC feedback network, which includes resistor R. 23- A capacitor C (which can be variable) is connected in parallel between the positive output and negative input of the TIA 260. 23- (Can be variable). Includes RC feedback network C 23+ / R 23+ and C 23- / R 23- The TIA 260, the first and second resistor groups 252+ and 252-, and the capacitor C 21 C 22+ and C 22- This forms the first filter stage of the second BBF 250. It can be configured with resistors in resistor banks 252+ and 252-, and feedback capacitor C. 23+ / C 23- The capacitor and feedback resistor R 23+ / R 23- The resistance is variable to set the poles of the first filter stage.

[0066] The second BBF 250 also includes a resistor R series coupled between the negative output of the TIA 260 and the positive input of the second-stage amplifier 270. 24+ and R 25+(One or both of these may be variable). The second BBF 250 also includes a resistor R series coupled between the positive output of the TIA 260 and the negative input of the amplifier 270. 24- and R 25- (One or both of these can be variable). Amplifier 270 can be configured as a programmable gain amplifier (PGA), such as... Figures 2A-2G As indicated herein, and may include two or more internal amplification stages. For example, the first internal amplification stage of amplifier 270 may have coupling (direct coupling or coupling via one or more components such as another internal amplification stage) to resistor R. 25 The input of the amplifier 270 may have an output coupled to the input of a second internal amplification stage of the amplifier 270; the second internal amplification stage of the amplifier 270 may have an output coupled (directly coupled or coupled through one or more components such as another internal amplification stage) to the output of a filter (described below).

[0067] Although not shown in Figure 2, a capacitor can be coupled to resistor R. 24+ and R 25+ The first node between resistor R 24- and R 25- Between the second node, additional poles are provided for the second filter stage, as discussed with reference to another filter implementation. Alternatively, a single resistor (which may be variable) can be used instead of R. 24+ and R 25+ And / or a single resistor (which can be variable) can be used instead of R. 24- and R 25- .

[0068] PGA 270 may also include an enable input for receiving a second enable signal (en2) for selectively enabling and disabling PGA 270 (e.g., by turning on / off at least one head switch coupled to the DC power supply (Vdd) rail). Although not shown, PGA 230 may also include a similar enable input.

[0069] The second BBF 250 also includes a third RC feedback network, which includes resistor R 26+ A capacitor C (which can be variable) is coupled in parallel between the negative output and positive input of the PGA 270. 26+ (This can be variable). Similarly, the second BBF 250 also includes a fourth RC feedback network, which includes resistor R. 26- A capacitor C (which can be variable) is connected in parallel between the positive output and negative input of the PGA 270. 26- (It can be variable).

[0070] The PGA 270 includes differential outputs to generate a filtered differential output signal V. o2+ / V o2- The output differential signal V of receiver 100, such as the I-BBF 160-2I or Q-BBF 160-2Q. oI2+ / V oI2- or V oQ2+ / V oQ2- (In the case where the BBF 210 and BBF250 are not coupled together via a set of switching devices, as discussed further herein). This includes the RC feedback network C. 26+ / R 26+ and C 26- / R 26- PGA 270 and resistor R 24+ / R 25+ and R 24- / R 25- This forms the second filter stage of the second BBF 250. Resistor R can be used to... 24+ / R 25+ and R 24- / R 25- The resistor and the feedback capacitor C 26+ / C 26- The capacitor and feedback resistor R 26+ / R 26- The resistance is variable to set the poles (multiple) of the second filter stage.

[0071] The programmable BBF 200 also includes a set of switching devices for selectively coupling the individual nodes of BBF 210 and BBF 250 together to configure one of the filters (such as the first BBF 210) to have certain characteristics while disabling other filters (such as the second BBF 250) from filtering independent signals.

[0072] For example, BBF 200 includes switchgear SW. 1+ and SW 1- This is used to selectively couple the positive and negative sides of the differential inputs of the first BBF 210 and the second BBF 250 together, respectively. BBF 200 also includes a switching device SW. 3+ and SW 3- This is used to selectively couple the positive and negative inputs of TIA 220 of the first BBF 210 and TIA 260 of the second BBF 250 together, respectively. The BBF 200 also includes a switching device SW. 7+ and SW 7-This is used to selectively couple the negative and positive outputs of TIA 220 of the first BBF 210 and TIA 260 of the second BBF 250 together, respectively. Furthermore, BBF 200 includes a switching device SW. 8+ and SW 8- This is used to selectively couple the positive and negative inputs of the PGA 230 of the first BBF 210 and the PGA 270 of the second BBF 250 together, respectively. Furthermore, the BBF 200 includes a switching device SW. 12+ and SW 12- It is used to selectively couple the negative and positive outputs of the PGA 230 of the first BBF 210 and the PGA 270 of the second BBF 250 together, respectively.

[0073] BBF 200 also includes switchgear (SW). 4+ SW 4- SW 5+ and SW 5- This is used to selectively couple the RC feedback network of the TIA 220 of the first BBF 210 and the RC feedback network of the TIA 260 of the second BBF 250 to the corresponding inputs / outputs of the TIA 220 and TIA 260. Additionally, switch SW... 4+ SW 4- SW 5+ and SW 5- It can be configured to selectively couple the RC feedback network of the TIA 220 of the first BBF 210 and the RC feedback network of the TIA 260 of the second BBF 250 together, for example when the switch SW 3+ SW 3- SW 7+ and SW 7- When properly operated, the BBF 200 also includes a switchgear SW. 9+ SW 9- SW 10+ and SW 10- This is used to selectively couple the RC feedback network of the PGA 230 of the first BBF 210 and the RC feedback network of the PGA 270 of the second BBF 250 to the corresponding inputs / outputs of the PGA 230 and 270. Additionally, switch SW... 9+ SW 9- SW 10+ and SW 10- It can be configured to selectively couple the RC feedback network of the PGA 230 of the first BBF210 and the RC feedback network of the PGA 270 of the second BBF 250 together, for example when switch SW. 8+ SW 8- SW12+ and SW 12- When properly operated, the BBF 200 also includes a switchgear SW. 6+ and SW 6- This allows for the selective coupling of the differential output of the first internal stage of the TIA 220 to the differential output of the first internal stage of the TIA 260. Similarly, the BBF 200 also includes a switching device SW. 11+ and SW 11- This allows the differential output of the first internal stage of the PGA 230 to be selectively coupled to the differential output of the first internal stage of the PGA 270.

[0074] BBF 200 also includes switchgear (SW). 2+ and SW 2- The resistor groups 252+ and 252- of the second BBF 250 are selectively coupled to the positive and negative inputs of the TIA 260, respectively. Although not explicitly shown, the BBF 200 may include switching devices to selectively couple / decouple the variable resistors R24+, R24-, R25+, and R25- of the second BBF 250 from the first BBF 210.

