A DEVICE AND A METHOD FOR PROCESSING A RECEIVING SIGNAL AND A MIXING UNIT

Abstract

A device (100, 200, 300) for processing a received signal, with the following features: a receiving device (110) designed to receive a received signal (112), wherein the received signal (112) has at least one signal component with a first frequency; a mixer unit (130) designed to combine the received signal (112) and a compensation signal (142) using at least one active element to obtain a compensated received signal, and designed to generate a mixer output signal (132) based on the compensated received signal and a local oscillator signal (122), wherein the mixer output signal (132) has a signal component corresponding to at least one signal component of the received signal (112) with a second frequency, the first frequency being higher than the second frequency, and wherein the mixer unit (130) has a first mixer to mix the compensated received signal with the local oscillator signal (122) to generate the mixer output signal (132); and a compensation unit (140) designed to generate the compensation signal (142) based on an analysis of the mixer output signal (132), so that interference components contained in the mixer output signal (132) can be reduced based on the compensation signal (142); a phase shifter (350) designed to provide the local oscillator signal (322) to the mixer unit (330) at successive time intervals with different phase shifts, such that the mixer output signal (332) has successive time parts with different phase shifts, wherein the compensation unit (340) is designed to generate the compensation signal (342) based on at least two parts of the mixer output signal (332) with different phase shifts.

Description

[0001] Embodiments relate to concepts for frequency conversion of electrical signals and in particular to an apparatus and a method for processing a received signal and a mixer unit.

[0002] In communications technology, the frequency conversion of electrical signals is performed, for example, by mixers. For example, in receivers, down-conversion involves converting a high-frequency wanted signal to a low-frequency intermediate frequency or base frequency using an oscillator signal. During down-conversion, unwanted frequency components are often generated by interference signals already present in the received signal or by interference components generated by the mixing itself.

[0003] For example, homodyne receivers are problematic when an interference signal is present at the antenna or RF (radio frequency) input at (approximately) the same frequency as the local oscillator (LO) signal, which can lead to unwanted DC output signals. This can reduce the receiver's performance due to the resulting asymmetry in the circuitry. Furthermore, further processing of the signal affected by DC interference can often be difficult.

[0004] For example, in most radar systems, transmission and reception occur at the same time and at the same frequency. As a result, sensor self-interference is a major problem. The circuit block most affected is usually the receive mixer, as this is often the most sensitive component in the signal path. It is often necessary to process very small wanted signals together with strong interferers, primarily caused by self-interference. For example, very linear mixers can be used to prevent performance degradation in the presence of self-interference. This typically results in high power consumption and noise.

[0005] US patent application US 2009 / 0154595 A1 proposes techniques for deriving bias voltages to minimize a measured residual sideband in a received or transmitted signal or to optimize other parameters of the received or transmitted signal. For example, a control voltage is combined with a local oscillator signal and applied to the gates of a plurality of transistors that mix an input signal.

[0006] US 6711396 B1 describes a method for reducing local oscillator or carrier leakage in frequency conversion mixers. Bias voltages are used to generate compensation currents intended to compensate for different DC components at different nodes in a mixer.

[0007] Document US 2009 / 0323864 A1 discloses a receiver arrangement with a differential output mixer arrangement including a main mixer and a trim mixer, and a mixer feedback loop configured to receive differential output signals generated by the mixer arrangement. The mixer feedback loop generates a feedback signal based on the received differential output signals and provides the feedback signal to the mixer arrangement to reduce DC offset and second-order intermodulation.

[0008] US patent application US 2011 / 0188555 A1 discloses a device for controlling the generation of a DC signal at the output of a mixer such that the DC signal is predictable. Furthermore, German patent application DE 10 2012106101 A1 discloses concepts for generating test signals.

[0009] There is a need to create a concept for frequency conversion of received signals that makes it possible to reduce interference signal components and / or power consumption.

[0010] This need is met by a device for processing a received signal according to claim 1, a mixer unit according to claim 17 and a method for processing a received signal according to claim 18.

[0011] Some embodiments relate to a device for processing a received signal, comprising a receiving device, a mixer unit, and a compensation unit. The receiving device is designed to receive a received signal. The received signal has at least one signal component with a first frequency. Furthermore, the mixer unit is designed to combine the received signal and a compensation signal with the aid of at least one active element in order to obtain a compensated received signal. In addition, the mixer unit is designed to generate a mixer output signal based on the compensated received signal and a local oscillator signal. The mixer output signal has a signal component with a second frequency corresponding to the at least one signal component of the received signal. The first frequency is higher than the second frequency.Furthermore, the compensation unit is designed to generate the compensation signal based on an analysis of the mixer output signal, so that interference components contained in the mixer output signal can be reduced based on the compensation signal.

[0012] By implementing an additional input of the mixer unit for a compensation signal and coupling the received signal to the compensation signal via at least one active element directly in the mixer unit, the noise component in the mixer unit's output signal can be easily reduced based on an analysis of the mixer output signal. Furthermore, power consumption can be kept low.

[0013] In some embodiments, the compensation unit is designed to provide the compensation signal iteratively based on a repeated analysis of the mixer output signal. This can make it possible to significantly reduce the noise signal component over multiple iterations.

