Voltage controlled oscillator and method of using the same

Abstract

Embodiments of the present disclosure generally relate to voltage controlled oscillators and methods of using the same. A voltage controlled oscillator (VCO) includes a pair of inductors coupled in series, a first pair of varactor diodes coupled in series, and a second pair of varactor diodes coupled in series. A first common mode node is between respective varactor diodes of the first pair of varactor diodes, and a second common mode node is between respective varactor diodes of the second pair of varactor diodes. A supply voltage node, which is a node between the pair of inductors, is switchably coupled to the first common mode node through a first switch. A control voltage node (V C ) is switchably coupled to the second common mode node through a second switch.

Description

Technical Field

[0001] This disclosure generally relates to electronic circuits, and in certain embodiments to voltage-controlled oscillators (VCOs). Background Technology

[0002] Advanced driver assistance systems (ADAS) are typically used in automotive applications to prevent accidents or reduce the severity of accidents resulting from collisions with stationary or moving objects. ADAS applications include adaptive cruise control, pre-collision safety systems, blind spot detection, lane change assist, and more. ADAS may include short-range radar (SRR) and long-range radar (LRR) sensors deployed around the vehicle to detect objects near the vehicle.

[0003] The radar system measures the emitted signal (T) by the radar system. x The signal and the corresponding receiver reflected by the target (R) x The time delay between echo signals is used to sense the target's distance and velocity. Long-range radar sensors can operate in long-range radar bands (e.g., 76 GHz to 77 GHz) and cover distances up to several hundred meters with low-power RX signals. Transceiver radars capable of covering both short-range and long-range radar bands are desirable to reduce the cost and design effort of advanced driver assistance systems. Summary of the Invention

[0004] According to an embodiment, a voltage-controlled oscillator (VCO) circuit includes: a pair of inductors coupled in series; a first pair of varactor diodes coupled in series, with a first common-mode node between corresponding varactor diodes of the first pair; a second pair of varactor diodes coupled in series, with a second common-mode node between corresponding varactor diodes of the second pair, a first terminal of the first pair of varactor diodes coupled to a first terminal of the second pair of varactor diodes and a first terminal of the inductor pair, and a second terminal of the first pair of varactor diodes coupled to a second terminal of the second pair of varactor diodes and a second terminal of the inductor pair; a power supply voltage node switchably coupled to the first common-mode node via a first switch, the power supply voltage node being a node located between the pair of inductors; and a control voltage node switchably coupled to the second common-mode node via a second switch (V0). C ).

[0005] According to another embodiment, the voltage-controlled oscillator (VCO) circuit 100 includes: a resonant circuit including a first pair of varactor diodes and a second pair of varactor diodes, the resonant frequency of the resonant circuit depending on the first capacitance of the first pair of varactor diodes and the second capacitance of the second pair of varactor diodes, the resonant frequency setting the output frequency of the VCO circuit; an oscillator core coupled to the resonant circuit; and a switching circuit configured to operate the VCO circuit in a first operating mode and a second operating mode, the switching circuit being configured to select the first pair of varactor diodes for tuning the resonant frequency in a first frequency band in the first operating mode, and the switching circuit being configured to select the second pair of varactor diodes for tuning the resonant frequency in a second frequency band outside the first frequency band in the second operating mode.

[0006] According to another embodiment, a method of operating a voltage-controlled oscillator (VCO) circuit includes: operating the VCO in a first operating mode using a switching circuit, the VCO circuit including a resonant circuit including a first pair of varactor diodes, a second pair of varactor diodes, and a resonant frequency for setting the output frequency of the VCO; the switching circuit setting the first pair of varactor diodes in the first operating mode to tune the resonant frequency in a first frequency band; and operating the VCO in a second operating mode using the switching circuit, the switching circuit setting the second pair of varactor diodes in the second operating mode to tune the resonant frequency in a second frequency band outside the first frequency band.

[0007] It should be understood that the foregoing general description and the following detailed description are exemplary and illustrative only, and not intended to limit the scope of this disclosure. Attached Figure Description

[0008] To gain a more complete understanding of this disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings.

[0009] Figure 1 This is an example of a voltage-controlled oscillator;

[0010] Figure 2 This is a schematic diagram of the voltage-controlled oscillator in the embodiment;

[0011] Figure 3 This is a schematic diagram of the voltage-controlled oscillator in the embodiment;

[0012] Figure 4 This is a schematic diagram of the voltage-controlled oscillator in the embodiment;

[0013] Figure 5 This is a schematic diagram of the voltage-controlled oscillator in the embodiment;

[0014] Figure 6 This is a schematic diagram of the voltage-controlled oscillator in the embodiment;

[0015] Figure 7 This is a schematic diagram of the voltage-controlled oscillator in the embodiment;

[0016] Figure 8 This is a diagram illustrating an embodiment of a dual-band voltage-controlled oscillator with a frequency determined by a control voltage;

[0017] Figure 9 This is a block diagram of the processing system in the embodiment;

[0018] Figure 10 This is a flowchart of an embodiment method for operating a voltage-controlled oscillator;

[0019] Figure 11 This is a flowchart of an embodiment method for operating a voltage-controlled oscillator;

[0020] Figure 12 This is a flowchart of an embodiment method for operating a voltage-controlled oscillator; and

[0021] Figure 13 This is a flowchart of an embodiment method for operating a voltage-controlled oscillator.

[0022] Unless otherwise indicated, corresponding numbers and symbols in the different figures generally refer to corresponding parts. The figures are drawn to clearly illustrate relevant aspects of the embodiments and are not necessarily drawn to scale. The edges of features drawn in the figures do not necessarily indicate the end of the feature's extent. Detailed Implementation

[0023] The manufacture and use of various embodiments are discussed in detail below. However, it should be understood that the various embodiments described herein are applicable to a wide range of specific contexts. The specific embodiments discussed are merely illustrative of particular ways of making and using the various embodiments and should not be construed as limiting the scope.

[0024] References to "embodiment" or "one embodiment" within the framework of this specification are intended to indicate that a particular configuration, structure, or feature described with respect to that embodiment is included in at least one embodiment. Therefore, phrases such as "in an embodiment" or "in one embodiment" that may appear at one or more points in this specification do not necessarily refer to the same embodiment. Furthermore, in one or more embodiments, specific constructions, structures, or features may be combined in any suitable manner.

[0025] Although aspects of the invention have been described primarily in the context of voltage-controlled oscillators operating within advanced driver assistance systems in automotive applications, these aspects can be similarly applied to other systems, other applications, and across different frequency ranges.

[0026] References used herein are provided for convenience only and therefore do not limit the extent of protection or the scope of embodiments. It is desirable to be able to generate reference signals for radar transmitters and receivers (e.g., automotive radar systems) that can cover both short-range and long-range radar bands to reduce cost and design effort.

[0027] Embodiments of this disclosure provide a solution to the aforementioned problems by using a switching circuit comprising a switch placed at the common-mode node of a varactor diode to enable dual-band VCO operation across, for example, short-range and long-range radar bands. Using a dual-band scheme allows a single VCO to cover a wider tuning range (e.g., 5 GHz) across both the short-range and long-range radar bands without increasing phase noise. Advantageously, because the switch is located between the common-mode node and the voltage connection and not along the signal path of the LC energy storage circuit, this configuration does not affect the phase noise or parasitic capacitance of the LC energy storage circuit. By using a single pair of varactor diodes to cover each frequency sub-band, the VCO's frequency is related to the voltage gain (k... VCO The Q-factor can be reduced from 5 / 4 (e.g., for short-range radar bands) to 5 (e.g., for long-range radar bands), which can reduce phase noise. The Q-factor of the LC energy storage circuit can be increased, and parasitic capacitance can be reduced by using a switching circuit with a switch connected to a common-mode node of a varactor diode. This avoids the trade-off between the LC slot Q-factor and tuning range required in prior art VCO designs. Furthermore, the disclosed embodiments can be implemented compactly to reduce silicon area footprint because the same LC energy storage circuit inductor and oscillator core are used for both short-range and long-range radar bands.