[0075] Figure 2B The illustration shows a schematic diagram of a programmable baseband filter 200 in a first configuration according to another aspect of the present disclosure. In the first configuration, the first BBF 210 and the second BBF 250 operate independently of each other and respectively respond to separate input signals V. i1+ / V i1- and V i2+ / V i2- (For example, simultaneously) filtering is performed to generate a separate output signal V. o1+ / V o1- and V o2+ / V o2- Therefore, in the first configuration, the switchgear SW 1+ / SW 1- SW 3+ / SW 3- SW 6+ / SW 6- SW 7+ / SW 7- SW 8+ / SW 8- SW 11+ / SW 11- and SW 12+ / SW 12- They are configured to be in the off state. These switching devices in the off state decouple the first BBF 210 from the second BBF 250.

[0076] Furthermore, in the first configuration, the switchgear SW 2+ / SW 2- SW 4+ / SW 4- SW 5+ / SW 5- SW 9+ / SW 9- and SW 10+ / SW 10- The switch SW is configured to be in the closed state. 2+ / SW 2- The differential input of the second BBF 250 is coupled to the differential input of the TIA 260. The switching device SW is in the closed state. 4+ / SW 4- and SW 5+ / SW 5- The RC feedback network C 23+ / R 23+ and C 23- / R 23- Inputs and outputs coupled to the TIA 260. Switching device SW in the closed state. 9+ / SW 9- and SW 10+ / SW 10- The RC feedback network C 26+ / R 26+ and C 26- / R 26- The inputs and outputs are coupled to the PGA 270. A first enable signal en1 and a second enable signal en2 are asserted to enable the TIA 260 and the PGA 270, respectively.

[0077] Figure 2C A schematic diagram of an example programmable baseband filter 200 in a second configuration according to another aspect of this disclosure is illustrated. In the second configuration, a first BBF 210 is selectively coupled to a second BBF 250 to utilize certain passive (resistor / capacitor) components and active (amplifier) ​​components of the second BBF 250. This can result in narrower (tighter) poles and higher stopband rejection, thereby achieving lower flicker noise. In the second configuration, the first BBF 210 is coupled to the input differential signal V. i1+ / V i1- Perform filtering to generate V o1+ / V o1- The output differential signal is provided by the first BBF 210, while the second BBF 250 does not filter the separated signal because it is only used to provide additional components to the first BBF 210 for filtering operations.

[0078] Therefore, in the second configuration, the switchgear SW1+ / SW 1- and SW 2+ / SW 2- Configured to be in the off state to allow the differential input of the second BBF 250 and capacitor C to be connected. 21 C 22+ / C 22- The resistor group 252+ / 252- is decoupled from the first BBF 210. Although not explicitly shown, in the second configuration, a variable resistor R may also be present to decouple the second BBF 250. 24+ / R 24- and R 25+ / R 25- A switchgear decoupled from the first BBF 210.

[0079] Furthermore, in the second configuration, the switchgear SW 3+ / SW 3- SW 4+ / SW 4- SW 5+ / SW 5- SW 6+ / SW 6- SW 7+ / SW 7- SW 8+ / SW 8- SW 9+ / SW 9- SW 10+ / SW 10- SW 11+ / SW 11- and SW 12+ / SW 12- The switch SW is configured to be in the closed state. 3+ / SW 3- The differential input of TIA 220 of the first BBF 210 is coupled to the differential input of TIA260 of the second BBF 250. The switching device SW is in the closed state. 4+ / SW 4- and SW 5+ / SW 5- The RC feedback network C 23+ / R 23+ and C 23- / R 23- Inputs and outputs coupled to the TIA 260. Switching device SW in the closed state. 6+ / SW 6- The differential output of the first internal stage of the TIA 220 is coupled to the differential output of the first internal stage of the TIA 260. The switching device SW is in the closed state.7+ / SW 7- The differential output of TIA 220 of the first BBF 210 is coupled to the differential output of TIA 260 of the second BBF 250. A first enable signal en1 is asserted to enable TIA 260.

[0080] Furthermore, in the second configuration, the switch SW is in the closed state. 8+ / SW 8- The differential input of the PGA230 of the first BBF 210 is coupled to the differential input of the PGA270 of the second BBF 250. The switching device SW is in the closed state. 9+ / SW 9- and SW 10+ / SW 10- The RC feedback network C 26+ / R 26+ and C 26- / R 26- Inputs and outputs coupled to the PGA 270. Switching device SW in the closed state. 11+ / SW 11- The differential output of the first internal stage of the PGA 230 is coupled to the differential output of the first internal stage of the PGA 270. And the switching device SW is in the closed state. 12+ / SW 12- The differential output of PGA 230 of the first BBF 210 is coupled to the differential output of PGA 270 of the second BBF 250. A second enable signal en2 is asserted to enable PGA 270.

[0081] Figure 2D A schematic diagram of an example programmable baseband filter 200 in a third configuration according to another aspect of this disclosure is illustrated. In the third configuration, a first BBF 210 is selectively coupled to a second BBF 250 to borrow certain passive (resistor / capacitor) components of the second BBF 250 without borrowing the active (amplifier) ​​components of the second BBF 250. Borrowing passive components from the first BBF 210 can result in narrower (tighter) poles and higher stopband rejection, and not borrowing active components can improve power savings because the TIA 260 and PGA 270 of the second BBF 250 can be disabled. In the third configuration, the first BBF 210 is coupled to the input differential signal V. i1+ / V i1- Perform filtering to generate V o1+ / V o1- The output is a differential signal, while the second BBF250 does not filter the separated signal because it is only used to provide additional components to the first BBF210 for filtering operations.

[0082] Therefore, in the third configuration, the switchgear SW 1+ / SW 1- and SW 2+ / SW 2- Configured to be in the off state to allow the differential input of the second BBF 250 and capacitor C to be connected. 21 C 22+ / C 22- Decouple resistor group 252+ / 252- from first BBF 210. Switching device SW 6+ / SW 6- and SW 11+ / SW 11- It is also configured to be in the off state to decouple the differential outputs of the first internal stage of TIA 220 and the first internal stage of PGA 230 from the differential outputs of the first internal stage of TIA 260 and the first internal stage of PGA 270, respectively. The first enable signal en1 and the second enable signal en2 are not asserted, and therefore disable TIA 260 and PGA 270, respectively. Although not explicitly shown, in the third configuration, a variable resistor R for the second BBF 250 may also be present. 24+ / R 24- and R 25+ / R 25- A switchgear decoupled from the first BBF 210.