[0014] Some embodiments relate to a mixer unit having an input stage and a mixer stage. The input stage has a first transconductance stage and a second transconductance stage. The first transconductance stage is configured to convert a received voltage signal into a first current signal, and the second transconductance stage is configured to convert a compensation voltage signal into a second current signal. Furthermore, the input stage is configured to sum the first current signal and the second current signal to obtain a summed current signal. The mixer stage is configured to mix the summed current signal with a local oscillator signal to obtain a mixer output signal.

[0015] Exemplary embodiments are explained in more detail below with reference to the accompanying figures. They show: Fig. 1 is a block diagram of a device for processing a received signal; Fig. 2 shows a block diagram of another device for processing a received signal; Fig. 3 is a block diagram of another device for processing a received signal; Fig. 4 a circuit diagram of a mixer unit; Fig. 5 is a block diagram of a mixer unit; Fig. 6 a flowchart of a method for processing a received signal.

[0016] In the following description of the accompanying figures, which show exemplary embodiments, identical reference numerals designate identical or comparable components. Furthermore, collective reference numerals are used for components and objects that appear multiple times in an exemplary embodiment or in a drawing, but are described together with respect to one or more features. Components or objects described with identical or collective reference numerals may be identical with respect to individual, several, or all features, for example, their dimensions, but may also be different, unless the description explicitly or implicitly indicates otherwise.

[0017] Fig. 1 shows a block diagram of a device 100 for processing a received signal 112 according to one embodiment. The device 100 comprises a receiving device 110, an optional local oscillator unit 120, a mixer unit 130, and a compensation unit 140. The receiving device 110 is connected by an output to an input of the mixer unit 130, the local oscillator unit 120 is connected by an output to an input of the mixer unit 130, the compensation unit 140 is connected by an output to an input of the mixer unit 130, and the mixer unit 130 is connected by an output to an input of the compensation unit 140. The receiving device 110 can receive a received signal 112. This received signal has at least one signal component with a first frequency. The local oscillator unit 120 may provide a local oscillator signal 122 having a local oscillator frequency.Furthermore, the mixer unit 130 can combine the received signal 112 and a compensation signal 142 with the aid of (or based on) at least one active element to obtain a compensated received signal. In addition, the mixer unit 130 can generate a mixer output signal 132 based on the compensated received signal and the local oscillator signal 122. The mixer output signal has a signal component corresponding to the at least one signal component of the received signal and having a second frequency. The first frequency is higher than the second frequency. Furthermore, the compensation unit 140 can generate the compensation signal 142 based on an analysis of the mixer output signal 132, so that interference components contained in the mixer output signal 132 can be reduced based on the compensation signal 142.

[0018] The active element allows the received signal 112 to be combined with the compensation signal 142 directly in the mixer unit with low or negligible losses. This allows the reduction of noise components in the mixer output signal 142 with minimal effort and / or low power consumption.

[0019] The receiving device 110 can be an input interface of the device 100 or the mixer unit 130, for example, to receive a received signal 112 from a transmitter via a wired connection. Alternatively, the receiving device 110 can also be designed to wirelessly receive a received signal from a transmitter. For this purpose, the receiving device 110 can, for example, have an antenna, one or more filters, and / or one or more amplifiers to receive the received signal and optionally preprocess it. Optionally or additionally, the receiving device 110 can also be designed as a transmitting and receiving device in order to be able to both transmit signals and receive the received signal 112.

[0020] The received signal 112 can be any signal that has signal components whose frequency is to be converted to a lower frequency. For this purpose, the received signal 112 can have useful signal components in one or more frequency bands or with one or more frequencies. At least one of these signal components has a frequency that, after processing by the mixer unit 130, comes to be at the second frequency in the mixer output signal 132. For example, the received signal 112 can have a maximum or predefined signal amplitude or a maximum or predefined signal power at the first frequency, or the first frequency can correspond to a predefined frequency that is to be converted to the second frequency (e.g., predefined intermediate frequency or baseband frequency) for further processing of the received signal.

[0021] The optional local oscillator unit 120 may be an external unit or part of the device 100 and may be implemented in different ways. For example, the local oscillator unit 120 may include a crystal oscillator, a voltage-controlled oscillator, or another source that provides a mixing signal to the mixing unit to generate the local oscillator signal 122.

[0022] The local oscillator signal 120 can essentially be a signal at the local oscillator frequency or can have frequency components in different frequency bands or at one or more different frequencies. The local oscillator signal 122 is often provided with exactly one frequency with a very small tolerance (e.g., <1%, <0.1%, or <0.01% of the local oscillator frequency). Optionally, the local oscillator signal 120 can also be frequency-modulated, or the local oscillator frequency can be changed according to a predefined frequency ramp (e.g., in radar applications). Thus, the local oscillator signal 120 can also be provided with a controllably variable signal frequency.

[0023] The mixer unit 130 combines (e.g., adds, sums, or subtracts) the received signal 112 and the compensation signal 142 with the aid of (or using) at least one active element. In contrast to passive elements, an active element is, for example, an electrical component capable of amplifying a voltage, current, or power of a signal. For example, the active element can be a transistor (e.g., bipolar transistor, field-effect transistor, metal-oxide-semiconductor transistor) or another electrical component with corresponding functionality. In contrast, passive elements (e.g., directional couplers) cannot enable such amplification on their own. Thus, the device 100 does not, for example, use a directional coupler to combine the received signal 112 and the compensation signal 142. (Exactly) one active element (e.g., a transistor) may be sufficient to combine the two signals.However, more than one active element can be used to combine the two signals (e.g. at least two transistors in a differential design).