[0028] According to one or more embodiments of this disclosure, a voltage-controlled oscillator (VCO) circuit may include a switching circuit having a switch positioned at the common-mode node of a varactor diode to enable dual-band operation. This allows a single VCO circuit to cover a wider range of frequencies (e.g., for short-range and long-range radar bands). The switch is positioned along the connection of the common-mode node with voltage and not along the signal path of the LC energy storage circuit. This allows configuration to switch between short-range and long-range radar modes without adding unwanted phase noise or parasitic capacitance. The Q factor of the LC energy storage circuit can be increased, and the parasitic capacitance can be reduced with the disclosed switching circuit connection, thereby reducing power consumption. Because the same LC energy storage circuit inductor and oscillator core are used for both short-range and long-range radar bands, the disclosed embodiments can be implemented compactly to reduce silicon footprint.

[0029] Typically, radar systems use local oscillators, such as voltage-controlled oscillators (VCOs), to generate reference signals for the radar transmitter and receiver. A VCO is an oscillator circuit that generates an AC signal with a frequency that depends on the control voltage. A wide frequency tuning range (TR), such as approximately 5 GHz, is advantageous for covering both short-range and long-range radar bands (e.g., from 76 GHz to 81 GHz). However, radar sensitivity is limited by phase noise (PN), which may be more critical for long-range radar applications due to the lower power of the RX signal. This is because of the high k-value of large-area varactor diodes, for example, used in short-range radar applications. VCO Achieving both wide frequency range (TR) and low frequency range (PN) for a VCO is challenging.

[0030] Figure 1 An example voltage-controlled oscillator (VCO) 10 is shown. VCO 10 includes an LC energy storage circuit 20. VCO 10 may also include an oscillator core 2. Oscillator core 2 includes a cross-coupled transistor 4, a cross-coupled transistor 6, and a current source 8. Current source 8 provides bias current to the cross-coupled transistors 4 and 6 (e.g., CMOS or bipolar junction transistors). VCO 10 is a differential circuit that provides a differential output voltage.

[0031] The LC energy storage circuit 20 includes inductors 12 and 14, varactor diode 22, and varactor diode 24 coupled in parallel. In some examples, each of varactor diode 22 and varactor diode 24 may be a variable capacitor, etc.

[0032] Power supply voltage V DD A terminal is coupled to the power supply voltage node 16 between inductors 12 and 14. Varactor diodes 22 and 24 have variable capacitance, which can be controlled by a control voltage V. C A node is connected to common-mode node 26 for adjustment to tune the output frequency of VCO10 within the tuning range. Although the LC energy storage circuit 20 is shown as a single-supply voltage circuit with the oscillator core 2 connected to the reference node, the LC energy storage circuit 20 can also be a dual-supply voltage circuit, with the oscillator core 2 connected to, for example, a negative supply voltage -V. DD The node, not the reference node.

[0033] During the operation of the LC energy storage circuit 20, the charge oscillates back and forth between inductors 12 and 14, and resonates at a resonant frequency f between varactor diodes 22 and 24. VCO Oscillation. The resonant frequency f of the LC energy storage circuit 20. VCO Given by equation (1):

[0034]

[0035] Where L is the sum of the inductances of inductor 12 and inductor 14, and C(V C ) is used as the control voltage V C The total capacitance of varactor diodes 22 and 24 is a function of the capacitance of the varactor diodes 22 and 24. The LC energy storage circuit 20 has a parallel parasitic resistance R representing the resistive losses of inductors 12 and 14, varactor diodes 22 and 24. P To maintain oscillation, the cross-coupled transistors 4 and 6 of the oscillator core 2 provide a parallel parasitic resistance R greater than that of the LC energy storage circuit 20. P negative resistance -1 / G m As shown in equation (2):

[0036]

[0037] Among them, -G m It is the transconductance of cross-coupled transistor 4 and cross-coupled transistor 6. Thus, oscillator core 2 drives LC energy storage circuit 20 in response to the parallel parasitic resistance R. P The continuous oscillation on the resistive loss.

[0038] A wide frequency tuning range (TR) for the VCO is desired to cover both short-range and long-range radar bands, such as from 76 GHz to 81 GHz, while reducing design and manufacturing costs. In some embodiments, the VCO's wide frequency tuning range (TR) is in the range of a smaller frequency (e.g., 38 GHz to 40.5 GHz), which is then increased to the 76 GHz to 81 GHz range by a frequency multiplier. However, the large-area varactor diode with sufficient variable capacitance to achieve a wide frequency TR results in high k-values. VCO This results in increased unwanted phase noise.

[0039] In the various embodiments described in this application, multiple overlapping tuned subbands can be employed to achieve the desired wide-frequency TR, wherein each subband is covered by a pair of varactor diodes. Using this method, the frequency of the VCO is related to the voltage gain (kΩ). VCO This can reduce the factor by 5 / 4 (e.g., for short-range radar bands) to 5 (for long-range radar bands), which can reduce phase noise.

[0040] Figure 2A dual-band VCO 100 according to some embodiments is shown. The dual-band VCO 100 may include a dual-band LC energy storage circuit 120 and a switching circuit 150. The dual-band VCO 100 may also include an oscillator core 2. In an embodiment, the dual-band LC energy storage circuit 120 is a single resonant circuit that operates in a first operating mode to generate a resonant frequency tunable across a long-range radar band and in a second operating mode to generate a resonant frequency tunable across a short-range radar band.

[0041] The dual-band LC energy storage circuit 120 includes a first inductor 112, a second inductor 114, and a pair of first varactor diodes C. VA and a pair of second varactor diodes C VB In some embodiments, the dual-band LC energy storage circuit 120 is a single-ended circuit, wherein the oscillator core 2 is connected to a reference node. In various embodiments, the varactor diode can be replaced by a variable capacitor or the like. In embodiments, a minimum varactor diode size is used for each frequency sub-band.

[0042] In some embodiments, the dual-band LC energy storage circuit 120 is a dual-supply voltage circuit, wherein the oscillator core 2 is connected to, for example, a negative power supply voltage -V. DD Nodes instead Figure 2 The reference node is shown. The first inductor 112 and the second inductor 114 are coupled in series with the oscillator core 2.

[0043] Oscillator core 2 provides a parallel parasitic resistance R greater than that of the dual-band LC energy storage circuit 120. P negative resistance -1 / G m As a non-limiting example, oscillator core 2 is included. Any suitable oscillator core can be used and is within the scope of the disclosed embodiments.

[0044] Each of the pair of first varactor diodes 122 and 124, the pair of second varactor diodes 132 and 134, and the pair of inductors 112 and 114 is coupled in parallel to the oscillator core 2. Therefore, the first terminal of the pair of first varactor diodes 122 and 124 is coupled to the first terminal of the pair of second varactor diodes 132 and 134, and the second terminal of the pair of first varactor diodes 122 and 124 is coupled to the second terminal of the pair of second varactor diodes 132 and 134.

[0045] The first common-mode node 126 is located between the first varactor diode 122 and the first varactor diode 124. The second common-mode node 136 is located between the second varactor diode 132 and the second varactor diode 134.

[0046] Switching circuit 150 includes a first switch 152, a second switch 154, a third switch 156, and a fourth switch 158. The various switches of switching circuit 150 allow the dual-band VCO 100 to operate in a long-range radar band mode (see below). Figure 3 ) or short-range radar band mode (see below) Figure 4 )operate.