[0083] Furthermore, in the third configuration, the switchgear SW 3+ / SW 3- SW 4+ / SW 4- SW 5+ / SW 5- SW 7+ / SW 7- SW 8+ / SW 8- SW 9+ / SW 9- SW 10+ / SW 10- and SW 12+ / SW 12- The switch SW is configured to be in the closed state. 3+ / SW 3- SW 4+ / SW 4- SW 5+ / SW 5- and SW 7+ / SW 7- The RC feedback network C of the second BBF 250 23+ / R23+ and C 23- / R 23- The RC feedback network C of the first BBF 210 is respectively connected to the first BBF 210. 13+ / R 13+ and C 13- / R 13- Parallel coupling. Furthermore, the switchgear SW is in a closed state. 8+ / SW 8- SW 9+ / SW 9- SW 10+ / SW 10- and SW 12+ / SW 12- The RC feedback network C of the second BBF 250 26+ / R 26+ and C 26- / R 26- The RC feedback network C of the first BBF 210 is respectively connected to the first BBF 210. 16+ / R 16+ and C 16- / R 16- Parallel coupling.

[0084] Figure 2E A schematic diagram of an example programmable baseband filter 200 in a fourth configuration according to another aspect of this disclosure is illustrated. In the fourth configuration, a first BBF 210 is selectively coupled to a second BBF 250 to borrow the active (amplifier) ​​components of the second BBF 250 without borrowing the passive (resistor / capacitor) components of the second BBF 250. This can result in lower flicker noise because the effective device size increases (e.g., doubles). Furthermore, the borrowing of passive components may not be necessary because the filter poles do not need to be as narrow (tight) in frequency, and a single-pole configuration may be sufficient to achieve the desired stopband rejection. In the fourth configuration, the first BBF 210 is coupled to the input differential signal V. i1+ / V i1- Perform filtering to generate V o1+ / V o1- The output differential signal is provided by the first BBF 210, while the second BBF 250 does not filter the separated signal because it is only used to provide additional components to the first BBF 210 for filtering operations.

[0085] Therefore, in the fourth configuration, the switchgear SW 1+ / SW 1- and SW 2+ / SW 2- Configured to be in the off state, with the differential input of the second BBF 250 and capacitor C 21 C 22+ / C 22-Decouple resistor group 252+ / 252- from first BBF 210. Switching device SW 4+ / SW 4- and SW 5+ / SW5 is configured to be in the disconnected state to disconnect the RC feedback network C of the second BBF 250. 23+ / R 23+ and C 23- / R 23- Decoupled from the first BBF 210. Similarly, the switchgear SW 9+ / SW 9- and SW 10+ / SW 10- Configured to be in the disconnected state to disconnect the RC feedback network C of the second BBF 250. 26+ / R 26+ and C 26- / R 26- Decoupled from the first BBF 210. Although not explicitly shown, in the fourth configuration, a variable resistor R for the second BBF 250 may also be present. 24+ / R 24- and R 25+ / R 25- A switchgear decoupled from the first BBF 210.

[0086] Furthermore, in the fourth configuration, the switchgear SW 3+ / SW 3- SW 6+ / SW 6- SW 7+ / SW 7- SW 8+ / SW 8- SW 11+ / SW 11- and SW 12+ / SW 12- The switch SW is configured to be in the closed state. 3+ / SW 3- The differential input of the first BBF210's TIA220 is coupled to the differential input of the second BBF250's TIA260. The switching device SW is in the closed state. 6+ / SW 6- The differential output of the first internal stage of the TIA 220 is coupled to the differential output of the first internal stage of the TIA 260. The switching device SW is in the closed state. 7+ / SW 7- The differential output of TIA 220 of the first BBF 210 is coupled to the differential output of TIA 260 of the second BBF 250. The switching device SW is in the closed state. 8+ / SW 8- The differential input of the PGA230 of the first BBF 210 is coupled to the differential input of the PGA270 of the second BBF 250. The switching device SW is in the closed state. 11+ / SW 11- The differential output of the first internal stage of the PGA 230 is coupled to the differential output of the first internal stage of the PGA 270. And the switching device SW is in the closed state. 12+ / SW 12- The differential output of the PGA 230 of the first BBF 210 is coupled to the differential output of the PGA 270 of the second BBF 250. A first enable signal en1 and a second enable signal en2 are asserted to enable the TIA 260 and PGA 270, respectively.

[0087] Figure 2F A schematic diagram of an example programmable baseband filter 200 in a fifth configuration according to another aspect of this disclosure is illustrated. The fifth configuration is similar to the second configuration discussed in detail previously, wherein the first BBF 210 is selectively coupled to the second BBF 250 to borrow certain passive (resistor / capacitor) components and active (amplifier) ​​components of the second BBF 250, for example, to configure its performance for narrower (tighter) poles and higher stopband rejection and lower flicker noise.

[0088] For example, in the case of processing GSM signals, to achieve narrower (tighter) poles and higher stopband rejection performance, the baseband filter 200 is selectively coupled to the capacitor bank 290. Specifically, when the switching device SW... 13+ / SW 17+ and SW 13- / SW 17- When configured to be in a closed state, the RC feedback network C of the first BBF 210 13+ / R 13+ and C 13- / R 13- And the RC feedback network C of the second BBF250 23+ / R 23+ and C 23- / R 23- Through these switching devices and capacitor C of capacitor bank 290 + and C - Parallel coupling. Capacitor C + / C - Lower the frequency of the poles of baseband filter 200. Capacitor C + / C - This can represent a single capacitor or multiple capacitors. In some embodiments, capacitor C... + / C -It is variable and / or includes multiple switchable components.

[0089] Figure 2G A schematic diagram of an example programmable baseband filter 200 in a sixth configuration according to another aspect of this disclosure is illustrated. The sixth configuration is also similar to the second configuration discussed in detail previously, wherein the first BBF 210 is selectively coupled to the second BBF 250 to borrow certain passive (resistor / capacitor) components and active (amplifier) ​​components of the second BBF 250, for example, to configure its performance for narrower (tighter) poles and higher stopband rejection as well as lower flicker noise.

[0090] To achieve high stopband rejection performance at lower frequencies, the first BBF 210 can also be selectively coupled to the second BBF 250 to utilize the input passive components of the second BBF 250. In this regard, the switching device SW... 1+ / SW 1- and SW 2+ / SW 2- It is configured to be in the closed state to open the second BBF 250 capacitor C. 21 C 22+ / C 22- The resistor group 252+ / 252- is coupled to the first BBF 210. Although in this example, the variable resistor R of the second BBF 250... 24+ / R 24- and R 25+ / R 25- These resistors are shown as decoupled from the first BBF 210, but it should be understood that they can be coupled to the first BBF 210 via corresponding switching devices.

[0091] It should be understood that not all configurations of BBF 200 are described and illustrated. For example, the switching device can be configured such that BBF 210 can be selectively coupled to a second BBF 250 to borrow resistor bank 252+ / 252- without borrowing TIA260 and / or the feedback network of TIA 260. As another example, the switching device can be configured such that BBF 210 can be selectively coupled to a second BBF 250 to borrow resistor R. 24+ / R 24- and R 25+ / R 25- Regardless of whether other components of the BBF 250 are used.