[0024] Furthermore, the mixer unit 130 generates a mixer output signal 132 based on the compensated received signal and the local oscillator signal 122, such that the mixer output signal 132 has signal components corresponding to the received signal 112 with a lower frequency than in the received signal 112. In other words, the mixer unit 130 can mix the compensated received signal with the local oscillator signal 122, so that, among other things, signal components are generated that correspond to signal components of the received signal 112 and have a lower frequency. For example, useful signal components of the compensated received signal can be converted from a high-frequency range to an intermediate frequency range, baseband frequency range, or low-frequency range. The mixer unit 130 may, for example, comprise a mixer to mix the compensated received signal with the local oscillator signal 122 to generate the mixer output signal 132.

[0025] Compensation unit 140 can generate compensation signal 142 based on an analysis of mixer output signal 132. An analysis of mixer output signal 132 can be performed in different ways. For example, a temporal and / or frequency-selective analysis of signal components can be performed to determine the type and extent of interference signal components. Alternatively, a characteristic value can be determined that indicates information about an absolute or relative magnitude of the interference signal components in a predetermined frequency range and / or a predetermined time interval.

[0026] Based on this analysis, the compensation unit 140 can generate the compensation signal 142 such that the mixer output signal 132 subsequently contains fewer interference components or components of interference signals (e.g., noise or non-linear signal components). For example, the compensation unit 140 can repeatedly perform an analysis of the mixer output signal 132 (e.g., determining a characteristic value or temporal and / or frequency-selective analysis of the mixer output signal) and repeatedly change the compensation signal 142 such that interference signals or interference signal components can be or are reduced in at least one frequency range (e.g., DC component or low-frequency range). In other words, the compensation unit 140 can provide the compensation signal 142 iteratively based on a repeated analysis of the mixer output signal 132. This allows the noise component in the mixer output signal 132 to be reduced over several iterations.

[0027] Alternatively, the compensation unit 140 can also generate an optimal or very good compensation signal 142 directly from the analysis of the mixer output signal 132 without having to perform multiple iterations. This allows a noise component in the mixer output signal 132 to be reduced significantly more quickly, but this may require greater computational effort or hardware complexity for the compensation unit 140. The compensation unit 140 can generate the compensation signal 142, for example, such that the compensation signal 142, when combined with the received signal 112, cancels out at least a portion of the interference signals from the received signal 112 (e.g., by destructive interference) at least in one frequency range.

[0028] Fig. Figure 2 shows a further device 200 for processing a received signal 212 according to an embodiment. The structure of the device 200 essentially corresponds to that shown in Fig. 1, so that the above statements also apply accordingly to the device 200. In this example, the receiving device 210 has an antenna to wirelessly receive a received signal 212 (e.g., a strong signal (interference) at the local oscillator frequency). Furthermore, the local oscillator 220 provides a local oscillator signal LO 222 for downconversion of the received signal RF1 221. The compensation unit 240 is designed to find a compensation signal RF2 242 that minimizes or reduces the DC output signal at the output of the mixer unit 230. The mixer unit 230 can then provide a mixer output signal IF 232 with a minimized or reduced DC output signal.

[0029] According to the Fig. In the example shown in Figure 2, for example, a homodyne receiver with blocker suppression (interference signal suppression) can be implemented.

[0030] The mixer unit 130 can generate the mixer output signal 132 continuously at the same phase position of the local oscillator signal 122. However, a minimal DC voltage signal is often present at the mixer output even when interference signals and the local oscillator signal 122 are 90° out of phase with each other. This can be undesirable, however, because despite an (almost) zeroed output signal, a high output signal can then be present at the mixer input (received signal), which cannot be eliminated or reduced by the control system, or can only be eliminated with difficulty. Therefore, in some applications or devices, the phase position of the local oscillator signal 122 can be switchably selected, for example, to select between 0° and 90° local oscillator phase. The control system can, for example, reduce or minimize the square sum of the two resulting DC voltage signals for 0° and 90° phase positions of the local oscillator signal 122.

[0031] In other words, the device 100, 200 may optionally, alternatively or additionally to one or more of the aforementioned aspects comprise a phase shifter 350, as described for the device 300 in Fig. 3 as an exemplary embodiment. The phase shifter 350 is arranged between the local oscillator unit 320 and the mixer unit 330 and can provide the local oscillator signal 322 to the mixer unit 330 at successive intervals with different phase shifts, so that the mixer output signal 332 has successive portions with different phase shifts. The compensation unit 340 can then generate the compensation signal 342 based on at least two portions of the mixer output signal 332 with different phase shifts of the local oscillator signal 322.

[0032] The timing of the phase shift of the local oscillator signal 322 by the phase shifter 350 can be controlled by an external control unit, by a control unit of the local oscillator 320 or by a control unit of the compensation unit 340 (as in the example of Fig. 3) can occur repeatedly at equal time intervals, random time intervals, or at predetermined time intervals. In other words, the compensation unit 340 can, for example, generate a control signal 348 for the phase shifter 350, so that a temporal sequence of different phase shifts can be controlled by the control signal 348. This can additionally ensure that the compensation unit 340 knows when parts of the mixer output signal 332 are present with which phase shift for the analysis of the mixer output signal 332.

