Variable gain arrangement

Abstract

The invention relates to a variable gain arrangement of a receiver path configured to receive an input signal and apply a gain to the input signal to provide an output signal, the variable gain arrangement comprising: an input capacitor arrangement comprising a first input capacitor; a feedback capacitor arranged in series with the input capacitor arrangement, where the gain is based on a ratio of the first input capacitor to the feedback capacitor; and a gain switching device configured to provide an adjustment of the gain applied to the input signal by changing the ratio; an amplifier arranged in series with the input capacitor arrangement, the amplifier arranged in parallel with the feedback capacitor, the amplifier configured to provide the output signal; and a transient compensation capacitor arrangement comprising a first transient compensation capacitor wherein, upon the gain change, at least one transient compensation capacitor is immediately configured to be coupled to or decoupled from the feedback capacitor, and wherein at least one transient compensation capacitor is configured to be coupled to or decoupled from the feedback capacitor. Therefore, the transient stability effect caused by the gain change is compensated.

Description

Technical Field

[0001] The present disclosure relates to a variable gain arrangement. The present disclosure further relates to a gain arrangement comprising both the variable gain arrangement and the fixed gain arrangement, a radar system comprising the gain arrangement, and a motor vehicle comprising the radar system. Background Art

[0002] The proliferation of automotive radars in recent years has been significant and is expected to continue and accelerate as radar sensors become more advanced and cost-effective, driven by factors such as increasing safety regulations and the growing demand for advanced driver assistance systems (ADAS) features. Consequently, there is a need for greater emphasis on interference robustness. Radar signals emitted by nearby vehicles can interfere with the desired reflected signal and even overload the receiver path of the radar receiver. One way to prevent overload is to reduce the receiver gain so that more signal power can be processed before compression is reached. However, to maintain the same signal-to-noise ratio (SNR), this requires reducing the noise floor, which can be achieved only at the cost of a significant increase in the receiver's supply power. This increase in supply power conflicts with the desire to add more functionality on the same silicon die. Summary of the Invention

[0003] According to a first aspect of the present disclosure, there is provided a variable gain arrangement of a receiver path, the receiver path being configured to receive an input signal and apply a gain to the input signal to provide an output signal, the variable gain arrangement comprising: an input capacitor arrangement through which the input signal is transmitted, the input capacitor arrangement comprising a first input capacitor; a feedback capacitor arranged in series with the input capacitor arrangement, wherein the gain applied by the variable gain arrangement is based on a ratio of capacitances of the first input capacitor and the feedback capacitor; and a gain switching device configured to provide adjustment of the gain applied to the input signal by varying the ratio of the capacitance of the feedback capacitor to the input capacitor arrangement;

[0004] an amplifier arranged in series with the input capacitor arrangement, wherein the amplifier is further arranged in parallel with the feedback capacitor, and wherein the amplifier is configured to provide the output signal; and a transient compensation capacitor arrangement, the transient compensation capacitor arrangement comprising at least a first transient compensation capacitor, wherein upon a gain change of the variable gain arrangement, at least one transient compensation capacitor is configured to be coupled to or decoupled from the feedback capacitor such that transient stabilization effects caused by the gain change are compensated.

[0005] In one or more embodiments, the input capacitor arrangement can be a gain switching device, and wherein the input capacitor arrangement further includes: a second input capacitor, which is arranged in parallel with the first input capacitor; and a coupled input capacitor, wherein the coupled input capacitor is a capacitor through which the input signal is transmitted, wherein the first input capacitor and the second input capacitor are switchably arranged so that the functionality of the coupled input capacitor is switchably provided by one of the first input capacitor and the second input capacitor.

[0006] In one or more embodiments, the transient compensation capacitor arrangement may include a plurality of transient compensation capacitors, wherein, following the gain change imposed by the variable gain arrangement, the interconnection of the plurality of capacitors of the transient compensation capacitor arrangement and the feedback capacitor is dynamically reconfigured to achieve transient stabilization effect compensation.

[0007] In one or more embodiments, the first transient compensation capacitor may be a current injection capacitor switchably coupled to the feedback capacitor, wherein the current injection capacitor is configured to be coupled to the feedback capacitor immediately after a gain change of the output signal so that charge is injected into the feedback capacitor, wherein the charge injection achieves transient stabilization effect compensation.

[0008] In one or more embodiments, the first input capacitor and the second input capacitor may have different capacitances such that switching between the first input capacitor and the second input capacitor to define the coupled input capacitor causes the gain applied by the variable gain arrangement to change.

