Oscillating circuit and chip

Abstract

The present invention provides an oscillation circuit and a chip. The oscillation circuit comprises a feedback voltage generating circuit, which generates a feedback voltage based on the oscillation frequency of a feedback oscillation signal; a first amplifier, which generates a corresponding control signal based on a first reference voltage and a feedback voltage; an oscillator generates an oscillation signal based on the control signal; a chopping circuit, which is connected to the feedback voltage generating circuit to receive the feedback voltage and the first reference voltage, performs chopping processing on the first reference voltage and the feedback voltage, modulates the noise voltage and deviation voltage caused by the first amplifier in the feedback voltage to a high frequency band, and transmits the feedback voltage and the first reference voltage after the chopping processing to the first amplifier; a low-pass filter, which is connected between the oscillator and the first amplifier, filters the noise voltage and deviation voltage in the high frequency band in the control signal output by the first amplifier, and transmits the filtered control signal to the oscillator, so that the oscillator can generate an oscillation signal with a stable oscillation frequency.

Description

Technical Field

[0001] The present invention relates to the field of integrated circuit technology, and in particular to an oscillating circuit and a chip. Background Art

[0002] Low-temperature drift oscillators in the prior art generally use switched capacitor technology to ensure relatively good frequency-temperature characteristics. Low-temperature drift oscillators generally integrate an amplifier circuit, which has its own natural deviation Voffset and device noise Vnoise. The amplifier circuit's Voffset itself has a temperature coefficient, which affects the oscillator's frequency stability. While Vnoise does not cause temperature stability issues in the long term, its inherent characteristics, especially the significant low-frequency component of device noise, can lead to poor stability of the oscillation frequency of the oscillator's output signal over time. Therefore, existing low-temperature drift oscillators need to be improved. Summary of the Invention

[0003] The present invention provides an oscillator circuit and a chip. The oscillator circuit can generate an oscillation signal with a stable oscillation frequency.

[0004] To solve the above technical problems, the first technical solution provided by the present invention is: to provide an oscillation circuit, comprising: a feedback voltage generating circuit, for generating a feedback voltage based on the oscillation frequency of a feedback oscillation signal; a first amplifier, for generating a corresponding control signal based on a first reference voltage and the feedback voltage; an oscillator, for generating the oscillation signal based on the control signal; a chopping circuit, connected to the feedback voltage generating circuit to receive the feedback voltage and the first reference voltage, to chop the first reference voltage and the feedback voltage, frequency-modulate the noise voltage and the deviation voltage caused by the first amplifier in the feedback voltage to a high frequency band, and transmit the chopped feedback voltage and the first reference voltage to the first amplifier; a low-pass filter, connected between the oscillator and the first amplifier, to filter the high-frequency noise voltage and the deviation voltage in the control signal output by the first amplifier, and transmit the filtered control signal to the oscillator, so that the oscillator can generate the oscillation signal with a stable oscillation frequency.

[0005] The chopping circuit is further connected to the oscillator to perform chopping processing based on the oscillation frequency of the oscillation signal generated by the oscillator, thereby frequency-modulating the noise voltage and the deviation voltage in the feedback voltage to a high frequency band.

[0006] The oscillation circuit further includes: a frequency divider connected between the chopping circuit and the oscillator, so that the chopping circuit is connected to the oscillator through the frequency divider, thereby dividing the oscillation frequency of the oscillation signal generated by the oscillator by the frequency divider to obtain a divided signal with a divided frequency, and inputting the divided signal into the chopping circuit, so that the chopping circuit performs chopping processing based on the divided frequency generated by the oscillation frequency, thereby frequency-modulating the noise voltage and the deviation voltage in the feedback voltage to a high frequency band.

[0007] In which, the first amplifier includes a first input terminal, a second input terminal and an output terminal, and the chopping circuit includes a first input terminal, a second input terminal, a first output terminal and a second output terminal, wherein the first input terminal of the chopping circuit is used to receive the first reference voltage, the second input terminal of the chopping circuit is used to connect the feedback voltage generating circuit to receive the feedback voltage, the first output terminal of the chopping circuit is used to connect the first input terminal of the first amplifier to output the first reference voltage after chopping processing to the first amplifier, and the second output terminal of the chopping circuit is used to connect the second input terminal of the first amplifier to output the feedback voltage after chopping processing to the first amplifier.

[0008] The low-pass filter includes: a first resistor connected between the output end of the first amplifier and the oscillator; and a first capacitor connected between a first node between the first resistor and the oscillator and a ground voltage.