[0033] The respective phase shift between two consecutive intervals can have any desired value. For example, the phase shift can alternate between +90° and -90° (e.g., alternating between 0° and 90° phase positions). Alternatively, the phase can always be shifted by +90° (or -90°). The time intervals in which the mixer output signal 332 is generated with a specific phase position of the local oscillator signal 322 before the phase of the local oscillator signal 322 is shifted again can be of any desired length. For example, the frequency at which the phase shift is performed is significantly smaller than the frequency of the local oscillator signal 322. For example, the phase shift can be performed at a frequency that is less than 1 / 1000 (or less than 1 / 5000, less than 1 / 10000, less than 1 / 50000 or less than 1 / 100000) of the local oscillator frequency.For example, in radar applications, a local oscillator signal with a frequency between 50 GHz and 100 GHz (e.g., 77 GHz) can be used, and the phase shift can be applied at a frequency between 100 Hz and 1 MHz (or between 1 kHz and 10 kHz). Conversely, the local oscillator signal 322 is applied without phase shift for a time interval of 1 µs to 10 ms (or from 100 µs to 1 ms).

[0034] As an alternative to a phase shifter 350, the mixer unit 330 can, for example, comprise a second mixer that can generate a second mixer output signal based on the received signal 212, a phase-shifted local oscillator signal, and the compensation signal 342. The second mixer output signal also comprises a signal component with the second frequency corresponding to the at least one signal component of the received signal 212. The compensation unit 340 can then generate the compensation signal 342 based on the first and second mixer output signals, as shown for the example in Fig. 3. For example, the second mixer may also first combine the received signal 212 with the compensation signal 342 using at least one active element and generate the second mixer output signal based on the compensated received signal and the local oscillator signal 322. Alternatively, the second mixer may use the compensated received signal that the first mixer also uses to generate the first mixer output signal.

[0035] By implementing a second mixer, the analysis of the mixer output signal can be faster because the two phase-shifted output signals are present simultaneously, but this may increase the hardware effort.

[0036] As already mentioned, the analysis of the mixer output signal can be performed in a variety of ways. For example, when analyzing the mixer output signal 332 (or the two mixer output signals of the two mixers), the compensation unit 340 can calculate a magnitude of a complex number that has a real part calculated based on a first phase shift of the local oscillator signal of the mixer output signal 322 (or one of the two mixer output signals) and an imaginary part calculated based on a second phase shift of the local oscillator signal 322 of the mixer output signal 332 (or the other of the two mixer output signals).

[0037] Furthermore, the compensation unit 340 can calculate a magnitude of the complex number (and optionally also a phase of the complex number). The compensation unit 340 can then generate the compensation signal 342, for example, such that the magnitude of the complex number can be reduced.

[0038] In other words, the evaluation of the residual noise component (in the mixer output signal) can be carried out, for example, via the mixer output signal IF output of the mixer (or mixer unit) in combination with a phase-switchable local oscillator signal 322. The evaluation and control unit (e.g. part of the compensation unit) in Fig. 3 can establish two phase states at 0° and 90° relative phase of the local oscillator signal 322 and generate the mixer output signal IF 332 as a composite complex signal: VIF,complex=VIF,LOPhase0°+jVIF,LOPhase90°

[0039] For example, a complex mixing process can be represented using time-division multiplexing. This allows the magnitude and / or phase of the remaining interference signal component to be determined, which can be used to determine the compensation signal 342.

[0040] For example, V IF,LOPhase0° a DC offset at 0°, V IF,LOPhase90° a DC offset at 90° phase position and V IF,complex a complex number. The magnitude and / or phase of this complex number can be calculated. The compensation signal 342 can be generated to minimize or reduce the magnitude.

[0041] In other words, the real part of the complex number can correspond to or be based on a DC component of the mixer output signal 332 at the first phase shift of the local oscillator signal 322, and the imaginary part can correspond to or be based on a DC component of the mixer output signal 332 at the second phase shift of the local oscillator signal 322. The first or second phase shift can also be 0°, as long as the first and second phase shifts are different.

[0042] This compensation signal 342 can be fed to the second RF input RF2 (input for the compensation signal) of the mixer (or mixer unit) and added there to the first RF input RF1 (receive signal) before the mixing process. If the magnitude of the compensation signal 342 at RF2 is selected to be (essentially) equal to that of the interference signal at the RF1 input, and the phase is inverted, i.e., set 180° relative to the interference signal, a desired cancellation effect can be achieved.

[0043] The compensation signal 342 can be generated by the compensation unit 340 in different ways. For example, the mixer output signal 332 can be modified and fed back to the mixer unit 330 as the compensation signal 342.

[0044] Optionally, alternatively, or in addition to one of the aforementioned aspects, the compensation unit 340 can generate the compensation signal 342 based on a local oscillator signal 322 (of the local oscillator unit) modified as a function of the analysis of the mixer output signal 332. The local oscillator signal 322 can, for example, be modified in its magnitude and phase (e.g., by amplitude and / or phase modulation) such that the interference signal components in the mixer output signal 332 are reduced.

[0045] Such a modification can be carried out in different ways. For example, an in-phase quadrature phase modulator 344 can be used, as in the example of Fig. 3. In other words, the compensation unit 340 may include an in-phase quadrature phase modulator 344 that modifies the local oscillator signal 322 based on the analysis of the mixer output signal 332 to obtain the compensation signal 342.

[0046] In this way, a compensation signal 342 can be obtained in a simple manner, which can reduce the noise components of the mixer output signal 332.

[0047] In other words, as an actuator for the compensation signal 342 (as in Fig. 3) an IQ modulator may be used which can modify a portion of the local oscillator signal 322 in magnitude and / or phase according to the signals at its in-phase input I and quadrature-phase input Q.