[0092] It should be further understood that not all described configurations must be provided by the implementation of baseband filter 200, and therefore one or more of the connections and / or switching devices illustrated to couple BBF 210 to BBF 250 may be omitted. For example, in some embodiments, the switching device (e.g., SW) that selectively couples the intermediate stage of TIA 220 to TIA 260 may be omitted. 6+ / SW 6- In other embodiments, the connections between these stages are completely omitted, and therefore the intermediate stages of TIA 220 will not be selectively coupled to the intermediate stages of TIA 260. As another example, in some embodiments, it is not necessary to provide a switching device (e.g., SW) that selectively couples the input of PGA 230 to the input of PGA 270. 8+ / SW 8- Alternatively, in some embodiments, a switching device is not required to couple the feedback network of TIA 220 to the feedback network of TIA 260. Therefore, in some embodiments, any one or more switching devices described in BBF 200 may be omitted, and thus the configuration they implement does not need to be available in all embodiments. This omission of switching devices may be caused by the permanent coupling or decoupling of individual active / passive components of the second BBF 250 from the first BBF 210.

[0093] Figure 3A The diagram illustrates the spectrum (shaded area) and frequency response H(f) (dashed line) of an example received channel CHN 1 and a single-pole baseband filter in zero intermediate frequency (ZIF) reception mode according to another aspect of this disclosure. In ZIF reception mode, the frequency of the LO is substantially the same as the carrier frequency of the channel of interest (such as CHN 1). Therefore, when the associated mixer mixes the channel of interest CHN 1 with the LO, the resulting lower frequency component of the mixing operation is centered at zero hertz (0 Hz) or DC, as illustrated by the shaded area representing CHN 1. The passband of the filter frequency response H(f) can be at pole f. p The region between the two points is essentially flat, and the roll-off of the filter frequency response H(f) can be at the poles f respectively. p The sloping sections below and above.

[0094] The transmit channel associated with the received CHN 1 may include a transmit signal that can leak into the received CHN 1 via antenna-to-antenna coupling or transmitter-to-receiver coupling and can be considered an interference signal relative to the received CHN 1. As illustrated, the CHN 1 transmit (Tx) interference is separated from the spectrum of CHN 1 by a certain frequency offset. A baseband filter (BBF) configured to filter CHN 1 to remove upper frequency components and other unwanted signals (such as CHN 1 Tx interference) can be configured as a single-pole filter. p The frequency response H(f) (represented by a dashed line around the spectrum of CHN 1) is such that its stopband suppression at the frequency of the CHN 1 Tx interference is sufficient to reduce its power level so that the interference does not significantly affect the SNR of CHN 1.

[0095] Figure 3B The illustration shows a graph of the spectrum (shaded area) and frequency response H(f) (dashed line) of another example received channel and single-pole baseband filter in Offset Zero Intermediate Frequency (OZIF) receive mode according to another aspect of this disclosure. In OZIF receive mode, both channels (e.g., CHN 1 to CHN 2) are down-converted and filtered by the same mixer and baseband filter. Since both channels are processed by the same hardware, the OZIF mode of the receive channel can save significant IC area and power. In OZIF mode, the LO frequency is set between the spectrum of the first channel CHN 1 and the second channel CHN 2 (e.g., in the middle of the spectrum of the first channel CHN 1 and the second channel CHN 2). Therefore, when the associated mixer mixes the channel of interest with the LO, the resulting lower frequency component of the mixing operation is centered at 0 Hz or DC, as illustrated by the shaded areas representing CHN 1 and CHN 2.

[0096] The transmit channel associated with the received CHN 1 generates a signal that is considered interference relative to the received CHN 1. As illustrated, the CHN 1 transmit (Tx) interference is separated from the spectrum of CHN 1 by a certain frequency offset. The baseband filter (BBF), previously configured as a single pole to filter CHN 1 to remove upper frequency components and other unwanted signals such as CHN 1 Tx interference, must now also filter CHN 2 to remove such unwanted signals from the frequency band of CHN 2. Note that the CHN 1 Tx interference can be close to the frequency band of CHN 2 in frequency and has a single pole f with a frequency response H(f) sufficient to suppress CHN 1 Tx interference in ZIF mode. p BBF may not be sufficient to suppress interference with CHN 2.

[0097] Figure 3CThe illustration shows another example of a channel and complex pole f in an offset zero intermediate frequency (OZIF) receiver mode according to another aspect of this disclosure. p The graph shows the spectrum (shaded area) and frequency response H(f) (dashed line) of the baseband filter. As shown in the graph, a solution to suppress CHN 1 Tx interference to prevent SNR degradation in channel 2 could be to use a filter with higher poles. Compared to a single-pole filter, a filter with higher poles has a higher pole frequency f. p In addition, it can have a steeper descent. This is in Figure 3B The diagram shows that the frequency response H(f) of the single-pole filter has a roll-off on the negative frequency side, which reduces the intensity of the CHN 1 Tx interference by, for example, half; while... Figure 3C As shown, the frequency response H(f) of the complex pole filter has a roll-off on the negative frequency side, which reduces the intensity of the CHN 1 Tx interference by more than half.

[0098] One approach is to use a dual second-order filter with two poles. However, using a dual second-order filter has drawbacks. This filter typically requires two additional operational amplifiers and RC poles to achieve the desired stopband rejection. This can lead to a significant increase in the IC footprint required for implementation, which is not considered a cost-effective approach. Furthermore, implementing a dual second-order filter for each OZIF receiver may require tedious calibration to reduce residual sidebands (RSB) due to downconversion of the desired channel image and amplitude and phase mismatches in the LO applied to the I and Q mixers.

[0099] Figure 4A A schematic diagram of a programmable baseband filter (BBF) 400 according to another aspect of this disclosure is illustrated. In general, the programmable BBF 400 includes switching devices for configuring the filter to have a single pole, a double pole, or a complex pole. When the programmable (or configured) BBF 400 filters a signal in ZIF mode, a single-pole configuration can be used because a single-pole filter may be sufficient to provide the required interference suppression. When the programmable BBF 400 filters a signal in OZIF mode, a complex-pole configuration can be programmed (or configured) because a complex pole may be required to provide the required interference suppression.