[0009] In one or more embodiments, the input capacitor arrangement may include: a first input path, the first input path including the first input capacitor; and a second input path, the second input path including the second input capacitor, wherein the first input path is arranged in parallel with the second input path, and wherein the first input path and the second input path are switchably coupled between the amplifier and a first voltage.

[0010] In one or more embodiments, the variable gain arrangement may additionally include a filter resistor arranged in parallel with both the amplifier and the feedback capacitor, wherein the filter resistor is configured to provide low frequency filtering of the input signal.

[0011] In one or more embodiments, the current injection capacitor may be coupled to the first voltage such that when not coupled to the feedback capacitive arrangement, the injection capacitor is charged by the first voltage.

[0012] In one or more embodiments, the current injection capacitor may be a first current injection capacitor coupled to a first node of the feedback capacitor, and wherein the transient compensation capacitor arrangement includes a second current injection capacitor coupled to a second node of the feedback capacitor, wherein the second current injection capacitor is switchably coupled to the feedback capacitor, wherein: in response to an increase in the gain of the variable gain arrangement, the feedback capacitor is configured to be coupled to the feedback capacitor; and in response to a decrease in the gain of the variable gain arrangement, the second feedback capacitor is configured to be coupled to the feedback capacitor.

[0013] According to a second aspect of the present disclosure, a gain arrangement of a receiver path is provided, the gain arrangement comprising a variable gain arrangement according to any one of the first aspects, wherein the input signal received by the variable gain arrangement is a variable gain input signal, and the output signal provided by the variable gain arrangement is a variable gain output signal, wherein the gain arrangement further comprises a fixed gain arrangement, the fixed gain arrangement being configured to receive a fixed gain input signal and apply a fixed gain to the fixed gain input signal to provide a fixed gain output signal, wherein the fixed gain arrangement is arranged in series with the variable gain arrangement, the fixed gain arrangement comprising: a third input capacitor, the fixed gain input signal being transmitted through the third input capacitor; a second feedback capacitor, the second feedback capacitor being arranged in series with the third input capacitor, wherein the gain applied by the fixed gain arrangement is based on a ratio of the capacitances of the second feedback capacitor and the third input capacitor; a second amplifier, the second amplifier being arranged in series with the third input capacitor, wherein the second amplifier is further arranged in parallel with the second feedback capacitor, and wherein the second amplifier is configured to provide the fixed gain output signal.

[0014] According to a third aspect of the present disclosure, a radar system is provided, wherein the radar path comprises: a transmitter path configured to transmit a plurality of transmit radar signals; and a receiver path configured to receive a plurality of reflected radar signals, wherein the receiver path comprises the gain arrangement of the second aspect.

[0015] According to a fourth aspect of the present disclosure, a motor vehicle comprising the radar system according to claim 11 is provided.

[0016] While the present disclosure is susceptible to various modifications and alternative forms, details thereof have been shown by way of example in the drawings and will be described in detail. However, it should be understood that other embodiments are possible besides the specific embodiments described. All modifications, equivalents, and alternative embodiments falling within the spirit and scope of the appended claims are also encompassed.

[0017] The above discussion is not intended to present every example embodiment or every implementation within the scope of the current or future claim sets. The accompanying drawings and the following detailed description also illustrate various example embodiments. The various example embodiments can be more fully understood by considering the following detailed description in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] One or more embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0019] Figure 1A shows an example embodiment of the gain arrangement of the present disclosure;

[0020] Figure 1B Shown after gain change Figure 1A Example embodiments of gain arrangements;

[0021] Figure 2 shows an alternative example embodiment of a gain arrangement according to the present disclosure;

[0022] Figure 3 shows yet another alternative example embodiment of the gain arrangement of the present disclosure;

[0023] Figure 4 An example radar system according to the present disclosure is shown; and

[0024] Figure 5 An example motor vehicle including a radar system according to the present disclosure is shown. DETAILED DESCRIPTION

[0025] Instead of increasing the power supply, interference robustness can be increased by detecting the arrival of jammers and responding by reducing receiver gain. Temporarily reducing receiver gain requires minimal power increase and is therefore a more economical solution. It should be noted that the receiver gain reduction will cost some SNR, but only for the duration of the jammer. The presence of a blocking signal will make it more difficult to extract the reflected signal from beneath the blocking signal, so losing some SNR will not significantly affect the radar system's operation.