[0048] As already described, the compensation signal 342 can be generated iteratively. For example, in a first iteration, the magnitude and phase of the local oscillator signal can be set to 0 using the in-phase and quadrature-phase signals. In a second iteration, the magnitude can be set to 0.5 and the phase to 0, or vice versa. The subsequent iterations can be performed depending on the influence of the mixer output signal 332.

[0049] The analysis of the mixer output signal 332 as well as the provision of the control signal 348 for the phase shifter 350 and the in-phase and quadrature phase signals for the in-phase quadrature phase modulator 344 can be carried out and provided, for example, by an evaluation and control unit 346 of the compensation unit 340, as in the example of Fig. 3. The device 300 can, for example, implement active interference signal suppression with an evaluation and control unit.

[0050] For example, despite an interference signal at the RF input at the LO frequency, a minimized or reduced interference signal at DC (direct voltage) can be achieved.

[0051] In addition, the device 300 is subject to Fig. 1 and Fig. 2 as well as their embodiments and the general concept already made previously. Accordingly, one or more in connection with Fig. 3 mentioned aspects can be combined with one of the previous embodiments or the general concept.

[0052] The receiving device, the local oscillator unit, the mixer unit, the compensation unit, and / or the phase shifter may be stand-alone hardware units or part of a process, microcontroller, or digital signal processor, as well as part of a computer program or a software product for execution on a processor, microcontroller, or digital signal processor. The various units may be implemented independently of one another or at least partially together.

[0053] The mixer unit can be implemented in different ways. For example, an adder for combining the received signal and the compensation signal can be placed upstream of a mixer. Alternatively, the combiner can be integrated into the mixer.

[0054] For example, the mixer unit may comprise a mixer or mixer stage, a first transconductance stage, and a second transconductance stage. The first transconductance stage may then convert the received signal, which is present as a voltage signal, into a first current signal, and the second transconductance stage may convert the compensation signal, which is also present as a voltage signal, into a second current signal. The mixer unit may then sum the first current signal and the second current signal to obtain a summed current signal. Furthermore, the mixer may mix the summed current signal with the local oscillator signal to obtain the mixer output signal.

[0055] A voltage signal, for example, is a signal that is fed by a voltage source and cannot, for example, be easily summed with another voltage signal. A current signal, on the other hand, is a signal that is fed by a current source and can, for example, easily be summed with another current signal.

[0056] Optionally, each of the two transconductance stages can have a current source that can be switched via a transistor as an active element to generate the corresponding current signal when the received signal or the compensation signal is applied to a control terminal of the transistor.

[0057] Furthermore, the mixer unit can optionally have a differential structure.

[0058] An example of such a mixer unit 400 is shown in Fig. 4. The first transconductance stage 410 has a current source I1, a first transistor T5, and a second transistor T6. The current source I1 is connected to an emitter terminal (source terminal) of the first transistor T6 and to an emitter terminal of the second transistor T6. Furthermore, the current source I1 is connected to a reference potential (e.g., ground). The first transistor T6 of the first transconductance stage 410 has its collector terminal (drain terminal) connected to a first input of the mixer or mixer stage 430, and the second transistor T6 of the first transconductance stage 410 has its collector terminal connected to a second input of the mixer stage 430. A first differential signal of the received signal RF1 is applied to the base terminal (control electrode) of the first transistor T5, and a second differential signal of the received signal is applied to the base terminal of the second transistor T6.The second transconductance stage 420 also includes a current source I2, a first transistor T7 (active element), and a second transistor T8 (active element). The current source I2, in turn, has one output connected to a reference potential (e.g., ground) and a second output connected to the emitter terminal of the first transistor T7 and the emitter terminal of the second transistor T8 of the second transconductance stage 420. The first transistor T7 of the second transconductance stage 420 is connected to the first input of the mixer stage 430, and the collector terminal of the second transistor T8 of the second transconductance stage 420 is connected to the second input of the mixer stage 430.A first differential signal of the compensation signal RF2 is applied to a base terminal of the first transistor T7 of the second transconductance stage 420, and a second differential signal of the compensation signal RF2 is applied to a base terminal of the second transistor T8 of the second transconductance stage 420. Consequently, the currents through the first transistor T5 of the first transconductance stage 410 and the first transistor T7 of the second transconductance stage 420 can add up at the input of the mixer stage 430. Accordingly, the currents through the second transistor T6 of the first transconductance stage 410 and the second transistor T8 of the second transconductance stage 420 can add up at the second input of the mixer stage 430. The mixer stage 430 includes first to fourth transistors T1, T2, T3, T4, and a first and second load resistor R. Land a direct current (DC) voltage source. The first transistor T1 and the second transistor T2 of the mixer stage 430 are each connected by their emitter terminals to the first input of the mixer stage 430, and the third transistor T3 and the fourth transistor T4 of the mixer stage 430 are connected by their respective emitter terminals to the second input of the mixer stage 430. The collector terminal of the first transistor T1 and the third transistor T3 of the mixer stage 430 are connected to the DC voltage source via the first resistor RL, and the collector terminal of the second transistor T2 and the fourth transistor T4 of the mixer stage 430 are connected to the DC voltage source via the second resistor R Lconnected to the DC voltage source DC. A first differential signal of the local oscillator signal LO is applied to a base terminal of the second transistor T2 and the third transistor T3 of the mixer stage 430, and a second differential signal of the local oscillator signal LO is applied to a base terminal of the first transistor T1 and the fourth transistor T4 of the mixer stage 430. The mixer output signal IF can then be provided between the collector terminal of the first transistor T1 and the collector terminal of the fourth transistor T4 of the mixer stage 430. The mixer unit 400 thus has inputs for a differential receive signal RF1, a differential compensation signal RF2, and a differential local oscillator signal LO, as well as an output for a differential mixer output signal IF.