[0047] Because the same inductors (e.g., first inductor 112 and second inductor 114) and oscillator core 2 from the same single circuit are used for both the first operating mode in the long-range radar band and the second operating mode in the short-range radar band, the dual-band VCO 100 can be compactly implemented to reduce the silicon area footprint.

[0048] The first inductor 112 and the second inductor 114 are coupled in series with the oscillator core 2. A power supply voltage node 116 is arranged between inductors 112 and 114. Inductors 112 and 114 can be planar inductors with interconnecting materials (e.g., aluminum, copper, etc.) arranged in a spiral coil pattern, gyroscope, etc. However, any suitable inductor can be used. In some embodiments, a single inductor or more than two inductors are used. Power supply voltage V DD The terminal is coupled to the power supply voltage node 116.

[0049] When operating in the first operating mode (e.g., in a long-range radar band), a pair of first varactor diodes 122 and 124 can be used to control the resonant frequency f of the dual-band LC energy storage circuit 120. VCO .

[0050] The control voltage V connected to, for example, a phase-locked loop (PLL) C A node can be connected to a first common-mode node 126 to control the variable capacitance of the first varactor diodes 122 and 124. The capacitance of the first varactor diodes 122 and 124 can be selected to be as small as possible while still covering the long-range radar band to reduce LC tank losses and improve phase noise performance.

[0051] In some embodiments, such as for an operating frequency of approximately 40 GHz with an inductor value of 100 pH, the first varactor diode 122 and the first varactor diode 124 have a variable capacitance in the range of 30 fF to 40 fF over an input voltage range of 0 V to 1 V.

[0052] When operating in a second operating mode (e.g., in a short-range radar band), the pair of second varactor diodes 132 and 134 can be used to control the resonant frequency fVCO of the dual-band LC energy storage circuit 120.

[0053] The control voltage V connected to, for example, a phase-locked loop (PLL) C The node can be connected to the second common-mode node 136 to control the variable capacitance of the second varactor diode 132 and the second varactor diode 134. The capacitance of the second varactor diode 132 and the second varactor diode 134 can be selected to be as small as possible while still covering the short-range radar band to reduce LC tank loss and improve phase noise performance.

[0054] In some embodiments, such as for an operating frequency of approximately 40 GHz with an inductor value of 100 pH, the second varactor diode 132 and the second varactor diode 134 have a variable capacitance in the range of 120 fF to 160 fF over an input voltage range of 0 V to 1 V.

[0055] In this embodiment, the first varactor diode 122, the first varactor diode 124, the second varactor diode 132, and the second varactor diode 134 are accumulation mode MOS (AMOS) varactor diodes. However, it should be noted that any suitable type of voltage-controlled capacitor can be used.

[0056] The switching circuit 150 allows the dual-band VCO 100 to switch between a first operating mode and a second operating mode. In the first operating mode, the dual-band LC energy storage circuit 120 has a resonant frequency, for example, in a long-range radar band (e.g., in the range of 38 GHz to 38.5 GHz, which is subsequently increased to 76 GHz to 77 GHz by a frequency multiplier driven by the dual-band VCO 100). In the second operating mode, the dual-band LC energy storage circuit 120 has a resonant frequency, for example, in a short-range radar band (e.g., in the range of 38.5 GHz to 40.5 GHz, which is subsequently increased to 77 GHz to 81 GHz by a frequency multiplier driven by the dual-band VCO 100).

[0057] The first switch 152 is coupled to the first common-mode node 126 and the control voltage V. C Between nodes. The second switch 154 is coupled to the first common-mode node 126 and the power supply voltage V. DD Between terminals. The third switch 156 is coupled to the control voltage V at the second common-mode node 136. C Between nodes. The fourth switch 158 is coupled between the second common-mode node 136 and the reference node.

[0058] The first switch 152, the second switch 154, the third switch 156, and the fourth switch 158 can be any type of switch suitable for the circuit. In some embodiments, the first switch 152, the second switch 154, the third switch 156, and the fourth switch 158 are transistors that are turned on when the switch is open and turned off when the switch is closed. The switches open or close when a digital signal is applied as a bias voltage.

[0059] In various embodiments, the control terminals of the first switch 152, the second switch 154, the third switch 156, and the fourth switch 158 are coupled to the control terminals of a digital signal LR, which is configured to open and close the switches. The digital signal LR may be, for example, a static control bit used in automotive radar applications. In some embodiments, the digital signal LR may be coupled to the first switch 152 and the fourth switch 158 without inversion, such that they are closed when the digital signal LR is '0' (i.e., low) and open when the digital signal LR is '1' (i.e., high).

[0060] In some embodiments, the digital signal LR can be coupled to the second switch 154 via the first inverter 153 and to the third switch 156 via the second inverter 155, such that they are open when the digital signal LR is '0' (i.e., low) and closed when the digital signal LR is '1' (i.e., high).

[0061] The placement of the first inverter 153 relative to the second switch 154 and the second inverter 155 relative to the third switch 156 are included as non-limiting examples. In an embodiment, the digital signal LR is connected to the first switch 152 and the fourth switch 158 via corresponding inverters, such that they are open when the digital signal LR is '0' (i.e., low) and closed when the digital signal LR is '1' (i.e., high). In an embodiment, the digital signal LR may be coupled to the second switch 154 and the third switch 156 without inversion, such that they are closed when the digital signal LR is '0' (i.e., low) and open when the digital signal LR is '1' (i.e., high). Therefore, any suitable arrangement of the digital signal LR, inverters, and switches is included within the scope of the disclosed embodiments.

[0062] Because the first switch 152, the second switch 154, the third switch 156, and the fourth switch 158 are arranged between the connection of the first common-mode node 126 and the second common-mode node 136, which have a voltage or reference node, the switches do not follow the signal path of the dual-band LC energy storage circuit 120. Therefore, the differential oscillation signal of the dual-band LC energy storage circuit 120 does not pass through the first switch 152, the second switch 154, the third switch 156, and the fourth switch 158. Therefore, the first switch 152, the second switch 154, the third switch 156, or the fourth switch 158 does not affect the phase noise or parasitic capacitance of the dual-band LC energy storage circuit 120.

[0063] Figure 3 A dual-band VCO 100 in a first operating mode according to an embodiment is shown. In the first operating mode, first varactor diodes 122 and 124 control the resonant frequency f of the dual-band LC energy storage circuit 120.VCO Therefore, the dual-band VCO is tunable within, for example, the long-range radar band (e.g., in the range from 38 GHz to 38.5 GHz before being boosted by the frequency multiplier), using the first variable capacitor C. VA .

[0064] In the first operating mode, the digital signal LR is set to '1' (i.e., high), which closes the first switch 152 and the fourth switch 158. Signals to the second switch 154 and the third switch 156 are inverted by the first inverter 153 and the second inverter 155, respectively. Therefore, the high signal from the digital signal LR is converted to a low signal by the inverters, thereby opening the second switch 154 and the third switch 156. As a result, the voltage at the first common-mode node 126 is set to the control voltage V. C Furthermore, the voltage at the second common-mode node 136 is set to the voltage of the reference node (e.g., reference ground).

[0065] Closing the fourth switch 158 biases the second varactor diode 132 and the second varactor diode 134 to their maximum capacitance. In some embodiments where the second varactor diode 132 and the second varactor diode 134 are AMOS varactor diodes, closing the fourth switch 158 couples the second common-mode node 136 to the reference node, which is achieved by the power supply voltage V coupled to the power supply voltage node 116 at the reference node. DD The terminals are biased to set the second varactor diode 132 and the second varactor diode 134 to the maximum capacitance.