[0026] Because in-band blocking signals can arrive in rapid bursts, the required gain changes also need to be made very quickly. In a typical IF amplifier, the receiver gain can be changed by switching the ratio of the circuit's input and feedback capacitors. Unfortunately, the gain change disrupts the DC balance of the capacitors, and these capacitors need to be stable for proper operation. While charge balance is less of an issue relative to DC content, it can cause problems with low-frequency signals, such as those caused by reflections of radar signals from a vehicle's bumper. Advantageously, gain changes involve only a change in the amplitude of the transfer function, not its phase. Therefore, in the time domain, the gain change simply involves scaling the output signal to a lower or higher value. The new output signal amplitude can be calculated based on the gain change and the instantaneous output signal value just before the gain switch.

[0027] While this article provides examples of challenges faced in automotive radar systems, it should be understood that any gain arrangement that adjusts its gain based on the ratio of the capacitances of two capacitors in a circuit may also suffer from undesirable stability effects. Therefore, the solutions provided herein may be applicable to a range of technology areas, such as AM radio, but may have particular benefits in the field of automotive radar systems.

[0028] In the context of radar systems, such as frequency modulated continuous wave (FMCW) radar systems, the receiver path typically includes a low-noise amplifier (LNA), a mixer, a baseband amplifier / filter, and an analog-to-digital converter (ADC). The received FMCW radar intermediate frequency signal has an uneven spectral distribution, with relatively strong signals at low frequencies (>10kHz) gradually fading to weaker signals at higher frequencies (<40MHz). To equalize the spectral content, a cascade of two high-pass filter stages can be used between the mixer and the ADC. These filter stages also provide gain to keep the ADC noise contribution low, thus providing the functionality of the gain arrangement.

[0029] In the context of FMCW radar systems, it can be advantageous to have low noise since the gain arrangement is directly connected to the mixer output. To provide this, a substantially "noiseless" capacitive feedback arrangement can be used. The gain is set by the ratio of the input capacitor to the feedback capacitor of the arrangement. High-pass filtering can also be provided by a resistor arranged in parallel with the feedback capacitor.

[0030] FMCW radars operate with a so-called chirp, which periodically returns to its initial frequency. During this return period, the radar transmits no signal, and the receiver does not need to receive any reflected signals. During the period when the frequency of the transmitted signal returns to its starting value, the gain arrangement / IF amplifier can be set to reset mode. When a new chirp begins, the reflected signal suddenly reappears as an input signal at the gain arrangement input. This sudden change causes an undesirable transient component in the IF amplifier that needs to gradually dissipate. Transient settling can be considered a separate signal that interferes with reception of the desired signal. For example, for a chirp with a total duration of 20 μs, the settling time can be approximately 4 μs.

[0031] Figure 1A An example gain arrangement 100 according to the present disclosure is shown. The gain arrangement comprises a fixed gain arrangement 101 (we would then need to remove the arrows shown in the feedback resistor 120 and capacitor 118) and a variable gain arrangement 102.

[0032] The variable gain arrangement 102 of the present disclosure is a variable gain arrangement 102 of a receiver path. The receiver path can be the receiver path of any device that receives an input signal and to which gain must be applied using the arrangement provided herein. For example, the receiver path can be the receiver path of an FMCW radar system, but can also be the receiver path of, for example, a different type of radar system or a wireless communication device.

[0033] The variable gain arrangement 102 is configured to receive an input signal and apply a gain to the input signal to provide an output signal. The gain is applied to the input signal by a component of the circuit (variable gain arrangement 102) that interacts with the input signal as the input signal passes therethrough. The input signal can be considered as a signal received at an input node 103 of the variable gain arrangement, and the output signal can be considered as a signal provided at an output node 104 of the variable gain arrangement. When the input signal passes through the variable gain arrangement 102, the signal will be affected by the components it passes through. Regardless of these changes, the input signal will be referred to herein as the input signal until it is provided as an output signal at the output node of the arrangement. It should be understood that, however, alternatively, the signal can be referred to as an intermediate signal, or alternative nomenclature can be used to represent its position or form when it passes through the variable gain arrangement 102 and reaches the output node 104.

[0034] Variable gain arrangement 102 includes an input capacitor arrangement 105 through which an input signal is transmitted. Input capacitor arrangement 105 includes a first input capacitor 106 and may include a second or any number of input capacitors 107 arranged in parallel with first input capacitor 106. First input capacitor 106 and second input capacitor 107 may have different capacitances. Input capacitors 106 and 107 of input capacitor arrangement 105 are switchably arranged so that the input signal is transmitted through only one of input capacitors 106 and 107 at a time. In one or more embodiments, capacitors may be added cumulatively rather than selecting only one capacitor at a time. The input capacitors 106 and 107 through which the input signal is transmitted may be referred to as input coupling capacitors of the input capacitor arrangement. Uncoupled input capacitors, i.e., input capacitors through which the input signal is not transmitted, may be coupled to a first voltage. The first voltage may be any suitable voltage equal to the DC voltage present at the input node of amplifier 111, and may, for example, be a common-mode voltage. The common-mode voltage may be provided by one or more amplifiers, each amplifier having its output node coupled to its own input node.