[0059] In other words, Fig. Figure 4 shows an example of an active receive mixer, as can be used in integrated circuits. The RF1 signal (receive signal) can be converted from voltage to current in the input transistors T5, T6 (transconductance stage). Transistors T1, T2, T3, and T4, which can be controlled by the local oscillator signal LO, can perform the actual mixing function by switching the current signal from the input stage with alternating polarity to the two load resistors RL, where the current signal can be converted back to voltage.

[0060] For example, with transistors T7 and T8, the input stage consisting of transistors T5 and T6 can be placed a second time, in parallel with the first stage. This is possible at this point due to the conversion of RF input voltage to a current signal. Two high-impedance current sources are connected in parallel, and the total current is fed to the mixer transistors T1, T2, T3, and T4. This allows for the realization of a mixer (receiver mixer) with three inputs.

[0061] Fig. 5 shows a block diagram of a mixer unit 500 as one embodiment. The mixer unit 500 includes an input stage 510 and a mixer stage 520. The input stage 510 has a first transconductance stage 512 and a second transconductance stage 514. The first transconductance stage 512 can convert a received voltage signal 502 into a first current signal, and the second transconductance stage 514 can convert a compensation voltage signal 504 into a second current signal. Furthermore, the input stage 510 can sum the first current signal and the second current signal to obtain a summed current signal 516. The mixer stage 520 can mix the summed current signal 516 with a local oscillator signal 506 to obtain a mixer output signal 522.

[0062] In this way, a mixer unit with at least 3 inputs can be realized with little effort and / or low power consumption, which can actively take into account a compensation voltage signal 504 via transconductance stages before mixing a received voltage signal 502 (up or down mixing) in order to reduce noise signal components in the mixer output signal 522.

[0063] Optionally, additionally or alternatively, the mixer unit 500 may implement one or more further aspects corresponding to one or more of the aspects previously described in connection with the general concept or one of the embodiments in particular Fig. 4, described.

[0064] Some embodiments relate to the suppression of interference signals, an active loss suppressor, or a homodyne receiver with a compensation signal injected at a third mixer input. The described concept aims to reduce or even eliminate any performance degradation of a receive mixer. In addition, the mixer design itself can be simplified, as a reduction in the dynamic range can be enabled.

[0065] In a proposed active loss suppressor (device according to one of the embodiments), a compensation signal can be fed into a mixer. This compensation signal can be an additional radio-frequency (RF) signal that is added to the wanted signal. The phase and amplitude of the compensation signal can be selected such that, for example, self-interfering signal components can be optimally or significantly suppressed. Destructive interference of the self-interfering signal with the compensation signal can be achieved.

[0066] One aspect is the injection of an additional high-frequency signal with a variable amplitude and phase directly into the mixer core via an additional high-frequency input (RF input).

[0067] Optionally (for example in Fig. 2) the actual RF input signal (receive signal) is fed to the receive mixer via an amplifier to optimize or improve the overall noise figure. Additionally, a RF modulator output signal (compensation signal) can be coupled into the mixer via a second RF input of the receive mixer. The RF modulator can be a unit that can set the amplitude and phase of its output signal to any ratio with respect to its input. The RF modulator can, for example, be connected to a common or ordinary local oscillator input or derive the output signal from another RF signal source in the system (e.g., from the transmit path, if present).

[0068] The detailed implementation of the proposed additional mixer input depends on the actual circuit architecture. For example, this can be implemented using switches in the current domain, and thus the additional input can be implemented as an additional current input that can be added to the signal current.

[0069] One possible implementation is a mixer or mixer unit with three inputs and a control loop for suppressing interference signals. To provide an additional control variable for suppressing interference signals at the mixer's radio frequency (RF) input, a mixer with an additional, third input can be introduced. This makes it possible to add two radio frequency (RF) signals before converting them to the intermediate frequency (or low frequency) range, which can be used, for example, to eliminate or reduce unwanted signals in the high-frequency part of the circuit.

[0070] This compensation signal can reduce or completely eliminate the impairment of the mixer function mentioned in the presence of such interference signals.

[0071] For example, in Fig. Figure 2 shows a device for implementing a homodyne receiver. In addition to the mixer with an additional radio-frequency (RF) signal input RF2, a control unit can also be used to control the generation of the compensation signal. The compensation signal can be derived from an additional radio-frequency (RF) signal source and its magnitude and phase can be adjusted such that the sum of the interference on RF1 (the received signal) and the compensation signal on RF2 (almost) exactly cancel each other out.

[0072] The unwanted output signal of the mixer, which is to be reduced or minimized by the control, can serve as the input signal for the control of the compensation signal.

[0073] In one implementation, the compensation signal can be generated from the local oscillator signal LO of the mixer or device and only the magnitude and phase can be adjusted via a suitable actuator, such as an IQ modulator.

[0074] Some embodiments relate to a homodyne receiver having a device according to the described concept or one of the embodiments.