[0066] The second varactor diode 132 and the second varactor diode 134 are set to the maximum capacitance allow the pair of second varactor diodes C VB It is used as a fixed capacitor and provides a fixed contribution to the total capacitance of the dual-band LC energy storage circuit 120.

[0067] The closing of the first switch 152 sets the voltage at the first common-mode node 126 to the control voltage V. C This allows the capacitance of each of the first varactor diodes 122 and 124 to be adjusted by the control voltage V. C Tuning is performed. The total capacitance of the dual-band VCO 100 is therefore set to the maximum capacitance by the contributions from the first varactor diode 122 and the first varactor diode 124, as well as the fixed contributions from the second varactor diode 132 and the second varactor diode 134.

[0068] Therefore, in the first operating mode, the resonant frequency f VCO The control voltage V can be adjusted CTuning within, for example, a long-range radar band (e.g., 38 GHz to 38.5 GHz, subsequently increased to 76 GHz to 77 GHz by a frequency multiplier driven by a dual-band VCO 100), as follows: Figure 8 As shown in the diagram. First varactor diodes 122 and 124 are used to cover, for example, a long-range radar band. The frequency of the VCO is related to the voltage gain (kΩ). VCO This can be reduced by about 5 times (for long-range radar bands), which can reduce phase noise.

[0069] Figure 4 A dual-band VCO 100 in a second operating mode according to an embodiment is shown. In the second operating mode, a second varactor diode 132 and a second varactor diode 134 are used to control the resonant frequency fVCO of the dual-band LC energy storage circuit 120 to be tunable within, for example, a short-range radar band (e.g., across 2 GHz: from 38.5 GHz to 40.5 GHz, subsequently increased to 77 GHz to 81 GHz by a frequency multiplier driven by the dual-band VCO 100).

[0070] In the second operating mode, the digital signal LR is set to '0' (i.e., low), which disconnects the first switch 152 and the fourth switch 158. Signals to the second switch 154 and the third switch 156 are inverted by the first inverter 153 and the second inverter 155, respectively. Therefore, the low signal from the digital signal LR is converted to a high signal by the inverters, thereby closing the second switch 154 and the third switch 156. As a result, the voltage at the second common-mode node 136 is set to the control voltage V. C And the voltage at the first common-mode node 126 is set to the power supply voltage V. DD .

[0071] Closing the second switch 154 biases the first varactor diodes 122 and 124 to their minimum capacitances. In some embodiments where the first varactor diodes 122 and 124 are AMOS varactor diodes, closing the second switch 154 couples the first common-mode node 126 to the power supply voltage V. DD The terminals set the first varactor diode 122 and the first varactor diode 124 as the minimum capacitance.

[0072] Setting the first varactor diode 122 and the first varactor diode 124 to the minimum capacitance allows the pair of first varactor diodes C VA It is used as a fixed capacitor and provides a fixed contribution to the total capacitance of the dual-band LC energy storage circuit 120.

[0073] The closing of the third switch 156 sets the voltage at the second common-mode node 136 to the control voltage V. CThis allows the capacitance of each of the second varactor diode 132 and the second varactor diode 134 to be adjusted by the control voltage V. C The total capacitance of the dual-band VCO 100 is therefore a combination of the contributions from the tuning capacitance of the second varactor diode 132 and the second varactor diode 134, and a fixed contribution from the first varactor diode 122 and the first varactor diode 124, which are set to minimum capacitance.

[0074] Therefore, in the second operating mode, the resonant frequency fVCO can be adjusted by changing the control voltage V. C Tuning is performed, for example, in a short-range radar band (e.g., 38.5 GHz to 40.5 GHz, subsequently increased by a frequency multiplier to 77 GHz to 81 GHz), as follows: Figure 8 As shown in the diagram, using a second varactor diode 132 and a second varactor diode 134 to cover, for example, short-range radar bands, the kVCO of the dual-band LC energy storage circuit 120 is configured to improve phase noise performance.

[0075] Although a dual-band VCO has been used to describe it Figures 2-4 This is an example of an embodiment, but the architecture can be easily extended to a multi-band VCO. For example, a three-band VCO would include another pair of varactor diodes and a switch with appropriate logic circuitry to ensure operation of the multi-band VCO in a third operating state.

[0076] Figure 5 A dual-band VCO 200 according to some embodiments is shown. The dual-band VCO 200 includes a dual-band LC energy storage circuit 220 and a switching circuit 250. The dual-band VCO 200 may include an oscillator core 2.

[0077] The dual-band LC energy storage circuit 220 is a single resonant circuit operating in a first operating mode and a second operating mode. In the first operating mode, the dual-band VCO 200 operates at a resonant frequency, for example, in a long-range radar band. In the second operating mode, the dual-band VCO 200 operates across resonant frequencies, for example, in a short-range radar band.

[0078] The dual-band LC energy storage circuit 220 includes a first inductor 212, a second inductor 214, and a pair of first varactor diodes C. VA (First varactor diode 222 and first varactor diode 224), a pair of second varactor diodes C VB (Second varactor diode 232 and second varactor diode 234), first capacitor 242 and second capacitor 244.

[0079] The first inductor 212 and the second inductor 214 can be similar to those described above. Figure 2 , Figure 3 and Figure 4 The first inductor 112 and the second inductor 114 are described. However, any suitable inductor can be used. In some embodiments, a single inductor or more than two inductors are used.

[0080] The first varactor diode 222 and the first varactor diode 224 can be similar to those described above. Figure 2 The first varactor diode 122 and the first varactor diode 124 are described. The second varactor diode 232 and the second varactor diode 234 can be similar to those described above. Figure 2 The second varactor diode 132 and the second varactor diode 134 are described. However, any suitable type of voltage-controlled capacitor can be used instead of the various varactor diodes shown.

[0081] The first capacitor 242 and the second capacitor 244 can be any suitable type of capacitor. In some embodiments, such as for an operating frequency of approximately 40 GHz with an inductor value of 100 pH, the first capacitor 242 and the second capacitor 244 have capacitances in the range of 0 fF to 50 fF.

[0082] The first switch 252 is arranged between the second common-mode node 236 and the power supply voltage node 216. The second switch 254 is arranged between the first common-mode node 226 and the second common-mode node 236. The third switch 256 is arranged between the first capacitor 242 and the second capacitor 244.

[0083] The control terminals of the first switch 252, the second switch 254, and the third switch 256 are connected to the control terminals of the digital signal LR. By setting the digital value of the digital signal LR, the various switches are configured to operate in either the open or closed position.

[0084] The first switch 252, the second switch 254, and the third switch 256 can be any type of switch suitable for the circuit. In some embodiments, the first switch 252, the second switch 254, and the third switch 256 are transistors that are turned on when the switch is closed and turned off when the switch is open. The switches open or close when a digital voltage is applied as a bias voltage.

[0085] In one embodiment, the digital signal LR can be connected to the first switch 252 and the third switch 256 without inversion, such that they are closed when the digital signal LR is '0' (i.e., low) and open when the digital signal LR is '1' (i.e., high). The digital signal LR can be connected to the second switch 254 via an inverter 255, such that the second switch 254 is open when the digital signal LR is '0' and closed when the digital signal LR is '1'.

[0086] Similar to Figure 2 In the embodiments described, the arrangement of the inverters and switches is not limited. In one embodiment, the digital signal LR is connected to the first switch 252 and the third switch 256 via corresponding inverters, such that when the digital signal LR is '0' (i.e., low), the first switch 252 and the third switch 256 are open, and when the digital signal LR is '1' (i.e., high), the first switch 252 and the third switch 256 are closed. In another embodiment, the digital signal LR is connected to the second switch 254 without inversion, such that when the digital signal LR is '0' (i.e., low), the second switch 254 is closed, and when the digital signal LR is '1' (i.e., high), the first switch 252 and the third switch 256 are open.