[0035] The capacitance of the first input capacitor 106 and the second, third, etc. input capacitors 107 may be different. Since the gain applied by the variable gain arrangement is based on the ratio of the input coupling capacitor and the feedback capacitor 108, switching between the first input capacitor 106 and the second input capacitor 107 may enable the variable gain functionality of the variable gain arrangement 102.

[0036] In one or more embodiments, such as the embodiment of FIG. 1 , the coupled input capacitor may include three or more input capacitors that are switchable between such that the functionality of the coupled input capacitor is provided by one of the plurality of at least three input capacitors.

[0037] In more detail, the input capacitor arrangement can include a first input path 109 including a first input capacitor 106 and a second input path 110 including a second input capacitor 107. First input path 109 and second input path 110 are arranged in parallel, and are switchable between first input path 109 and second input path 110. Specifically, first input path 109 and second input path 110 can be switched between being connected to: amplifier 111 and feedback capacitor 108; and a first voltage, such as a common-mode voltage. In embodiments having three or more input capacitors switchable between them, there can be correspondingly three or more input paths.

[0038] Variable gain arrangement 102 includes a gain switching device configured to adjust the gain applied to the input signal by varying the ratio of the capacitances of the feedback capacitor and the first input capacitor. Providing an input capacitor arrangement including multiple input capacitors that can be switched between provides a single way to adjust the gain applied by variable gain arrangement 102. In such embodiments, the gain switching device is an input capacitor arrangement. However, in other embodiments, the gain switching device may be provided by one or more other combinations of components. For example, instead of providing only a single feedback capacitor 108, a feedback capacitor arrangement may be provided that includes at least a first feedback capacitor 108, a second feedback capacitor, and a coupled feedback capacitor, wherein the first and second feedback capacitors are switchably arranged such that the functionality of the coupled feedback capacitor is switchably provided by one of the first and second input capacitors. In yet other embodiments, variable gain arrangement 102 may include both an input capacitor arrangement and a feedback capacitor arrangement, such that the gain applied to the input signal can be adjusted by varying which input capacitor is the coupled input capacitor, which feedback capacitor is the coupled feedback capacitor, or both the coupled input capacitor and the coupled feedback capacitor.

[0039] The variable gain arrangement 102 further comprises a feedback capacitor 108 arranged in series with the input capacitor arrangement 105. The ratio between this feedback capacitor 108 and the coupled input capacitor defines the voltage gain applied by the variable gain arrangement 102.

[0040] The variable gain arrangement 102 includes an amplifier 111 arranged in series with the input capacitor arrangement 105 and in parallel with the feedback capacitor 108. By virtue of the positioning of the amplifier 111 in the variable gain arrangement 102, the amplifier 111 provides an output signal. That is, the output node 104 of the variable gain arrangement 102 may be an output node of the amplifier 111.

[0041] The variable gain arrangement may further comprise a first resistor 112 arranged in parallel with both the feedback capacitor 108 and the amplifier 111, but arranged in series with the input capacitor arrangement 105, as shown. Figure 1A The first resistor may enable filtering of low frequency signals so as to provide high pass filter functionality to the variable gain arrangement 102 .

[0042] Variable gain arrangement 102 further includes a transient compensation capacitor arrangement 113. Transient compensation capacitor arrangement 113 includes at least a first transient compensation capacitor 114. Following a gain change in variable gain arrangement 102, at least one transient compensation capacitor 114 is configured to be coupled to or decoupled from feedback capacitor 108, thereby compensating for transient stabilization effects caused by the gain change. In other words, by providing one or more transient compensation capacitors in transient compensation capacitor arrangement 113 that can be selectively coupled to and decoupled from feedback capacitor 108, charge balancing can be implemented to provide transient compensation, thereby eliminating the need to wait for one or more transient signals induced by a sudden gain change to settle. When not coupled to feedback capacitor 108, the one or more transient compensation capacitors can be coupled to a first voltage or another voltage different from the first voltage. By being coupled to the voltage, one or each transient compensation capacitor can be charged, such that upon connection to feedback capacitor 108, the charge on the one or more transient compensation capacitors provides the charge balancing necessary to compensate for the generation of any undesirable transient signals.