[0100] Specifically, the programmable BBF 400 includes a differential input configured to receive an input differential signal V from, for example, a corresponding mixer of receiver 100. i1+ / V i1- The BBF 400 is configured to process the input differential signal V. i1+ / V i1- Filtering is performed to generate the output differential signal V at the differential output. o1+ / Vo1- The programmable BBF 400 includes capacitors C coupled across the positive and negative sides of the differential input. 11 The BBF 400 also includes a capacitor C coupled between the positive side of the differential input and ground. 12+ And another capacitor C coupled between the negative side of the differential input and ground. 12- Furthermore, the programmable BBF 400 includes a first resistor group 412+ coupled between the positive side of the differential input and the positive input of the first-stage amplifier 420, which can be configured as a transimpedance amplifier (TIA). Additionally, the programmable BBF 400 includes a second resistor group 412 coupled between the negative side of the differential input and the negative input of the TIA 420.

[0101] The programmable BBF 400 includes a first RC feedback network, which includes resistor R 13+ A capacitor C (which can be variable) is connected in parallel between the negative output and positive input of the TIA 420. 13+ (This can be variable). Similarly, the BBF 400 also includes a second RC feedback network, which includes resistor R... 13- A capacitor C (which can be variable) is connected in parallel between the positive output and negative input of the TIA 420. 13- (Can be variable). Includes RC feedback network C 13+ / R 13+ and C 13- / R 13- The TIA 420, the first resistor group 412+ and the second resistor group 412-, and the capacitor C 11 C 12+ and C 12- This forms the first filter stage of the programmable BBF 400. It allows for adjustments to the resistors in resistor banks 412+ and 412-, and the feedback capacitor C. 13+ / C 13- The capacitor and feedback resistor R 13+ / R 13- The resistance is variable to set the poles of the first filter stage.

[0102] The programmable BBF 400 also includes a variable resistor R series coupled between the negative output of the TIA 420 and the positive input of the second amplification stage 430. 14+ and R 15+ The second amplification stage 430 can be configured as a programmable gain amplifier (PGA). The programmable BBF 400 also includes a variable resistor R series-coupled between the positive output of the TIA 420 and the negative input of the PGA 430. 14- and R 15-The programmable BBF 400 also includes capacitor C. 14 capacitor C 14 Including coupling to resistor R 14+ With R 15+ The first terminal of the first node between, and coupled to resistor R 14- With R 15- The second terminal of the second node is used to configure a BBF 400 with complex poles as further described herein. In the case of a single-ended filter, the second terminal of capacitor C14 can be coupled to ground.

[0103] The programmable BBF 400 also includes a third RC feedback network, which includes resistor R 16+ A capacitor C (which can be variable) is coupled in parallel to the negative output of the PGA 430. 16+ (This can be variable). Similarly, the programmable BBF400 also includes a fourth RC feedback network, which includes resistor R... 16- A capacitor C (which can be variable) is coupled in parallel to the positive output of the PGA 430. 16- (Can be variable). Capacitor C 16+ and C 16- They are then connected to the positive and negative inputs of the PGA430, respectively.

[0104] The PGA 430 includes differential outputs to generate a filtered differential output signal V. o1+ / V o1- The output differential signal V of receiver 100, such as the I-BBF 160-1I or Q-BBF 160-1Q. oI1+ / V oI1- or V oQ1+ / V oQ1- Including RC feedback network C 16+ / R 16+ and C 16- / R 16- PGA 430, resistor R 14+ / R 15+ and R 14- / R 15- and capacitor C 14 This forms the second filter stage of the BBF 400. Resistor R can be used to... 14+ / R 15+ and R 14- / R 15- The resistor and the feedback capacitor C 16+ / C 16- The capacitor and feedback resistor R 16+ / R 16-The resistance is variable to set the poles (multiple) of the second filter stage.

[0105] To program the programmable BBF 400 between single-pole and complex-pole configurations, the BBF 400 includes a switching device SW. 14+ / SW 14- SW 15+ / SW 15- And optional SW 16+ / SW 16- Switchgear SW 14+ Connected to resistor R 16+ Between the positive input of the PGA 430 and the switching device SW. 15+ Connected to resistor R 16+ With variable resistor R 14+ and R 15+ Between the first nodes. Similarly, the switching device SW 14- Connected to resistor R 16- Between the negative input of the PGA 430 and the switching device SW. 15- Connected to resistor R 16- With variable resistor R 14- and R 15- Between the second node. Although the switchgear SW 14+ SW 14- SW 15+ SW 15- exist Figure 4A -In Figure 4G, the devices are shown as separate, but the switching device SW 14+ and SW 15+ It can be configured as a multi-throw switch, and / or a switching device SW. 14- and SW 15- It can be configured as a multi-throw switch.

[0106] like Figure 4A The programmable BBF 400 depicted is in a single-pole configuration, for example, to process signals according to the ZIF receive operation mode. In the single-pole configuration, the switching device SW 14+ / SW 14- The switch SW is configured to be in the closed state. 15+ / SW 15- It is in the off state, and the switching device SW 16+ / SW 16- (If present) can be configured to be in a disconnected state. Therefore, in this configuration, the PGA 430 includes an RC feedback network R connected between the negative output and positive input of the PGA 430. 16+ / C 16+and the RC feedback network R connected between the positive output and negative input of the PGA 430. 16- / C 16- This is a single-pole configuration because the RC feedback network provides a single pole.

[0107] If the switching device SW 16+ / SW 16- If it does not exist, then capacitor C 14 It works because it crosses resistor R 14+ and R 15+ The first node between R 14- and R 15- The second node between them is coupled. However, in this configuration, the capacitor C... 14 The poles formed can be far from the dominant pole formed by the RC feedback network in terms of frequency, so as not to have too much impact on the frequency response and roll-off of the BBF 400.

[0108] Figure 4B The illustration shows a schematic diagram of a programmable BBF 400 in a complex pole configuration according to another aspect of this disclosure. In the complex pole (multiple poles) configuration, the switching device SW 14+ / SW 14- The switching device SW is configured to be in the off state. 15+ / SW 15- Configured to be in the closed state, and the switching device SW 16+ / SW 16- (If present) is configured to be in a closed state. Accordingly, in this configuration, the PGA 430 includes a capacitor C in the RC feedback network connected between the negative output and the positive input of the PGA 430. 16+ and connected to the negative output and resistor R 14+ and R 15+ The resistor R between the first node of the RC feedback network 16+ Similarly, in this configuration, the PGA 430 includes a capacitor C in an RC feedback network connected between the positive output and negative input of the PGA 430. 16- and connected to the positive output and resistor R 14- and R 15- The resistor R between the second node and the RC feedback network 16- .

[0109] In this configuration, regardless of the switching device SW 16+ / SW 16- Does capacitor C exist? 14 All are connected to the first node (at resistor R) 14+ and R 15+(between) and the second node (in R) 14- and R 15- Between. In this configuration, the second filter stage of the programmable BBF 400 is configured to include a Rauch filter with complex poles to provide improved stopband rejection, for example, to suppress transmit (Tx) interference associated with the first channel adjacent to the second channel in OZIF receive operation mode. Additional switching devices are implemented without significantly increasing IC footprint; thus, single-pole or complex-pole filtering is provided without a noticeable increase in cost.