[0087] Oscillator core 2 provides a parallel parasitic resistance R greater than that of the dual-band LC energy storage circuit 220. P negative resistance -1 / G m The first inductor 212 and the second inductor 214 are coupled in series with the oscillator core 2.

[0088] In various arrangements, the paired first varactor diode C VA The paired second varactor diode C VB The combination of the first capacitor 242 and the second capacitor 244, as well as the first inductor 212 and the second inductor 214, is coupled in parallel with the oscillator core 2.

[0089] The first common-mode node 226 is located between the first varactor diode 222 and the first varactor diode 224. The second common-mode node 236 is located between the second varactor diode 232 and the second varactor diode 234.

[0090] The switching circuit 250 includes a first switch 252, a second switch 254, and a third switch 256. The switching circuit enables the dual-band VCO 100 to operate in a first mode (see below). Figure 6 ) or second operating mode (see Figure 7 (The following operations are performed.)

[0091] Because the same inductors (e.g., first inductor 212 and second inductor 214) and oscillator core 2 (from the same single circuit) are used for both the first operating mode (i.e., across the long-range radar band) and the second operating mode (i.e., across the short-range radar band), the dual-band VCO 200 can be implemented compactly to reduce silicon area footprint.

[0092] The first inductor 212 and the second inductor 214 are coupled to the oscillator core 2. As shown in the figure, the power supply voltage node 216 is located between the first inductor 212 and the second inductor 214. The power supply voltage V... DD The terminal is coupled to power supply voltage node 216.

[0093] The switching circuit 250 allows the dual-band VCO 200 to switch between a first operating mode and a second operating mode.

[0094] As shown in the figure, the first switch 252 and the second switch 254 are respectively connected between the first common-mode node 226 and the second common-mode node 236. In this way, the differential oscillation signal of the dual-band LC energy storage circuit 220 is isolated, and the first switch 252 and the second switch 254 do not increase the phase noise or parasitic capacitance of the dual-band LC energy storage circuit 220.

[0095] Figure 6 An embodiment of the dual-band VCO 200 in a first operating mode is shown. In the first operating mode, the digital signal LR is set to '1'. In the first operating mode, the first switch 252 and the third switch 256 are in the closed position, and the second switch 254 is in the open position. The voltage at the first common-mode node 226 is set to the control voltage V. C The voltage at the second common node is set to the supply voltage V. DD When the third switch 256 is in the closed position, the capacitance of the first capacitor 242 and the second capacitor 244 contributes to the total capacitance of the dual-band LC energy storage circuit 220.

[0096] The pair of second varactor diodes C VB It is fixed, and is controlled by voltage V. C Adjustment to adjust the first varactor diode C VA The capacitor, the resonant frequency fVCO of the dual-band LC energy storage circuit 220 is tuned across, for example, the frequency band of a long-range radar.

[0097] Figure 7 An embodiment of the dual-band VCO 200 in a second operating mode is shown. In the second operating mode, the digital signal LR is set to '0'. In the second operating mode, the first switch 252 and the third switch 256 are in the open position, and the second switch 254 is in the closed position. The voltage at the first common-mode node 226 and the voltage at the second common-mode node 236 are set to the control voltage V. C When the third switch 256 is in the open position, the capacitance of the first capacitor 242 and the second capacitor 244 is excluded from the dual-band LC energy storage circuit 220.

[0098] via control voltage V C Adjustment to adjust a pair of second varactor diodes C VB and a pair of first varactor diodes C VA The capacitor, the resonant frequency fVCO of the dual-band LC energy storage circuit 220 is tuned across, for example, the short-range radar band.

[0099] In some embodiments, the dual-band VCO 100 or dual-band VCO 200 is implemented on one or more semiconductor chips. The semiconductor chip may be, for example, a fully depleted silicon-on-insulator (FD-SOI) complementary metal-oxide-semiconductor (CMOS) chip. The dual-band VCO 100 or dual-band VCO 200 may be integrated as a 38 GHz VCO connected to a frequency multiplier (e.g., a corresponding 77 GHz power amplifier (PA)). However, the dual-band VCO 100 or dual-band VCO 200 may be implemented using any suitable circuitry and integrated on any suitable chip, die, or device.

[0100] Although a dual-band VCO has been used to describe it Figures 5-7 This is one embodiment, but the architecture can be easily extended to a multi-band VCO. For example, a three-band VCO would include another pair of varactor diodes and switches to ensure operation of the multi-band VCO in a third operating state.

[0101] Figure 8 It is shown as the control voltage V C Dual-band VCO functions (such as those mentioned above) Figures 2-4 The dual-band VCO 100 described above or related to Figures 5-7 The embodiment relationship of the resonant frequency fVCO of the dual-band VCO 200 described.

[0102] In the first operating mode, the digital signal LR is set to '1' (i.e., high). This causes the switching circuit of the dual-band VCO 100 or 200 to switch the pair of second varactor diodes C. VB The capacitor is set as a fixed capacitor, while the pair of first varactor diodes C VA Tuned to control voltage V C By adjusting the control voltage V C The value of the resonant frequency fVCO is tuned across a long-range radar band, for example, from 38 GHz to 38.5 GHz, and is subsequently increased to 76 GHz to 77 GHz by a frequency multiplier.

[0103] In the second operating mode, the digital signal LR is set to '0' (i.e., low). In the case of the dual-band VCO 100, this causes the switching circuit of the dual-band VCO 100 to switch the pair of first varactor diodes C... VA The capacitor is set as a fixed capacitor, while the pair of second varactor diodes C VB Connected to control voltage V C In the case of a dual-band VCO 200, this causes the switching circuit of the dual-band VCO 200 to switch the pair of first varactor diodes C. VA and the pair of second varactor diodes CVB Connected to control voltage V C Therefore, in the second operating mode, the pair of first varactor diodes C VA and the pair of second varactor diodes C VB It is used to tune the resonant frequency fVCO. By adjusting the value of the control voltage VC, the resonant frequency fVCO is tuned across a short-range radar band, for example, from 38.5 GHz to 40.5 GHz, and is subsequently multiplied by a frequency multiplier to 77 GHz to 81 GHz.

[0104] By tuning the resonant frequency fVCO in the first and second operating modes, the output frequency of the dual-band VCO 100 or 200 can be set in a tuning range of 38.5 GHz to 40.5 GHz, and subsequently increased to 77 GHz to 81 GHz by a frequency multiplier (i.e., across both the long-range radar band and the short-range radar band).

[0105] Figure 9 A block diagram of an embodiment of a processing system 300 for performing the methods described herein is shown. The processing system 300 may be installed in a host device. The processing system 300 includes a controller 302, a memory 304, and a dual-band VCO 306, which may (or may not) be as described... Figure 9 The arrangement is shown. The processing system 300 may include components not shown in... Figure 9 Additional components, such as interfaces or long-term storage devices (e.g., non-volatile memory), are shown. In some embodiments, the processing system 300 is a radar system, such as an automotive radar system.

[0106] Controller 302 is a microcontroller, microprocessor, processor, etc. Controller 302 executes programming for processing system 300, such as functions of advanced driver assistance systems.

[0107] The controller 302 is connected to the memory 304. In some embodiments, the memory 304 may be any component or collection of components suitable for storing programming and / or instructions for the execution of the controller 302. In embodiments, the memory 304 includes a non-transitory computer-readable medium.