[0075] In some embodiments, a radar system is implemented with a transmitting unit and a device according to the described concept or one of the embodiments (e.g., a radar system for a vehicle). The transmitting unit can transmit a transmitted signal at the local oscillator frequency (e.g., frequency-modulated or with a frequency ramp), and the receiving device can receive a reflection of the transmitted signal from an object as the received signal.

[0076] Fig.6 shows a flowchart of a method 600 for processing a received signal as one embodiment. The method 600 comprises receiving 610 a received signal and providing 620 a local oscillator signal. The received signal has at least one signal component with a first frequency. Furthermore, the method 600 comprises combining 630 the received signal and a compensation signal with the aid of at least one active element in order to obtain a combined input signal. In addition, a mixer output signal is generated 640 based on the compensated received signal and the local oscillator signal. The mixer output signal has a signal component with a second frequency corresponding to the at least one signal component of the received signal. The first frequency is higher than the second frequency.Furthermore, the method 600 comprises generating 650 the compensation signal based on an analysis of the mixer output signal, so that interference components contained in the mixer output signal can be reduced based on the compensation signal.

[0077] The method 600 may include one or more further steps corresponding to one or more of the aspects previously described in connection with the concept or one of the embodiments.

[0078] The features disclosed in the above description, the following claims and the attached figures can be important and implemented both individually and in any combination for the realization of an embodiment in its various forms.

[0079] Although some aspects have been described in connection with a device, it is understood that these aspects also represent a description of the corresponding method, so that a block or component of a device can also be understood as a corresponding method step or as a feature of a method step. Similarly, aspects described in connection with or as a method step also represent a description of a corresponding block, detail, or feature of a corresponding device.

[0080] Depending on specific implementation requirements, embodiments of the invention may be implemented in hardware or software. The implementation may be performed using a digital storage medium, such as a floppy disk, a DVD, a Blu-ray disc, a CD, a ROM, a PROM, an EPROM, an EEPROM, or a FLASH memory, a hard disk, or other magnetic or optical storage device storing electronically readable control signals that can interact or interact with a programmable hardware component to perform the respective method.

[0081] A programmable hardware component can be formed by a processor, a computer processor (CPU = Central Processing Unit), a graphics processor (GPU = Graphics Processing Unit), a computer, a computer system, an application-specific integrated circuit (ASIC = Application-Specific Integrated Circuit), an integrated circuit (IC = Integrated Circuit), a single-chip system (SOC = System on Chip), a programmable logic element or a field-programmable gate array with a microprocessor (FPGA = Field Programmable Gate Array).

[0082] The digital storage medium can therefore be machine- or computer-readable. Some embodiments thus comprise a data carrier having electronically readable control signals capable of interacting with a programmable computer system or a programmable hardware component such that one of the methods described herein is performed. One embodiment is thus a data carrier (or a digital storage medium or a computer-readable medium) on which the program for performing one of the methods described herein is recorded.

[0083] In general, embodiments of the present invention can be implemented as a program, firmware, computer program, or computer program product with program code or data, wherein the program code or data is effective to perform one of the methods when the program runs on a processor or a programmable hardware component. The program code or data can also be stored, for example, on a machine-readable medium or data carrier. The program code or data can be present, among other things, as source code, machine code, or bytecode, as well as other intermediate code.

[0084] A further embodiment is a data stream, a signal sequence, or a sequence of signals that represents the program for performing one of the methods described herein. The data stream, the signal sequence, or the sequence of signals can be configured, for example, to be transferred via a data communication connection, for example, via the Internet or another network. Thus, embodiments also include signal sequences representing data that are suitable for transmission via a network or data communication connection, wherein the data represents the program.

[0085] A program according to one embodiment can implement one of the methods during its execution, for example, by reading memory locations or writing one or more pieces of data into them, which may trigger switching operations or other processes in transistor structures, amplifier structures, or other electrical, optical, magnetic, or other functionally principle-based components. Accordingly, by reading a memory location, data, values, sensor values, or other information can be acquired, determined, or measured by a program. A program can therefore acquire, determine, or measure quantities, values, measured quantities, and other information by reading one or more memory locations, and can trigger, initiate, or perform an action and control other devices, machines, and components by writing to one or more memory locations.

[0086] The above-described embodiments are merely illustrative of the principles of the present invention. It is understood that modifications and variations of the arrangements and details described herein will be apparent to others skilled in the art. Therefore, it is intended that the invention be limited only by the scope of the following claims and not by the specific details presented in the description and explanation of the embodiments herein.