[0110] Although the filters have been described as differential filters in the previous examples, it should be understood that techniques for selectively coupling filters together or selectively reconfiguring filters between single-pole and multi-pole configurations are applicable to single-ended filters. Furthermore, while the filters have been described as having two stages in the previous examples, it should be understood that techniques for selectively coupling filters together or selectively reconfiguring filters between single-pole and multi-pole configurations are applicable to filters with one or more stages. Additionally, although not explicitly shown, a controller may be provided to configure the state of the switching devices and the resistance and capacitance of the variable resistors and capacitors to set the filters(s) to any of the previously described configurations.

[0111] Figure 5 A flowchart of an example method 500 for filtering a signal according to another aspect of this disclosure is illustrated. Method 500 includes: operating a first filter to filter a first input signal to generate a first output signal (block 510). Example components for operating the first filter to filter the first input signal to generate the first output signal include a switching device of the first BBF 210, a resistor / capacitor, and / or an amplifier.

[0112] Method 500 further includes: operating a second filter to filter the second input signal to generate a second output signal (block 520). Example components for operating the second filter to filter the second input signal to generate the second output signal include switching devices, resistors / capacitors, and / or amplifiers of the second BBF 250. This is in the case where the first BBF 210 and the second BBF 250 independently filter separate signals (such as separate channels or main channels and MIMO channels).

[0113] Method 500 additionally includes selectively coupling (e.g., merging) at least a portion of the second filter to the first filter to filter the third input signal to generate a third output signal (block 530). Example components for selectively coupling at least a portion of the second filter to the first filter to filter the third input signal to generate the third output signal include any switching device in a switching device that selectively couples the first BBF 210 and the second BBF 250 together, wherein the resulting selectively coupled filter filters the third input signal to generate the third output signal.

[0114] Figure 6 The illustration shows a flowchart of another example method 600 for filtering a signal according to another aspect of this disclosure. Method 600 includes: operating a group of one or more switching devices to configure a filter to have a first group of one or more poles (block 610). Example components for operating a group of one or more switching devices to configure a filter to have a first group of one or more poles include: a switching device SW configuring BBF 400. 14+ / SW 14- and SW 15+ / SW 15- The controller for the state.

[0115] Method 600 further includes: filtering the first input signal using a filter configured with one or more poles of the first set to generate a first output signal (block 620). Example components for filtering the first input signal using a filter configured with one or more poles of the first set to generate the first output signal include: BBF 400 (or a portion thereof), wherein the switching device SW of BBF 400... 14+ / SW 14- and SW 15+ / SW 15- They are configured to be in a closed state and an open state, respectively.

[0116] Method 600 further includes: operating one or more sets of switching devices to configure the filter to have a second set of one or more poles (block 630). Example components for operating one or more sets of switching devices to configure the filter to have a second set of one or more poles include: a switching device SW configuring BBF 400. 14+ / SW 14- and SW 15+ / SW 15- The controller for the state.

[0117] Furthermore, method 600 includes filtering the second input signal using a filter configured with one or more second sets of poles to generate a second output signal (block 640). Example components for filtering the second input signal using a filter configured with one or more second sets of poles to generate the second output signal include: BBF 400 (or a portion thereof), wherein the switching device SW of BBF 400... 14+ / SW 14- and SW 15+ / SW 15- Configure them to be in the open and closed states respectively.

[0118] Figure 7 A block diagram of an example wireless communication device 700 according to another aspect of this disclosure is illustrated. The wireless communication device 700 includes one or more antennas 710 and a receiver (or transceiver) 720, wherein at least a portion of the receiver is configured according to a receiver 100 having any of the BBFs described herein. The wireless communication device 700 also includes baseband processing circuitry 730 configured to process signals from the receiver 720.

[0119] Figure 8 A schematic / block diagram of another example receiver 800 according to another aspect of this disclosure is illustrated. Receiver 800 is an example of a receiver including a first programmable baseband filter (such as the programmable filter 200 discussed previously) and a second programmable baseband filter (such as the programmable filter 400 discussed previously). Depending on the requirements for passband ripple and stopband rejection of the baseband filter, either the first or second programmable filter can be selected, and the selected filter can be programmed according to the passband ripple and stopband rejection requirements.

[0120] More specifically, receiver 800 includes at least one antenna 805, a low-noise amplifier (LNA) 810, a mixer 815, a local oscillator (LO) 820, and a baseband filter. The baseband filter includes a programmable filter 830 that is the same as or similar to the programmable filter 200 discussed in detail previously, and a programmable single-pole / complex-pole filter 840 similar to the programmable baseband filter 400 discussed in detail previously. Receiver 800 also includes a controller 850 for selecting which filter 830 or 840 will filter the signal output from mixer 815, and for programming the selected filter as discussed further herein.

[0121] At least one antenna 805 is coupled to the input of LNA 810. LNA 810 includes an output coupled to a first input of mixer 815. LO 820 includes an output coupled to a second input of mixer 815. Mixer 815 includes an output coupled to a first input of programmable filter 830 via switching device SW1, and coupled to the input of programmable single-pole / complex-pole filter 840 via another switching device SWM.

[0122] The programmable filter 830 includes a second input that can be coupled to another receiver (Rx) chain, such as another quadrature (I- or Q) receiver chain, a spatial receiver chain, or another channel receiver chain. The programmable filter 830 includes a first single-pole baseband filter 832 (which can be configured similarly to the previously discussed BBF 210) and a second single-pole filter 834 (which can be configured identically or similarly to the previously discussed BBF 250). The first single-pole filter 832 includes an input coupled to the other receiver (Rx) chain via a switching device SW2. The second single-pole filter 834 includes an input that serves as the first input to the programmable filter 830.

[0123] For filter coupling purposes, the programmable filter 830 includes a set of switching devices SW3 to SWK. For example, switching device SW3 selectively couples the inputs of single-pole filters 832 and 834 together, switching device SWK selectively couples the outputs of single-pole filters 832 and 834 together, and switching devices SW4 to SWK-1 (unspecified) selectively couple the internal nodes of single-pole filters 832 and 834 together. The outputs of single-pole filters 832 and 834 are coupled to downstream processing via switching devices SWK+1 and SWK+2, respectively. As previously described, downstream processing may include analog-to-digital conversion (ADC), demodulation, error correction decoding, etc.

[0124] As discussed in detail regarding baseband filter 200, single-pole filters 832 and 834 can operate independently of each other, such as when single-pole filter 832 filters the signal output from another receiver (Rx) chain and single-pole filter 834 filters the signal output from mixer 815. In this case, a set of switching devices SW3 to SWK are in the off state. Moreover, one or more of the single-pole filters 832 and 834 can be made inoperable or disabled independently. For example, single-pole filter 832 can be made inoperable or disabled by configuring switching devices SW2 to SWK+1 to be in the off state, and single-pole filter 834 can be made inoperable or disabled by configuring switching devices SW1, SW3 to SWK and SWK+2 to be in the off state.