[0108] Controller 302 is also connected to dual-band VCO 306. In some embodiments, dual-band VCO 306 is similar to the one described above. Figures 2-4 The dual-band VCO 100 is described. In some embodiments, the dual-band VCO 306 is similar to the one described above. Figures 5-7 The dual-band VCO200 is described.

[0109] Controller 302 provides a digital signal LR to select the operating mode of the dual-band VCO 306 (e.g., operation in a short-range radar band or a long-range radar band). The dual-band VCO 306 provides a tunable resonant frequency across two bands as a reference signal to controller 302. Control voltage V C It is provided by a phase-locked loop (PLL) integrated with controller 302. The digital signal LR can be, for example, a static control bit used in automotive radar applications.

[0110] In some embodiments, controller 302 is also connected to transmitter 308 and receiver 310. Transmitter 308 generates radar signals for measuring distances to nearby objects. Receiver 310 detects reflections of radar signals from nearby objects. Controller 302 operates transmitter 308 and receiver 310 using a reference signal from dual-band VCO 306.

[0111] Figure 10 A flowchart of a method 1000 for operating a dual-band voltage-controlled oscillator (VCO) 100 according to some embodiments is shown. Steps 1004, 1006, 1008, and 1010 may be performed in the order shown, simultaneously, or in any other suitable order.

[0112] In step 1002, the dual-band VCO 100 operates in the first operating mode, wherein the first pair of varactor diodes C VA The resonant frequency fVCO of the dual-band VCO 100 is tuned in the first frequency band, and the second pair of varactor diodes C VB Provide fixed capacitors, as mentioned above. Figure 3 As described.

[0113] In step 1004, the first pair of varactor diodes C are switched off by disconnecting the first switch 152. VA With control voltage V C Disconnect, as mentioned above. Figure 4 As described.

[0114] In step 1006, the second pair of varactor diodes C is switched off by disconnecting the fourth switch 158. VB Disconnect from the reference ground node, as mentioned above. Figure 4 As described.

[0115] In step 1008, the first pair of varactor diodes C are switched on by closing the second switch 154. VA Connected to power supply voltage V DD Terminals, as mentioned above Figure 4 As described.

[0116] In step 1010, the second pair of varactor diodes C is switched on by closing the third switch 156. VB Connected to control voltage V C As mentioned above Figure 4 As described.

[0117] In step 1012, the dual-band VCO 100 operates in the second operating mode, wherein the first pair of varactor diodes C VA Provide a fixed capacitor, and a second pair of varactor diodes C VB The resonant frequency fVCO is tuned in the second frequency band outside the first frequency band, as mentioned above. Figure 4 As described.

[0118] Figure 11 A flowchart of a method 2000 for operating a dual-band voltage-controlled oscillator (VCO) 100 according to some embodiments is shown. Steps 2004, 2006, 2008, and 2010 may be performed in the order shown, simultaneously, or in any other suitable order.

[0119] In step 2002, the dual-band VCO 100 operates in the second operating mode, wherein the first pair of varactor diodes C VA Provide a fixed capacitor, and a second pair of varactor diodes C VB Tune the resonant frequency fVCO of the dual-band VCO 100 in the second frequency band, as mentioned above. Figure 4 As described.

[0120] In step 2004, the first pair of varactor diodes C are switched off by disconnecting the second switch 154. VA Disconnect from the power supply voltage, as mentioned above. Figure 3 As described.

[0121] In step 2006, the second pair of varactor diodes C is switched off by disconnecting the third switch 156. VB Disconnect from the control voltage, as mentioned above. Figure 3 As described.

[0122] In step 2008, the first pair of varactor diodes C are switched on by closing the first switch 152. VA Connect to the control voltage terminal, as described above. Figure 3 As described.

[0123] In step 2010, the second pair of varactor diodes C is switched on by closing the fourth switch 158. VB Connect to the reference ground, as mentioned above. Figure 3 As described.

[0124] In step 2012, the dual-band VCO 100 operates in the first operating mode, wherein the first pair of varactor diodes C VA The resonant frequency fVCO of the dual-band VCO 100 is tuned in the first band outside the second band, and the second pair of varactor diodes C VB Provide fixed capacitors, as mentioned above. Figure 3 As described.

[0125] Figure 12 A flowchart of a method 3000 for operating a dual-band voltage-controlled oscillator (VCO) 200 according to some embodiments is shown. Steps 3004, 3006, and 3010 may be performed in the order shown, simultaneously, or in any other suitable order.

[0126] In step 3002, the dual-band VCO 200 operates in the first operating mode, wherein the first pair of varactor diodes C VA The resonant frequency fVCO of the dual-band VCO 200 is tuned in the first frequency band, and the second pair of varactor diodes C VB A pair of capacitors (first capacitor 242 and second capacitor 244) provide a fixed capacitance, as described above regarding... Figure 7 As described.

[0127] In step 3004, the second pair of varactor diodes C are switched off by disconnecting the first switch 252. VB With power supply voltage V DD The terminal is disconnected, as mentioned above. Figure 7 As described.

[0128] In step 3006, the second pair of varactor diodes C are switched on by closing the second switch 254. VB Connected to control voltage V C As mentioned above Figure 7 As described.

[0129] In step 3008, the first capacitor 242 and the second capacitor 244 are disconnected from each other by turning off the third switch 256, as described above. Figure 7 As described.

[0130] In step 3010, the dual-band VCO 200 operates in the second operating mode, wherein the first pair of varactor diodes C VA The second pair of varactor diodes C VB Tune the resonant frequency fVCO of the dual-band VCO 200 in the second frequency band outside the first frequency band, as mentioned above. Figure 7 As described.

[0131] Figure 13A flowchart of a method 4000 for operating a dual-band voltage-controlled oscillator (VCO) 200 according to some embodiments is shown. Steps 4004, 4006, and 4010 may be performed in the order shown, simultaneously, or in any other suitable order.

[0132] In step 4002, the dual-band VCO 200 operates in the second operating mode, wherein the first pair of varactor diodes C VA The second pair of varactor diodes C VB Tune the resonant frequency fVCO of the dual-band VCO 200 in the second frequency band, as mentioned above. Figure 7 As described.

[0133] In step 4004, the second pair of varactor diodes C are switched on by closing the first switch 252. VB Connected to power supply voltage V DD Terminals, as mentioned above Figure 6 As described.

[0134] In step 4006, the second pair of varactor diodes C are switched off by disconnecting the second switch 254. VB With control voltage V C Disconnect, as mentioned above. Figure 6 As described.

[0135] In step 4008, the first capacitor 242 and the second capacitor 244 are connected to each other by closing the third switch 256, as described above. Figure 6 As described.

[0136] In step 4010, the dual-band VCO 200 operates in the first operating mode, wherein the first pair of varactor diodes C VA The resonant frequency fVCO of the dual-band VCO 200 is tuned in the first band outside the second band, and the second pair of varactor diodes C VB A pair of capacitors (capacitor 242 and capacitor 244) provide a fixed capacitance, as described above regarding... Figure 6 As described.

[0137] Exemplary embodiments of this disclosure are summarized herein. Other embodiments may also be understood from the entire specification and the claims filed herein.

[0138] Example 1. A voltage-controlled oscillator (VCO) circuit includes: a pair of inductors coupled in series; a first pair of varactor diodes coupled in series, a first common-mode node between corresponding varactor diodes of the first pair of varactor diodes; a second pair of varactor diodes coupled in series, a second common-mode node between corresponding varactor diodes of the second pair of varactor diodes, a first terminal of the first pair of varactor diodes coupled to a first terminal of the second pair of varactor diodes and a first terminal of the pair of inductors, and a second terminal of the first pair of varactor diodes coupled to a second terminal of the second pair of varactor diodes and a second terminal of the pair of inductors; a power supply voltage node switchably coupled to the first common-mode node via a first switch, the power supply voltage node being a node located between the pair of inductors; and a control voltage node (V C It can be switched to the second common-mode node via a second switch.