[0009] The feedback voltage generating circuit includes: a reference current source for providing a reference current with low temperature drift; a switched capacitor circuit connected to the reference current source and the output end of the oscillator, and controlling the switched capacitor circuit based on the oscillation frequency of the feedback oscillation signal, so that the switched capacitor circuit is equivalent to an equivalent resistor, thereby enabling the switched capacitor circuit to generate the feedback voltage based on the reference current, wherein the feedback voltage is a feedback voltage with low temperature drift.

[0010] The switched capacitor circuit includes: a first switch; a second switch, wherein the first switch and the second switch are connected in series between the output end of the reference current source and the ground voltage; the connection point between the first switch and the output end of the reference current source serves as the output end of the feedback voltage generating circuit to output the feedback voltage; the control end of the second switch receives the fed-back oscillation signal to perform switching based on the oscillation frequency of the oscillation signal; the control end of the first switch receives the fed-back oscillation signal through an inverter to perform switching based on the oscillation frequency of the inverse signal of the oscillation signal; and a second capacitor connected between a second node between the first switch and the second switch and the ground voltage.

[0011] The feedback voltage generating circuit further includes: a decoupling capacitor connected in parallel with the switch capacitor circuit between the output end of the reference current source and the ground voltage.

[0012] The reference current source includes: a first transistor, a second transistor of the same type as the first transistor and proportional to the size of the first transistor, wherein the first channel end of the first transistor is connected to the first channel end of the second transistor, the control end of the first transistor is connected to the control end of the second transistor, and the second channel end of the second transistor serves as the output end of the feedback voltage generating circuit; a third transistor, whose first channel end is connected to the second channel end of the first transistor, wherein the second channel end of the first transistor is connected to the control end of the first transistor; a second amplifier, whose first input end is used to receive a second reference voltage, and whose output end is connected to the control end of the third transistor; a second resistor, connected between the second channel end of the third transistor and the ground voltage, wherein a third node between the second resistor and the second channel end of the third transistor is connected to the second input end of the second amplifier.

[0013] The second resistor is a low-temperature drift resistor inside the chip or a low-temperature drift resistor outside the chip.

[0014] In order to solve the above technical problems, the second technical solution provided by the present invention is: providing a chip, the chip including any one of the above-mentioned oscillation circuits.

[0015] The beneficial effects of the present invention are different from those of the prior art. The oscillation circuit provided by the present invention chops the first reference voltage and the feedback voltage through a chopping circuit, and frequency-modulates the noise voltage and bias voltage caused by the first amplifier in the feedback voltage to a high frequency band; and filters the high-frequency noise voltage and bias voltage in the control signal output by the first amplifier through a low-pass filter, and transmits the filtered control signal to the oscillator, thereby enabling the oscillator to generate the oscillation signal with a stable oscillation frequency. The oscillation frequency of the oscillation signal generated by the oscillation circuit of the present application is more stable than that of the oscillation signal generated by the oscillation circuit in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive work, among which:

[0017] Figure 1 Schematic diagram of the functional modules of the first embodiment of the oscillation circuit of the present invention;

[0018] Figure 2 Schematic diagram of the functional modules of the second embodiment of the oscillation circuit of the present invention;

[0019] Figure 3 1 is a functional module diagram of a third embodiment of an oscillator circuit according to the present invention;

[0020] Figure 4 for Figure 3 A schematic structural diagram of a specific embodiment of an oscillator circuit is shown;

[0021] Figure 5a A schematic diagram of the oscillation frequency of an oscillation signal output by an oscillation circuit in the prior art;

[0022] Figure 5b A schematic diagram of the oscillation frequency of the oscillation signal output by the oscillation circuit of the present invention;

[0023] Figure 6 FIG. 1 is a schematic structural diagram of a chip according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0025] See Figure 1 , is a functional module diagram of an embodiment of the oscillation circuit of the present invention. Specifically, the oscillation circuit of the present application includes: a feedback voltage generating circuit 11, a first amplifier 12, an oscillator 13, a chopper circuit 14 and a low-pass filter 15.