[0125] Furthermore, as discussed in detail with respect to baseband filter 200, single-pole filters 832 and 834 can be selectively coupled. As discussed, a filter (832 or 834) can be selectively coupled to other filters (834 or 832) to utilize active components, passive components, or both active and passive components of the other filters (834 or 832).

[0126] For example, if the signal output from another receiver (Rx) chain is to be filtered by selectively coupled single-pole filters 832 and 834, then one or more of the switches SW2, SW3 through SWK, and SWK+1 are configured to be closed, and switches SW1 and SWK+2 are configured to be open. In this example, the signals upstream and downstream of switches SW2 and SWK+1 are used as the input and output of programmable filter 830, respectively.

[0127] Similarly, if the signal output from mixer 815 is to be filtered by selectively coupled single-pole filters 832 and 834, then one or more of the switches SW1, SW3 through SWK, and SWK+2 are configured to be closed, and switches SW2 and SWK+1 are configured to be open. In this example, the signals upstream and downstream of switches SW2 and SWK+2 are used as the input and output of programmable filter 830, respectively.

[0128] As discussed, the programmable single-pole / complex-pole filter 840 can be configured in the same or similar manner as the BBF 400. Therefore, the programmable single-pole / complex-pole filter 840 includes a set of internal switching devices SWM+1 to SWN-1 (not explicitly shown) to configure the filter as a single-pole or complex-pole filter. The programmable single-pole / complex-pole filter 840 includes an output coupled to downstream processing via the switching device SWN.

[0129] Based on passband ripple and stopband rejection requirements, controller 850 generates control signals for a set of switching devices SW1 to SWN to provide the desired filter response at the output of mixer 814 and / or the output of another receiver (Rx) chain. For example, if programmable filter 830 is selected to filter the signal output from mixer 815, controller 850 configures switching device SW1 to be closed and at least switching device SWM to be open. Furthermore, controller 850 configures a set of switching devices SW2 to SWK+2 to program filter 830 as previously described (e.g., operating single-pole filters 832 and 834 independently or in a selectively coupled configuration).

[0130] If the programmable single-pole / complex-pole filter 840 is selected to filter the signal output from the mixer 815, the controller 850 configures at least the switching device SW1 to the open state and the switching devices SWM and SWN to the closed state. Furthermore, the controller 850 configures a set of switching devices SWM+1 to SWN-1 to program (or configure) the filter 840 as described above (e.g., to operate it as a single-pole or complex-pole filter).

[0131] Figure 9 A schematic diagram of another example of a programmable baseband filter (BBF) 900 according to another aspect of this disclosure is illustrated. The programmable BBF 900 includes a first BBF 910 and a second BBF 950. Each of the BBFs 910 and 950 can be configured identically or similarly to BBF 400. That is, each of the BBFs 910 and 950 can be configured as a single-pole filter or a complex-pole filter, as discussed in detail with respect to BBF 400. Furthermore, similar to the filter component borrowing or filter coupling scheme of the programmable BBF 200, the programmable BBF 900 includes a set of switching devices such that one of the BBFs 910 or 950 can borrow one or more active and / or passive components from the other BBF 950 or BBF 910.

[0132] Therefore, the BBF 910 can operate independently of the BBF 950 to perform operations on the input signal V. i1+ / V i1- Single-pole or complex-pole filtering is used to generate the filtered output V. o1+ / V o1- In this configuration, the switching device used to selectively couple BBF 910 to BBF 950 can be configured to disconnect. Similarly, BBF 950 can operate independently of BBF 910 to perform actions on the input signal V. i2+ / V i2- Single-pole or complex-pole filtering is used to generate the filtered output V. o2+ / V o2- In this configuration, the switching device used to selectively couple the BBF 950 to the BBF 910 can be disconnected. In some configurations, the operation of filtering signals separately from other BBF components or operations, either the BBF 910 or BBF 950, is described as a first operating mode.

[0133] As discussed in detail regarding BBF 200, one of the BBFs 910 or BBF 950 can be selectively coupled to another BBF 950 or BBF 910 to borrow one or more active and / or passive components from the other BBF 950 or BBF 910. For example, BBF 910 can be operated to selectively couple BBF 910 to one or more active and / or passive components of BBF 950 to the input signal V. i1+ / V i1- Perform filtering to generate the filtered output V o1+ / V o1- In this configuration, one or more of the switching devices used to selectively couple the BBF 910 to the BBF 950 can be configured to be in the closed state, and the remaining switching devices (if any) can be configured to be in the open state. In some configurations, this operation can be described as a second operating mode.

[0134] Similarly, the BBF 950 can be operated to selectively couple the BBF 950 to one or more active and / or passive components of the BBF 910 to the input signal V. i2+ / V i2- Perform filtering to generate the filtered output V o2+ / V o2- In this configuration, one or more of the switching devices used to selectively couple BBF 950 to BBF 910 can be configured to be in a closed state, and the remaining switching devices (if any) can be configured to be in an open state. In some configurations, this operation can be described as a third operating mode. In some embodiments, when filter 900 operates in a second or third mode, neither BBF 910 nor BBF 950 is controlled to perform complex pole filtering (e.g., switching device SW). 14+ / SW 14- Configured to be in the closed state, and the switching device SW 15+ / SW 15- (Configured to be in a disconnected state).

[0135] The following provides an overview of aspects of this disclosure:

[0136] Aspect 1: A filter comprising: a first amplifier; a first resistor and a second resistor, coupled in series between a first input of the filter and a first input of the first amplifier; a first feedback capacitor coupled between a first output of the first amplifier and the first input; a capacitor coupled to a first node between the first resistor and the second resistor; a first feedback resistor coupled to the first output of the first amplifier; and a first group of one or more switching devices configured to selectively couple the first feedback resistor to the capacitor and selectively connect the first feedback resistor to the first input of the first amplifier. The capacitor may be selectively or permanently coupled to the first node.

[0137] Aspect 2: The filter according to aspect 1, wherein the capacitor is coupled to ground.

[0138] Aspect 3: The filter according to aspect 1, wherein the first group of one or more switching devices includes: a first switch configured to selectively connect the first feedback resistor to the first input of the first amplifier; and a second switch configured to selectively connect the first feedback resistor to the first node.

[0139] Aspect 4: The filter according to aspect 3, wherein the first group of one or more switching devices further includes a third switch configured to selectively connect the capacitor to the first node.

[0140] Aspect 5: The filter according to aspect 3, wherein the capacitor is directly and permanently connected to the first node.