[0139] Example 2. The circuit of Example 1 also includes an oscillator core coupled to an LC energy storage circuit, which includes a first pair of varactor diodes, a second pair of varactor diodes, and a pair of inductors.

[0140] Example 3. The circuit according to one of Examples 1 or 2 further includes: a third switch and a fourth switch, the third switch coupling the control voltage node to the first common-mode node, and the fourth switch coupling the reference ground node to the second common-mode node.

[0141] Example 4. Based on the circuit of Example 1, wherein the first common-mode node is coupled to the second common-mode node via a second switch, and the control voltage node is coupled to the first common-mode node.

[0142] Example 5. The circuit according to Example 4 further includes: a first capacitor, a third switch, and a second capacitor coupled in series; a first terminal of the first capacitor being coupled to a first terminal of a first pair of varactor diodes; a second terminal of the first capacitor being coupled to a first terminal of the third switch; a first terminal of the second capacitor being coupled to a second terminal of the third switch; and a second terminal of the second capacitor being coupled to a second terminal of the first pair of varactor diodes.

[0143] Example 6. A voltage-controlled oscillator (VCO) circuit includes: a resonant circuit comprising a first pair of varactor diodes and a second pair of varactor diodes, the resonant frequency of the resonant circuit depending on a first capacitance of the first pair of varactor diodes and a second capacitance of the second pair of varactor diodes, the resonant frequency setting the output frequency of the VCO circuit; an oscillator core coupled to the resonant circuit; and a switching circuit configured to operate the VCO circuit in a first operating mode and a second operating mode, the switching circuit being configured to select the first pair of varactor diodes for tuning the resonant frequency in a first frequency band in the first operating mode, and the switching circuit being configured to select the second pair of varactor diodes for tuning the resonant frequency in a second frequency band outside the first frequency band in the second operating mode.

[0144] Example 7. The VCO circuit according to Example 6, wherein the first frequency band is between 38 GHz and 38.5 GHz, and the second frequency band is between 38.5 GHz and 40.5 GHz.

[0145] Example 8. A VCO circuit based on one of Examples 6 or 7, where the resonant circuit is a dual-supply voltage circuit.

[0146] Example 9. A VCO circuit according to one of Examples 6 to 8, wherein in a first operating mode, the switching circuit is configured to set each of the second pair of varactor diodes as a fixed capacitor, and wherein in a second operating mode, the switching circuit is configured to set each of the first pair of varactor diodes as a fixed capacitor.

[0147] Example 10. According to the VCO circuit of Example 9, in the first operating mode, the first switch of the switching circuit couples the first common-mode node of the first pair of varactor diodes to the control voltage node.

[0148] Example 11. A VCO circuit according to one of Examples 9 or 10, wherein, in a first operating mode, a second switch of the switching circuit couples a second common-mode node of a second pair of varactor diodes to a ground node.

[0149] Example 12. A VCO circuit according to one of Examples 9 to 11, wherein, in a second operating mode, a third switch of the switching circuit couples the first common-mode node of the first pair of varactor diodes to the power supply voltage node.

[0150] Example 13. A VCO circuit according to one of Examples 9 to 12, wherein, in the second operating mode, the fourth switch of the switching circuit couples the second common-mode node of the second pair of varactor diodes to the control voltage node.

[0151] Example 14. A method of operating a voltage-controlled oscillator (VCO) circuit, comprising: operating the VCO in a first operating mode using a switching circuit, the VCO circuit including a resonant circuit including a first pair of varactor diodes, a second pair of varactor diodes, and a resonant frequency for setting the output frequency of the VCO, the switching circuit setting the first pair of varactor diodes in the first operating mode to tune the resonant frequency in a first frequency band; and operating the VCO in a second operating mode using the switching circuit, the switching circuit setting the second pair of varactor diodes in the second operating mode to tune the resonant frequency in a second frequency band outside the first frequency band.

[0152] Example 15. According to the method of Example 14, wherein the switching circuit sets the first pair of varactor diodes in a first operating mode to tune the resonant frequency in a first frequency band, the method includes: closing a first switch, the first switch coupling the first common-mode node of the first pair of varactor diodes to a control voltage node.

[0153] Example 16. According to one of Examples 14 or 15, operating the VCO in the first operating mode further includes biasing a second pair of varactor diodes to act as fixed capacitors.

[0154] Example 17. According to the method of Example 14, wherein the switching circuit, in a second operating mode, sets up a second pair of varactor diodes to tune the resonant frequency in a second frequency band by closing a second switch, the second switch coupling a second common-mode of the second pair of varactor diodes to a control voltage node.

[0155] Example 18. According to the method of Example 17, operating the VCO in the second operating mode further includes: biasing the first pair of varactor diodes to act as fixed capacitors.

[0156] Example 19. According to the method of Example 14, operating the VCO in the second operating mode further includes: setting a first pair of varactor diodes in a switching circuit to tune the resonant frequency in a second frequency band.

[0157] Example 20. According to the method of Example 19, wherein the switching circuit configures the first pair of varactor diodes to tune the resonant frequency in the second frequency band, the method comprises: closing the first switch, the first switch coupling the first common-mode node of the first pair of varactor diodes to the second common-mode node of the second pair of varactor diodes.

[0158] Example 21. According to one of Examples 14, 19 or 20, operating the VCO in the first operating mode further includes: a switching circuit that couples a pair of capacitors to each other.

[0159] Example 22. A voltage-controlled oscillator (VCO) includes: a plurality of varactor diodes, including a first varactor diode, a second varactor diode, a third varactor diode, and a fourth varactor diode, a first terminal of the first varactor diode being coupled to a first terminal of the third varactor diode, and a first terminal of the second varactor diode being coupled to a first terminal of the fourth varactor diode; a switching circuit including a first switch, a second switch, a third switch, and a fourth switch; a control terminal coupled to a first terminal of the first switch and a first terminal of the third switch; a first common-mode node coupled to a second terminal of the first varactor diode, a second terminal of the second varactor diode, a second terminal of the first switch, and a second terminal of the second switch; and a second common-mode node coupled to a second terminal of the third varactor diode, a second terminal of the fourth varactor diode, a second terminal of the third switch, and a second terminal of the fourth switch.

[0160] Example 23. The VCO according to Example 22 also includes a second control terminal, which is coupled to the control terminals of the first switch, the second switch, the third switch, and the fourth switch.

[0161] Example 24. A voltage-controlled oscillator (VCO) includes: a plurality of varactor diodes, the plurality of varactor diodes including a first varactor diode, a second varactor diode, a third varactor diode, and a fourth varactor diode, wherein in a first operating mode, a first terminal of the first varactor diode and a first terminal of the second varactor diode are coupled to a control voltage node, and the first terminals of the third varactor diode and the fourth varactor diode are coupled to a reference ground node, and wherein in a second operating mode, the first terminals of the first varactor diode and the first terminals of the second varactor diode are coupled to a power supply voltage node, and the first terminals of the third varactor diode and the fourth varactor diode are coupled to a control voltage node; and a plurality of switches, the plurality of switches including a first switch, a second switch, a third switch, and a fourth switch, wherein in the first operating mode, the first switch and the fourth switch are in a closed position, and the second switch and the third switch are in an open position, and wherein in the second operating mode, the first switch and the fourth switch are in an open position, and the second switch and the third switch are in a closed position.