[0026] The feedback voltage generating circuit 11 is configured to generate a feedback voltage V1 based on the oscillation frequency f of the feedback oscillation signal T. The first amplifier 12 is configured to generate a corresponding control signal P based on a first reference voltage Vref1 and the feedback voltage V1. The oscillator 13 generates the oscillation signal T based on the control signal P. The chopping circuit 14 is connected to the feedback voltage generating circuit 11 to receive the feedback voltage V1 and the first reference voltage Vref1. The chopping circuit 14 chops the first reference voltage Vref1 and the feedback voltage V1, modulating the noise voltage and offset voltage in the feedback voltage V1 caused by the first amplifier 12 to a high frequency band. The chopped feedback voltage V1 and the first reference voltage Vref1 are then transmitted to the first amplifier 12. A low-pass filter 15 is connected between the oscillator 13 and the first amplifier 12 to filter the high-frequency noise voltage and offset voltage in the control signal P output by the first amplifier 12. The low-pass filter 15 transmits the filtered control signal P to the oscillator 13, thereby enabling the oscillator 13 to generate the oscillation signal T having a stable oscillation frequency f.

[0027] Specifically, in this embodiment, the feedback voltage V1 is generated based on the oscillation frequency f of the feedback oscillation signal T. The oscillation signal T is output via the first amplifier 12 and the oscillator 13. This means that the oscillation signal T causes the generated feedback voltage V1 to contain noise voltage and offset voltage caused by the first amplifier 12. A chopper circuit 14 is provided to frequency-modulate the noise voltage and offset voltage caused by the first amplifier 12 in the feedback voltage V1 to a high frequency band. A low-pass filter 15 is also provided to filter the high-frequency noise voltage and offset voltage in the control signal P output by the first amplifier 12. The processed (i.e., chopped and filtered) control signal P is ultimately input to the oscillator 13, enabling the oscillator 13 to generate the oscillation signal T having a stable oscillation frequency f.

[0028] In one embodiment, if Figure 2 As shown, the chopping circuit 14 is further connected to the oscillator 13 to perform a chopping process based on the oscillation frequency f of the oscillation signal T generated by the oscillator 13, thereby frequency-modulating the noise voltage and the offset voltage in the feedback voltage V1 to a high frequency band. Specifically, the chopping circuit 14 performs a chopping process on the first reference voltage Vref1 and the feedback voltage V1 based on the oscillation frequency f of the oscillation signal T, thereby frequency-modulating the noise voltage and the offset voltage in the feedback voltage V1 to a high frequency band.

[0029] In another embodiment, the oscillation circuit further includes a frequency divider 16 connected between the chopping circuit 14 and the oscillator 13, such that the chopping circuit 14 is connected to the oscillator 13 via the frequency divider 16. The frequency divider 16 divides the oscillation frequency f of the oscillation signal T generated by the oscillator 13 to generate a frequency-divided signal X having a frequency-divided frequency f1. The frequency-divided signal X is input to the chopping circuit 14, causing the chopping circuit 14 to perform a chopping process based on the frequency-divided frequency f1 generated from the oscillation frequency f, thereby frequency-modulating the noise voltage and the offset voltage in the feedback voltage V1 to a high frequency band. Specifically, the chopping circuit 14 performs a chopping process on the first reference voltage Vref1 and the feedback voltage V1 based on the generated frequency-divided frequency f1, thereby frequency-modulating the noise voltage and the offset voltage in the feedback voltage V1 to a high frequency band.

[0030] Please combine Figure 4 , Figure 4 The figure is a schematic diagram of a specific circuit structure of an embodiment of the oscillator circuit of the present invention. The first amplifier P1 includes a first input terminal, a second input terminal, and an output terminal. The chopper circuit 14 includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal.

[0031] In which, the first input end of the chopping circuit 14 is used to receive the first reference voltage Vref1, the second input end of the chopping circuit 14 is used to connect the feedback voltage generating circuit 11 to receive the feedback voltage V1, the first output end of the chopping circuit 14 is used to connect the first input end of the first amplifier P1 to output the reference voltage after chopping processing to the first amplifier P1, and the second output end of the chopping circuit 14 is used to connect the second input end of the first amplifier P1 to output the feedback voltage after chopping processing to the first amplifier P1.

[0032] The low-pass filter 15 includes a first resistor R1 and a first capacitor C1. The first resistor R1 is connected between the output terminal of the first amplifier P1 and the oscillator 13. The first capacitor C1 is connected between a first node n1 between the first resistor R1 and the oscillator 13 and the ground voltage.

[0033] In one embodiment, the first reference voltage Vref1 and the second reference voltage Vref2 can be generated by a voltage reference circuit or supplied externally, without limitation. The integration circuit formed by the first resistor R1, the first capacitor C1, and the first amplifier P1 can be replaced by a low-pass filter circuit of another configuration.

[0034] In one embodiment, the feedback voltage generating circuit 11 includes a reference current source 111 , a switched capacitor circuit 112 , and a decoupling capacitor Cc.