[0043] exist Figure 1A In the example of FIG. 1 , the transient compensation capacitor arrangement includes three transient compensation capacitors 114, 115, and 116 coupled to a first voltage, which may be a common-mode voltage. It should be understood that in this embodiment, the number of transient compensation capacitors may be any number of transient compensation capacitors and need not specifically be three. By coupling these transient compensation capacitors to the first voltage, they charge when not otherwise coupled to the feedback capacitor.

[0044] Figure 1B The example shows a situation where the coupling capacitors of the input capacitor arrangement 105 have been changed by coupling the first input capacitor 106 to the amplifier 111 and decoupling the second input capacitor 107 from the amplifier 111. Since the capacitances of the first input capacitor 106 and the second input capacitor 107 are different, the change in the input capacitors, which are defined as coupling capacitors, results in a change in the gain of the variable gain arrangement. In response to the change in gain of the variable gain arrangement, the interconnection of the transient compensation capacitors 114, 115, 116 is adjusted so that they are decoupled from the first voltage and instead coupled to the feedback capacitor 108. The coupling of the transient compensation capacitors 114, 115, 116 to the feedback capacitor 108 provides the necessary balancing of charge and therefore compensation for any transient signals that might otherwise appear due to the sudden gain change of the variable gain arrangement 102 and need to be stabilized. It should be noted that Figure 1A and 1BThe example is arranged for a gain change of 2x. It should be noted that although the resistors and transistors are depicted as variable components in these figures, in the context of implementing a transient free gain change, these components will remain constant. Figure 1A and Figure 1B The general conditions that can be satisfied for gain change by capacitor redistribution (and vice versa) are:

[0045] a) The ratio of effective capacitance Cfb / Cs should match the old / new gain requirements; and

[0046] b) The voltage across the Cfb capacitor after redistribution should track the gain change.

[0047] Where Cfb is the total feedback capacitor capacitance, and Cs is the capacitance of the input coupling capacitor.

[0048] Figure 1A and 1B Also shown is a fixed-gain arrangement (FGA) 101, which may comprise a portion of the overall gain arrangement 100. Fixed-gain arrangement 101 includes an FGA input capacitor 117, which may alternatively be referred to as the input capacitor of fixed-gain arrangement 101. Fixed-gain arrangement 101 further includes an FGA feedback capacitor 118, which may alternatively be referred to as the feedback capacitor of fixed-gain arrangement 101. The ratio of FGA input capacitor 117 to FGA feedback capacitor 118 defines the gain applied by the fixed-gain arrangement. Fixed-gain arrangement 101 further includes an FGA amplifier 119 arranged in series with FGA input capacitor 117 and in parallel with FGA feedback capacitor 118. Fixed-gain arrangement 101 may further include an FGA resistor 120, wherein FGA resistor 120 is arranged in parallel with both FGA feedback capacitor 118 and FGA amplifier 119. FGA resistor 120 is also arranged in series with FGA input capacitor 117. The FGA resistor 120 provides high pass filtering equivalent to the first resistor.

[0049] The fixed gain arrangement 101 is arranged in series with the variable gain arrangement 102. Providing the variable gain arrangement 102 second in the series arrangement of the gain arrangements may provide an improved (reduced) signal to noise ratio compared to reversing the order of the gain arrangements. Figure 1A and 1B In the example shown, the fixed gain arrangement 101 is arranged before the variable gain arrangement 102 , but the fixed gain arrangement 101 may alternatively be arranged after the variable gain arrangement 102 .

[0050] Although Figure 1A and 1BThe embodiments represented in are functional, but they are not necessarily preferred, since each gain that needs to be compensated requires a different configuration of the transient stabilization capacitor 113, thus requiring significant switching capabilities and an increased number of transient stabilization capacitors 113, 114, 115.

[0051] Figure 2 An embodiment of a gain arrangement 200 is shown, comprising a reference Figure 1A and 1B The fixed gain arrangement described is equivalent to the fixed gain arrangement 101 . Figure 2 The variable gain arrangement 102 also includes an input capacitor arrangement 105, a feedback capacitor 108, an amplifier 111 and a first resistor 112, which are also similar to the reference Figure 1A and 1B For the sake of brevity, the components described will not be described here. Figure 1A 、 1B and 2 have common features.