[0162] Example 25. A method comprising: operating a voltage-controlled oscillator (VCO) in a first operating mode, including: coupling a first terminal of a first varactor diode of the VCO and a first terminal of a second varactor diode of the VCO to a control voltage node using a first switch of the VCO; and coupling a first terminal of a third varactor diode of the VCO and a first terminal of a fourth varactor diode of the VCO to a reference ground node using a fourth switch of the VCO; and operating the VCO in a second operating mode, including: coupling a first terminal of the first varactor diode and a first terminal of the second varactor diode to a power supply voltage node using a second switch; and coupling a first terminal of the third varactor diode and a first terminal of the fourth varactor diode to a control voltage node using a third switch.

[0163] Although a detailed description has been provided, it should be understood that various changes, substitutions, and alterations can be made without departing from the spirit and scope of this disclosure as defined by the appended claims. In the various drawings, the same elements are designated by the same reference numerals. Furthermore, the scope of the invention is not intended to be limited to the specific embodiments described herein; those skilled in the art will readily understand from the invention that existing or later-developed processes, machines, manufactures, compositions of matter, apparatuses, methods, or steps can perform substantially the same functions or achieve substantially the same results as the corresponding embodiments described herein. Therefore, the appended claims are intended to include such processes, machines, manufactures, compositions of matter, apparatuses, methods, or steps within their scope.

[0164] Therefore, the specification and drawings should be considered as a description of this disclosure as defined by the appended claims, and are intended to cover any and all modifications, variations, combinations or equivalents falling within the scope of this disclosure.

Claims

1. A voltage controlled oscillator, VCO, circuit comprising: a pair of inductors coupled in series; a first pair of varactor diodes coupled in series, a first common mode node between respective varactor diodes of the first pair of varactor diodes; a second pair of varactor diodes coupled in series, a second common mode node between respective varactor diodes of the second pair of varactor diodes, a first terminal of the first pair of varactor diodes coupled to a first terminal of the second pair of varactor diodes and a first terminal of the pair of inductors, and a second terminal of the first pair of varactor diodes coupled to a second terminal of the second pair of varactor diodes and a second terminal of the pair of inductors; a power supply voltage node (V DD ) switchably coupled to the first common mode node (126) by a first switch (154), the power supply voltage node (V DD ) being a node between the pair of inductors; and a control voltage node (V C ), switchably coupled to the second common mode node (136) by a second switch (156), wherein the first common mode node (126) is coupled to the second common mode node (136) through the second switch (156) and a third switch (152).

2. The circuit of claim 1, further comprising an oscillator core coupled to an LC tank circuit, the LC tank circuit comprising the first and second pairs of varactor diodes and the pair of inductors.

3. The circuit of claim 1, further comprising a third switch (152) and a fourth switch (158), the third switch (152) coupling the control voltage node (V C ) to the first common mode node (126), the fourth switch (158) coupling a reference ground node to the second common mode node (136).

4. The circuit of claim 1, further comprising: a first capacitor, a fifth switch (256) and a second capacitor coupled in series; a first terminal of the first capacitor coupled to a first terminal of the first pair of varactor diodes; a second terminal of the first capacitor coupled to a first terminal of the fifth switch (256); a first terminal of the second capacitor coupled to a second terminal of the fifth switch (256); and a second terminal of the second capacitor coupled to a second terminal of the first pair of varactor diodes.

5. A voltage controlled oscillator, VCO, circuit comprising: a resonant circuit comprising a first pair of varactor diodes and a second pair of varactor diodes, a resonant frequency of the resonant circuit dependent on a first capacitance of the first pair of varactor diodes and a second capacitance of the second pair of varactor diodes, the resonant frequency setting an output frequency of the VCO circuit; an oscillator core coupled to the resonant circuit; and a switch circuit configured to operate the VCO circuit in a first operating mode and a second operating mode, the switch circuit configured to select the first pair of varactor diodes for tuning the resonant frequency over a first frequency band in the first operating mode, and the switch circuit configured to select the second pair of varactor diodes for tuning the resonant frequency over a second frequency band outside the first frequency band in the second operating mode, wherein the switch circuit comprises a first switch (152), a second switch (158), a third switch (154) and a fourth switch (156), and wherein a first common mode node (126) of the first pair of varactor diodes is coupled to a second common mode node (136) of the second pair of varactor diodes through the first switch (152) and the fourth switch (156).

6. The VCO circuit of claim 5, wherein the first frequency band is between 38 GHz and 38.5 GHz, and the second frequency band is between 38.5 GHz and 40.5 GHz. ​ ​ 7. The VCO circuit of claim 5, wherein in the first mode of operation, the switch circuit is configured to set each varactor diode of the second pair of varactor diodes as a fixed capacitor, and wherein in the second mode of operation, the switch circuit is configured to set each varactor diode of the first pair of varactor diodes as a fixed capacitor.

8. The VCO circuit of claim 7, wherein in the first mode of operation, the first switch of the switch circuit couples the first common mode node of the first pair of varactor diodes to a control voltage node.

9. The VCO circuit of claim 7, wherein in the first mode of operation, the second switch of the switch circuit couples the second common mode node of the second pair of varactor diodes to a ground node.

10. The VCO circuit of claim 7, wherein in the second mode of operation, the third switch of the switch circuit couples the first common mode node of the first pair of varactor diodes to a power supply voltage node.

11. The VCO circuit of claim 7, wherein in the second mode of operation, the fourth switch of the switch circuit couples the second common mode node of the second pair of varactor diodes to a control voltage node.

12. A method of operating a voltage controlled oscillator (VCO) circuit, the method comprising: operating the VCO in a first mode of operation using a switch circuit, the VCO circuit including a resonant circuit including a first pair of varactor diodes, a second pair of varactor diodes, and a resonant frequency setting an output frequency of the VCO, the switch circuit setting the first pair of varactor diodes to tune the resonant frequency over a first frequency band in the first mode of operation; and operating the VCO in a second mode of operation using the switch circuit, the switch circuit setting the second pair of varactor diodes to tune the resonant frequency over a second frequency band outside the first frequency band in the second mode of operation, wherein the switch circuit includes a first switch (152), a second switch (158), a third switch (154), and a fourth switch (156), and wherein a first common mode node (126) of the first pair of varactor diodes is coupled to a second common mode node (136) of the second pair of varactor diodes through the first switch (152) and the fourth switch (156).

13. The method of claim 12, wherein the switch circuit, in the first operating mode, setting the first pair of varactor diodes to tune the resonant frequency over the first frequency band comprises: closing the first switch that couples the first common mode node of the first pair of varactor diodes to a control voltage node.

14. The method of claim 12, wherein operating the VCO in the first mode of operation further comprises: biasing the second pair of varactor diodes to act as fixed capacitors.

15. The method of claim 12, wherein the switch circuit setting the second pair of varactor diodes to tune the resonant frequency over the second frequency band in the second mode of operation comprises: closing the second switch that couples the second common mode node of the second pair of varactor diodes to a control voltage node.

16. The method of claim 15, wherein operating the VCO in the second mode of operation further comprises: biasing the first pair of varactor diodes to act as fixed capacitors.

17. The method of claim 12, wherein operating the VCO in the second mode of operation further comprises: the switch circuit setting the first pair of varactor diodes to tune the resonant frequency over the second frequency band.

18. The method of claim 17, wherein the switch circuitry sets the first pair of varactor diodes to tune the resonant frequency on the second frequency band comprises: The first switch (152) and the fourth switch (156) that close couple the first common mode node of the first pair of varactor diodes with the second common mode node of the second pair of varactor diodes.

19. The method of claim 12, wherein operating the VCO in the first mode of operation further comprises: The switch circuit couples a pair of capacitors to each other.

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