Claims

[1] A device (100,200,300) for processing a received signal, having the following features: a receiving device (110) designed to receive a received signal (112), wherein the received signal (112) has at least one signal component with a first frequency; a mixer unit (130) configured to combine the received signal (112) and a compensation signal (142) with the aid of at least one active element to obtain a compensated received signal, and configured to generate a mixer output signal (132) based on the compensated received signal and a local oscillator signal (122), wherein the mixer output signal (132) has a signal component corresponding to the at least one signal component of the received signal (112) with a second frequency, wherein the first frequency is higher than the second frequency, wherein the mixer unit (130) has a first mixer for mixing the compensated received signal with the local oscillator signal (122) to generate the mixer output signal (132); and a compensation unit (140) designed to generate the compensation signal (142) based on an analysis of the mixer output signal (132), so that interference components contained in the mixer output signal (132) can be reduced based on the compensation signal (142); a phase shifter (350) configured to provide the local oscillator signal (322) at temporally successive intervals to the mixer unit (330) with different phase shifts, such that the mixer output signal (332) has temporally successive parts with different phase shifts, wherein the compensation unit (340) is configured to generate the compensation signal (342) based on at least two parts of the mixer output signal (332) with different phase shifts. [2] The device of claim 1, wherein the at least one active element is a transistor. [3] Device according to claim 1, wherein the compensation unit (340) is designed to generate a control signal (348) for the phase shifter (350) such that a temporal sequence of different phase shifts can be controlled by the control signal (348). [4] Device according to one of claims 1 to 3, wherein the phase shift is alternately +90° and -90°. [5] Device according to one of claims 1 to 4, wherein the phase shift occurs at a frequency which is less than one thousandth of a local oscillator frequency of the local oscillator signal. [6] Device according to one of claims 1 to 5, wherein the mixer unit (130) comprises a second mixer which is designed to generate a second mixer output signal based on the received signal, a local oscillator signal which is phase-shifted with respect to the local oscillator signal (122) used by the first mixer and the compensation signal (142), wherein the second mixer output signal has a signal component corresponding to the at least one signal component of the received signal and having the second frequency, wherein the compensation unit (140) is designed to generate the compensation signal (142) based on the first and the second mixer output signal. [7] Device according to one of claims 1 to 6, wherein the compensation unit (140) is designed to calculate a magnitude of a complex number when analyzing the mixer output signal (132), the complex number having a real part based on a first phase shift of the local oscillator signal (122) and an imaginary part based on a second phase shift of the local oscillator signal (122), the compensation unit (140) being designed to generate the compensation signal (142) such that the magnitude of the complex number is reducible. [8] Apparatus according to claim 7 when dependent on any one of claims 1 to 4, wherein the real part is based on a DC component of the mixer output signal (132) at the first phase shift of the local oscillator signal (122) and the imaginary part is based on a DC component of the mixer output signal (132) at the second phase shift of the local oscillator signal (122). [9] Apparatus according to any one of the preceding claims, wherein the compensation unit (140) is configured to provide the compensation signal (142) iteratively based on a repeated analysis of the mixer output signal (132). [10] Device according to one of the preceding claims, wherein the compensation unit (140) is designed to generate the compensation signal (142) based on a local oscillator signal modified in dependence on the analysis of the mixer output signal (132). [11] The apparatus of claim 10, wherein the compensation unit (140) comprises an in-phase quadrature phase modulator configured to modify the local oscillator signal (122) based on the analysis of the mixer output signal to obtain the compensation signal (142). [12] Device according to one of the preceding claims, wherein the received signal and the compensation signal are voltage signals, wherein the mixer unit (400) comprises a mixer (430), a first transconductance stage (410) and a second transconductance stage (420), wherein the first transconductance stage (410) is designed to convert the received signal into a first current signal, wherein the second transconductance stage (420) is designed to convert the compensation signal into a second current signal, wherein the mixer unit (400) is designed to sum the first current signal and the second current signal to obtain a summed current signal, wherein the mixer (430) is designed to mix the summed current signal with the local oscillator signal to obtain the mixer output signal. [13] Device according to claim 12, wherein each of the two transconductance stages (410,420) comprises a current source which is designed to be switchable via a transistor for generating the corresponding current signal when the received signal or the combination signal is applied to a control terminal of the transistor. [14] Device according to claim 12 or 13, wherein the mixer unit (400) has a differential structure. [15] Homodyne receiver comprising a device according to any one of the preceding claims. [16] Radar system comprising a transmitting unit and a device according to one of claims 1 to 14, wherein the transmitting unit is designed to transmit a transmitting signal having a local oscillator frequency of the local oscillator signal, wherein the receiving device is designed to receive a reflection of the transmitting signal at an object as the receiving signal. [17] A mixer unit (400,500) with the following features, an input stage (510) having a first transconductance stage (410,512) and a second transconductance stage (420,514), wherein the first transconductance stage (410,512) is designed to convert a received voltage signal (502) into a first current signal, wherein the second transconductance stage (420,514) is designed to convert a compensation voltage signal (504) into a second current signal, wherein the input stage (510) is designed to sum the first current signal and the second current signal to obtain a summed current signal (516); a mixer stage (430,520) configured to mix the summed current signal (516) with a local oscillator signal (506) to obtain a mixer output signal (522); a phase shifter (350) configured to provide the local oscillator signal (506) at temporally successive intervals to the mixer stage (430, 520) with different phase shifts, so that the mixer output signal (522) has temporally successive parts with different phase shifts; and a compensation unit (340) configured to generate the compensation signal (504) based on at least two parts of the mixer output signal (522) with different phase shifts. [18] A method (600) for processing a received signal, comprising the following steps: Receiving (610) a received signal, wherein the received signal has at least a signal component with a first frequency; Providing (620) a local oscillator signal at successive intervals with different phase shifts; Combining (630) the received signal and a compensation signal using at least one active element to obtain a compensated received signal; Generating (640) a mixer output signal based on mixing the compensated received signal with the local oscillator signal, wherein the mixer output signal has a signal component corresponding to the at least one signal component of the received signal with a second frequency, wherein the first frequency is higher than the second frequency, and wherein the mixer output signal has temporally successive parts with different phase shifts due to the local oscillator signal; and Generating (650) the compensation signal based on an analysis of the mixer output signal, such that interference components contained in the mixer output signal can be reduced based on the compensation signal, and based on at least two parts of the mixer output signal with different phase shifts.

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