[0035] The reference current source 111 is used to provide a low-drift reference current. The switched capacitor circuit 112 is connected to the reference current source 111 and the output terminal of the oscillator VCO. The switched capacitor circuit 112 is controlled based on the oscillation frequency f of the feedback oscillation signal T, making the switched capacitor circuit 112 equivalent to an equivalent resistor, thereby causing the switched capacitor circuit 112 to generate the feedback voltage V1 based on the reference current. The feedback voltage V1 is a low-drift feedback voltage. The temperature coefficient of the feedback voltage V1 is the temperature coefficient of R2 / R3. Because the reference current I is the temperature coefficient of R2 / R3, V=IR, and the feedback voltage V1 is also the temperature coefficient of R2 / R3, where R2 is the resistance value of the second resistor R2 and R3 is the resistance value of the third resistor R3.

[0036] In one embodiment, the switched capacitor circuit 112 includes: a first switch S1, a second switch S2, and a second capacitor C2. The first switch S1 and the second switch S2 are connected in series between the output terminal n2 of the reference current source 111 and the ground voltage; the connection point between the first switch S1 and the output terminal n2 of the reference current source 111 serves as the output terminal of the feedback voltage generating circuit 11 to output the feedback voltage V1; the control terminal of the second switch S2 receives the feedback oscillation signal T and switches based on the oscillation frequency f of the oscillation signal T; the control terminal of the first switch S1 receives the feedback oscillation signal T through an inverter Y and switches based on the oscillation frequency of the inverse signal of the oscillation signal T; and the second capacitor C2 is connected between a second node n3 between the first switch S1 and the second switch S2 and the ground voltage.

[0037] The decoupling capacitor Cc and the switched capacitor circuit 112 are connected in parallel between the output terminal of the reference current source 111 and the ground voltage.

[0038] The reference current source 111 includes a first transistor M1, a second transistor M2, a third transistor M3, a second amplifier P2, and a second resistor R2. The second transistor M2 is of the same type as the first transistor M1 and has a size proportional to the first transistor M1. The first channel end of the first transistor M1 is connected to the first channel end of the second transistor M2, the control end of the first transistor M1 is connected to the control end of the second transistor M2, and the second channel end of the second transistor M2 serves as the output end of the feedback voltage generating circuit 11 to output the feedback voltage V1.

[0039] The first path end of the third transistor M3 is connected to the second path end of the first transistor M1, and the second path end of the first transistor M1 is connected to the control end of the first transistor M1. The first input end of the second amplifier P2 is used to receive the second reference voltage Vref2, and the output end thereof is connected to the control end of the third transistor M2. The second resistor R2 is connected between the second path end of the third transistor M3 and the ground voltage, and a third node n4 between the second resistor R2 and the second path end of the third transistor M3 is connected to the second input end of the second amplifier P2. In one embodiment, the second resistor R2 is a low-temperature drift resistor inside the chip, or a low-temperature drift resistor outside the chip, such as Figure 4 As shown, the second resistor R2 is an off-chip low-temperature drift resistor, and the second resistor R2 is R3.

[0040] In the present application, the second capacitor C2 is generally an integrated metal-dielectric-metal structure capacitor. The temperature stability of this capacitor can reach <1 ppm, so it will not affect the temperature coefficient of the oscillator 13. Figure 4 The second resistor R2 or R3 provides a reference current source. If the second resistor R2 is integrated into the chip, R3 is not required. If the second resistor R2 is not integrated into the chip, R3 is set outside the chip to ensure the temperature stability of the reference current. The decoupling capacitor Cc is mainly used to reduce the ripple at the second input terminal of the first amplifier P1. The material of the decoupling capacitor Cc is not limited.

[0041] In this embodiment, the formula R = 1 / (fx C) for a switched capacitor circuit is used to obtain an equivalent resistance R, where f is the oscillation frequency of the oscillation signal T. When a reference current is applied to the decoupling capacitor Cc and the equivalent resistor R, a feedback voltage is generated. The operational amplifier amplifies the difference between Vref1 and this voltage to control the voltage-controlled oscillator, thereby obtaining an oscillator with good temperature stability. Specifically, an oscillator 13 generates an oscillation signal T. The feedback voltage generating circuit 11 generates a feedback voltage V1 based on the oscillation frequency f of the oscillation signal T. The chopper circuit 14 chops the first reference voltage Vref1 and the feedback voltage V1, and frequency-modulates the noise voltage and deviation voltage caused by the first amplifier P1 in the feedback voltage V1 to a high frequency band. The low-pass filter 15 filters the high-frequency noise voltage and deviation voltage in the control signal P output by the first amplifier P1, and inputs the filtered control signal P into the oscillator 13, thereby enabling the oscillator 13 to generate an oscillation signal with a stable oscillation frequency, thereby obtaining an oscillation signal with good temperature stability and frequency stability.