[0052] For example, Figure 2 In some embodiments, the transient compensation capacitor arrangement of some embodiments may include a transient compensation capacitor 121, which is a current injection component 121 configured to inject a desired amount of charge onto the feedback capacitor 108. The current injection component may be, for example, Figure 2 1. In one embodiment, current injection capacitor 121 is coupled to a first voltage, such as a common-mode voltage, and is switchably coupled to feedback capacitor 108. Specifically, transient compensation capacitor 121 is switchably coupled to a first node of the feedback capacitor. After the gain of variable gain arrangement 102 is increased, current injection capacitor 121 is then configured to couple to feedback capacitor 108 so that the charge injected into feedback capacitor 108 induces an output voltage correction that minimizes transient stabilization effects. In one or more embodiments, current from 121 is injected into feedback capacitor 108 for a predetermined amount of time, where the predetermined amount of time is based on a change in the gain that variable gain arrangement 102 applies to the input signal to provide the output signal.

[0053] The variable gain arrangement may include a polarity switching arrangement. The polarity switching arrangement may be configured to provide switching of the polarity of the charge applied to the feedback capacitor 108. The polarity switching arrangement may include four switches disposed around the current injection capacitor, the switches being configured to provide a change in the polarity of the charge provided by the current injection capacitor 121. However, in other embodiments, where the variable gain arrangement 102 is configured to compensate for a gain change from high to low, such four switches may not be necessary, and instead, only two switches may be used to switchably connect the current injection capacitor between a first voltage, such as a common mode voltage, and the current injection capacitor 121.

[0054] The variable gain arrangement 102 may further include a sample and hold arrangement 122. The sample and hold arrangement 112 may be arranged in parallel with the feedback capacitor 108 and may have an output coupled to a current injection capacitor 121. The sample and hold arrangement 122 may be configured to provide the required charge to the current injection capacitor 121. The sample and hold arrangement 122 may allow the current injection capacitor 121 to effectively track the output voltage. The sample and hold arrangement 122 is provided herein as an example; however, it will be appreciated that any suitable circuitry that allows the current injection capacitor 121 to be appropriately charged to provide current injection suitable for compensating for transient effects may be utilized. The sample and hold arrangement 122 may be used to sample a signal condition (e.g., the voltage of the output signal) just before a gain change is made. The sample and hold arrangement 122 may be configured to use the sampled signal condition to restore the signal condition after the gain switch by providing an injection from the current injection capacitor 121 onto the feedback capacitor 108.

[0055] In more detail, Figure 2 The embodiment depicted in provides charge replenishment for the feedback capacitor. Figure 1A and 1BAs described, gain switching is achieved by varying the coupled input capacitor while keeping the feedback capacitor fixed. As previously discussed, other methods can be used to adjust the ratio of the capacitances of the input and feedback capacitors. In this example, changing the capacitance of the coupled input capacitor from 6pF to 1.5pF reduces the gain of the second stage by a factor of four. A fourfold gain reduction requires the output voltage to suddenly become four times smaller. The charge conservation of the feedback capacitor will resist the abrupt step. By injecting a defined amount of charge (positive or negative), the voltage across the feedback capacitor can be corrected to the desired amplitude value essentially instantly. The correction is almost instantaneous because the time required to replenish the charge can be much shorter than the settling time of the variable gain arrangement, effectively eliminating the need for stabilization. The correction charge can be derived from the voltage across the feedback capacitor, which can be captured using a sample-and-hold circuit arrangement at time t1, just before the change in amplifier gain is initiated by the change in the coupled input capacitor. The correction charge is then derived from the sampled voltage, amplified by + or -1 (depending on the direction of the gain change), and derived from the current injection capacitor that converts the voltage into charge. A correction charge, defined by the product of the sampled voltage on the feedback capacitor, the sign of the injection capacitor, and the capacitance, is injected into the amplifier input at time t2. Time t2 occurs immediately after sampling instant t1. In the example of the correction charge required when stepping down the gain by a factor of 4, the charge correction is -0.75 times the capacitance of the feedback capacitor. In the example of the correction charge required when stepping up the gain by a factor of 4, the charge correction is +3 times the capacitance of the feedback capacitor. It should be noted that charge needs to be taken out of the feedback capacitor when reducing the gain, while charge needs to be added when increasing the gain. In one or more embodiments, input capacitors that are not coupled to coupled input capacitors can be precharged by keeping them connected to a first voltage (e.g., a common-mode voltage).

[0056] Figure 3 An embodiment of a gain arrangement 300 is shown, comprising a reference Figure 1A and 1B The fixed-gain arrangement described is equivalent to the fixed-gain arrangement. Figure 2 The variable gain arrangement 102 also includes an input capacitor arrangement 105, a feedback capacitor 108, an amplifier 111 and a first resistor 112, which are also similar to the reference Figure 1A and 1B For the sake of brevity, the components described will not be described here. Figure 1A 、 1B and 3.