[0141] Aspect 6: The filter according to any one of Aspects 1-5 further includes: a third resistor and a fourth resistor, coupled in series between a second input of the filter and a second input of the first amplifier; a second feedback capacitor, coupled between a second output of the first amplifier and the second input; a second feedback resistor, coupled to the second output of the first amplifier; and a second set of one or more switching devices configured to selectively couple the second feedback resistor to the capacitor and selectively connect the second feedback resistor to the second input of the first amplifier. The capacitor may be permanently or selectively coupled to a second node between the third resistor and the fourth resistor.

[0142] Aspect 7: The filter according to aspect 6, wherein the first set of switching devices includes a first switching device configured to selectively decouple the capacitor from the first node, and wherein the second set of switching devices includes a second switching device configured to selectively decouple the capacitor from the second node.

[0143] Aspect 8: The filter according to aspect 6 or 7, wherein: the first input of the first amplifier includes the positive input of the first amplifier; the first output includes the negative output of the first amplifier; the second input of the first amplifier includes the negative input of the first amplifier; and the second output includes the positive output of the first amplifier.

[0144] Aspect 9: The filter according to any one of aspects 1-8, wherein the first amplifier includes a programmable gain amplifier (PGA).

[0145] Aspect 10: The filter according to any one of aspects 1-9 further includes a second amplifier coupled between the first input of the filter and the first resistor and the second resistor.

[0146] Aspect 11: A filter according to any one of aspects 1-10, wherein the filter includes a baseband filter.

[0147] Aspect 12: A method comprising: operating a group of one or more switching devices to configure a filter to have a first group of one or more poles; filtering a first input signal with the filter configured with the first group of one or more poles to generate a first output signal; operating the group of one or more switching devices to configure the filter to have a second group of one or more poles; and filtering a second input signal with the filter configured with the second group of one or more poles to generate a second output signal.

[0148] Aspect 13: According to the method of aspect 12, wherein the first group of one or more poles includes a single pole.

[0149] Aspect 14: The method according to aspect 12 or 13, wherein the second set of one or more poles includes a plurality of poles.

[0150] Aspect 15: The method according to any one of aspects 12-14, wherein the second set of one or more poles includes complex poles.

[0151] Aspect 16: The method according to any one of aspects 12-15, wherein the filter configured with one or more poles of the second group is configured as a Rauch filter.

[0152] Aspect 17: A filter comprising: a first amplifier having a differential input and a differential output; a first feedback resistor and a second feedback resistor, respectively coupled between the differential input and the differential output; and a plurality of switching devices configured to selectively couple the first feedback resistor to the second feedback resistor.

[0153] Aspect 18: The filter according to aspect 17, wherein the first feedback resistor is coupled to the second feedback resistor via a capacitor.

[0154] Aspect 19: The filter according to aspect 17 or 18, wherein the filter includes a baseband filter.

[0155] The foregoing description of this disclosure is provided to enable those skilled in the art to make or use this disclosure. Various modifications to this disclosure will be apparent to those skilled in the art, and the general principles defined herein can be applied to other variations without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not intended to be limited to the examples described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A filter, comprising: First amplifier; A first resistor and a second resistor are coupled in series between the first input of the filter and the first input of the first amplifier; A first feedback capacitor is connected between the first output of the first amplifier and the first input of the first amplifier; A capacitor is selectively or permanently coupled to a first node between the first resistor and the second resistor; A first feedback resistor is connected to the first output of the first amplifier; as well as A first group of one or more switching devices is configured to selectively connect the first feedback resistor to the capacitor and to selectively connect the first feedback resistor to the first input of the first amplifier.

2. The filter of claim 1, wherein the capacitor is coupled to ground.

3. The filter of claim 1, wherein the first group of one or more switching devices comprises: A first switch is configured to selectively connect the first feedback resistor to the first input of the first amplifier; And a second switch, configured to selectively connect the first feedback resistor to the first node.

4. The filter of claim 3, wherein the first group of one or more switching devices further comprises a third switch configured to selectively connect the capacitor to the first node.

5. The filter of claim 3, wherein the capacitor is directly and permanently connected to the first node.

6. The filter according to claim 1, further comprising: A third resistor and a fourth resistor are coupled in series between the second input of the filter and the second input of the first amplifier, wherein the capacitor is also permanently or selectively coupled to a second node between the third resistor and the fourth resistor; A second feedback capacitor is connected between the second output of the first amplifier and the second input of the first amplifier; A second feedback resistor is connected to the second output of the first amplifier; as well as A second group of one or more switching devices is configured to selectively connect the second feedback resistor to the capacitor and to selectively connect the second feedback resistor to the second input of the first amplifier.

7. The filter of claim 6, wherein the first set of switching devices includes a first switching device configured to selectively decouple the capacitor from the first node, and wherein the second set of switching devices includes a second switching device configured to selectively decouple the capacitor from the second node.

8. The filter according to claim 6, wherein: The first input of the first amplifier includes the positive input of the first amplifier; The first output includes the negative output of the first amplifier; The second input of the first amplifier includes the negative input of the first amplifier; and The second output includes the positive output of the first amplifier.

9. The filter of claim 1, wherein the first amplifier comprises a programmable gain amplifier (PGA).

10. The filter of claim 1, further comprising a second amplifier coupled between: The first input of the filter, and The first resistor and the second resistor.

11. The filter of claim 1, wherein the filter comprises a baseband filter.

12. A filtering method, comprising: Operate one or more sets of switching devices to configure the filter to have one or more first sets of poles; The first input signal is filtered using the filter configured with one or more poles of the first group to generate a first output signal; Operate the group of one or more switching devices to configure the filter to have a second set of poles; as well as The second input signal is filtered using the filter configured with the second set of poles to generate a second output signal, wherein the filter configured with the second set of poles includes capacitors coupled between the differential inputs of the filter.

13. The method of claim 12, wherein the first set of one or more poles comprises a single pole.

14. The method of claim 13, wherein the second set of poles includes complex poles.

15. The method of claim 13, wherein the filter configured with the second set of poles is configured as a Rauch filter.

16. The method of claim 15, wherein the second set of poles includes complex poles.

17. A filter, comprising: The first amplifier has differential input and differential output; The first feedback resistor and the second feedback resistor are respectively coupled to the differential output; Capacitor; A first plurality of switching devices are configured to selectively couple the first feedback resistor to a first input in the differential input or a first terminal of the capacitor; as well as The second plurality of switching devices are configured to selectively couple the second feedback resistor to a second input in the differential input or to a second terminal of the capacitor.

18. The filter of claim 17, wherein the filter comprises a baseband filter.

19. The filter according to claim 17, further comprising: A first resistor has a first terminal coupled to the first input and a second terminal selectively coupled to the first terminal of the capacitor; as well as The second resistor has a first terminal coupled to the second input and a second terminal selectively coupled to the second terminal of the capacitor.

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