[0057] Figure 3The embodiment of FIG. 3 shows an example gain arrangement 300 in which the transient compensation capacitor arrangement 313 includes both a first current injection capacitor 321 and a second current injection capacitor 322. The first injection current capacitor 322 is configured to inject current into the feedback capacitor 108 immediately after it is connected to the feedback capacitor. Similarly, the second injection current capacitor 321 is configured to inject a current having an opposite polarity into the capacitor 108 immediately after it is connected to the feedback capacitor 108. By providing first and second current injection capacitors, the circuit can compensate for both gain changes from low to high and gain changes from high to low.

[0058] Figure 3 An example of a polarity reversal arrangement is shown that includes four switches that reverse the polarity of the charge provided from the second current injection capacitor 321 to the feedback capacitor 108. The second current injection capacitor 322 does not need to reverse its polarity, and therefore, two switches are sufficient to selectively couple the second current injection capacitor 322 to the feedback capacitor 108. It will be appreciated that in other embodiments, a different number of switches may be suitable for providing selective coupling of either or both of the first current injection capacitor 321 and the second current injection capacitor 322 to the feedback capacitor 108.

[0059] Figure 4 An example radar system 400 is shown, comprising a transmitter path 401 configured to transmit a plurality of radar signals. The radar system 400 further comprises a receiver path 402 configured to receive a plurality of reflected radar signals, wherein the receiver path 402 comprises a plurality of radar signals as described in reference to FIG. Figure 1A 、 1B , 2, and 3. Radar system 400 may be any suitable radar system 400 in which transient stabilization effects caused by sudden gain changes on the receiver path may be undesirable. For example, radar system 400 may be an automotive radar system.

[0060] Figure 5 Shown including reference Figure 4 An example of a vehicle 500 is described with respect to a radar system 501. Figure 5 A car 500 is depicted, but it should be understood that the vehicle can be any motor vehicle that can benefit from an installed radar system 501. For example, the vehicle 500 can be a car, a van, a truck, a bus, a construction vehicle, or any other vehicle that can share the road with other vehicles traveling on it. The radar system 501 can also be used in vehicles 500 that do not use roads but may have other obstacles that need to be navigated, such as a boat or ship.

[0061] Unless a particular order is explicitly stated, the instructions and / or flowchart steps in the above figures may be performed in any order. Furthermore, those skilled in the art will recognize that although one example instruction set / method has been discussed, the materials in this specification may be combined in various ways to produce other examples and should be understood within the context provided in this detailed description.

[0062] In some example embodiments, the instruction sets / method steps described above are implemented as functions and software instructions embodied as executable instruction sets that are implemented on a computer or a machine programmed and controlled by the executable instructions. Such instructions are loaded for execution on a processor (e.g., one or more CPUs). The term processor includes a microprocessor, a microcontroller, a processor module or subsystem (including one or more microprocessors or microcontrollers), or other control or computing devices. A processor may refer to a single component or a plurality of components.

[0063] In other examples, the instruction sets / methods described herein and the data and instructions associated therewith are stored in corresponding storage devices, which are implemented as one or more non-transient machine or computer-readable or computer-usable storage media. Such computer-readable or computer-usable storage media are considered part of an article (or product). An article or product may refer to any manufactured single component or multiple components. Non-transient machine or computer-usable media as defined herein does not include signals, but such media may be capable of receiving and processing information from signals and / or other transient media.

[0064] Example embodiments of the materials discussed in this specification may be implemented, in whole or in part, via network, computer, or data-based devices and / or services. These may include the cloud, the Internet, an intranet, a mobile device, a desktop computer, a processor, a lookup table, a microcontroller, a consumer device, infrastructure, or other enabling devices and services. As may be used herein and in the claims, the following non-exclusive definitions are provided.

[0065] In one example, one or more instructions or steps discussed herein are automated. The term automation or automatically (and similar variations thereof) means the use of computers and / or mechanical / electrical devices to control the operation of a device, system, and / or process without the need for human intervention, observation, effort, and / or decision-making.

[0066] It should be understood that any components that are said to be coupled can be coupled or connected directly or indirectly. In the case of indirect coupling, additional components can be placed between the two components that are said to be coupled.

[0067] In this specification, example embodiments have been presented in terms of a selected set of details. However, one skilled in the art will appreciate that many other example embodiments can be practiced that include different selected sets of these details. It is intended that the appended claims cover all possible example embodiments.

Claims

1. A variable gain arrangement for a receiver path, characterized in that The receiver path is configured to receive an input signal and apply a gain to the input signal to provide an output signal, the variable gain arrangement comprising: an input capacitor arrangement through which the input signal is transmitted, the input capacitor arrangement comprising a first input capacitor; a feedback capacitor arranged in series with the input capacitor arrangement, wherein the gain applied by the variable gain arrangement is based on a ratio of capacitances of the first input capacitor and the feedback capacitor, and a gain switching device configured to provide adjustment of the gain applied to the input signal by changing the capacitance of the feedback capacitor and the ratio of the input capacitor arrangement; an amplifier arranged in series with the input capacitor arrangement, wherein the amplifier is additionally arranged in parallel with the feedback capacitor, and wherein the amplifier is configured to provide the output signal; and a transient compensation capacitor arrangement comprising at least a first transient compensation capacitor, wherein after the gain of the variable gain arrangement is changed, at least one transient compensation capacitor is configured to be coupled to or decoupled from the feedback capacitor such that transient stabilization effects caused by the gain change are compensated.

2. The variable gain arrangement according to claim 1, characterized in that The input capacitor arrangement is the gain switching device, and wherein the input capacitor arrangement further comprises: a second input capacitor arranged in parallel with the first input capacitor; and a coupled input capacitor, wherein the coupled input capacitor is a capacitor through which the input signal is transmitted, wherein the first input capacitor and the second input capacitor are switchably arranged such that functionality of the coupled input capacitor is switchably provided by one of the first input capacitor and the second input capacitor.

3. The variable gain arrangement according to claim 1, characterized in that The transient compensation capacitor arrangement comprises a plurality of transient compensation capacitors, wherein, following the gain change imposed by the variable gain arrangement, interconnections of the plurality of capacitors of the transient compensation capacitor arrangement and the feedback capacitor are dynamically reconfigured to provide compensation for the transient stabilization effects.

4. The variable gain arrangement according to claim 1, characterized in that The first transient compensation capacitor is a current injection capacitor switchably coupled to the feedback capacitor, wherein the current injection capacitor is configured to be coupled to the feedback capacitor after a gain change of the output signal so that charge is injected into the feedback capacitor, wherein the charge injection provides for compensation for the transient stabilization effect.

5. A variable gain arrangement according to any one of claims 2 to 4, characterised in that The first input capacitor and the second input capacitor have different capacitances, such that switching between the first input capacitor and the second input capacitor to define the coupled input capacitor causes the change in the gain applied by the variable gain arrangement.

6. The variable gain arrangement according to claim 5, characterized in that The input capacitor arrangement comprises: a first input path including the first input capacitor; and a second input path comprising the second input capacitor, wherein the first input path is arranged in parallel with the second input path, and wherein the first input path and the second input path are switchably coupleable between: the amplifier; and First voltage.

7. A variable gain arrangement according to any one of claims 4 to 6, characterised in that The current injection capacitor is a first current injection capacitor coupled to a first node of the feedback capacitor, and wherein the transient compensation capacitor arrangement comprises a second current injection capacitor coupled to a second node of the feedback capacitor, wherein the second current injection capacitor is switchably coupleable to the feedback capacitor, wherein: responsive to an increase in the gain of the variable gain arrangement, the feedback capacitor being configured to couple to the feedback capacitor; and In response to a decrease in the gain of the variable gain arrangement, the second feedback capacitor is configured to be coupled to the feedback capacitor.

8. A gain arrangement of a receiver path, characterized in that The gain arrangement comprises a variable gain arrangement according to any one of claims 1 to 6, wherein the input signal received by the variable gain arrangement is a variable gain input signal and the output signal provided by the variable gain arrangement is a variable gain output signal, wherein the gain arrangement further comprises a fixed gain arrangement configured to receive a fixed gain input signal and to apply a fixed gain to the fixed gain input signal to provide a fixed gain output signal, wherein the fixed gain arrangement is arranged in series with the variable gain arrangement, the fixed gain arrangement comprising: a third input capacitor through which the fixed gain input signal is transmitted; a second feedback capacitor arranged in series with the third input capacitor, wherein the gain applied by the fixed gain arrangement is based on a ratio of capacitances of the second feedback capacitor and the third input capacitor; A second amplifier is arranged in series with the third input capacitor, wherein the second amplifier is additionally arranged in parallel with the second feedback capacitor, and wherein the second amplifier is configured to provide the fixed gain output signal.

9. A radar system, characterized in that: include: a transmitter path configured to transmit a plurality of transmit radar signals; A receiver path configured to receive a plurality of reflected radar signals, wherein the receiver path comprises a gain arrangement according to claim 8.

10. A motor vehicle, characterized in that: The motor vehicle comprises a radar system according to claim 9 .

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