[0042] like Figure 5a and Figure 5b As shown, Figure 5a is the noise spectrum characteristic of the amplifier in the prior art, Figure 5b is the noise spectrum characteristic of the amplifier in this application. Figure 5a and Figure 5b As shown by the comparison, in the oscillation circuit of the present application, the oscillation frequency of the oscillation signal output by the oscillator is significantly more stable than the oscillation frequency of the oscillation signal output by the oscillator in the prior art.

[0043] Specifically, the oscillation circuit of the present invention eliminates the influence of the noise voltage and the deviation voltage on the oscillation frequency of the oscillation signal by processing the noise voltage and the deviation voltage, and can obtain an oscillation signal with a more stable oscillation frequency.

[0044] See Figure 6 , is a schematic structural diagram of an embodiment of a chip provided by the present invention. Specifically, chip 60 includes an oscillator circuit 61, which is the oscillator circuit described above and is capable of generating an oscillation signal with a more stable oscillation frequency. Chip 60 can be applied to battery management, industrial control, communications, consumer electronics, wearable devices, and other fields, without limitation.

[0045] The above are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An oscillator circuit, characterized in that: include: A feedback voltage generating circuit, used for generating a feedback voltage based on an oscillation frequency of a feedback oscillation signal; A first amplifier, configured to generate a corresponding control signal based on a first reference voltage and the feedback voltage; an oscillator, generating the oscillation signal based on the control signal; a chopper circuit connected to the feedback voltage generating circuit to receive the feedback voltage and the first reference voltage, so as to chop the first reference voltage and the feedback voltage, frequency-modulate the noise voltage and the deviation voltage caused by the first amplifier in the feedback voltage to a high frequency band, and transmit the feedback voltage and the first reference voltage after the chopping process to the first amplifier; A low-pass filter is connected between the oscillator and the first amplifier to filter the noise voltage and the deviation voltage in the high-frequency band of the control signal output by the first amplifier, and transmits the filtered control signal to the oscillator, so that the oscillator can generate the oscillation signal with a stable oscillation frequency.

2. The oscillation circuit according to claim 1, characterized in that: The chopping circuit is further connected to the oscillator to perform chopping processing based on the oscillation frequency of the oscillation signal generated by the oscillator, thereby frequency-modulating the noise voltage and the deviation voltage in the feedback voltage to a high frequency band.

3. The oscillation circuit according to claim 2, characterized in that: Further including: A frequency divider is connected between the chopper circuit and the oscillator, so that the chopper circuit is connected to the oscillator through the frequency divider, thereby dividing the oscillation frequency of the oscillation signal generated by the oscillator by the frequency divider to obtain a divided signal with a divided frequency, and the divided signal is input to the chopper circuit, so that the chopper circuit performs chopping processing based on the divided frequency generated by the oscillation frequency, thereby frequency modulating the noise voltage and the deviation voltage in the feedback voltage to a high frequency band.

4. The oscillation circuit according to claim 1, characterized in that: The first amplifier includes a first input terminal, a second input terminal and an output terminal, and the chopper circuit includes a first input terminal, a second input terminal, a first output terminal and a second output terminal, wherein the first input terminal of the chopper circuit is used to receive the first reference voltage, the second input terminal of the chopper circuit is used to connect the feedback voltage generating circuit to receive the feedback voltage, the first output terminal of the chopper circuit is used to connect the first input terminal of the first amplifier to output the first reference voltage after chopping to the first amplifier, and the second output terminal of the chopper circuit is used to connect the second input terminal of the first amplifier to output the feedback voltage after chopping to the first amplifier.

5. The oscillation circuit according to claim 4, characterized in that: The low pass filter comprises: a first resistor connected between an output terminal of the first amplifier and the oscillator; The first capacitor is connected between a first node between the first resistor and the oscillator and a ground voltage.

6. The oscillation circuit according to claim 4, characterized in that: The feedback voltage generating circuit comprises: A reference current source, used to provide a reference current with low temperature drift; A switched capacitor circuit is connected to the reference current source and the output end of the oscillator, and controls the switched capacitor circuit based on the oscillation frequency of the feedback oscillation signal, so that the switched capacitor circuit is equivalent to an equivalent resistor, so that the switched capacitor circuit generates the feedback voltage based on the reference current, wherein the feedback voltage is a low-temperature drift feedback voltage.

7. The oscillation circuit according to claim 6, characterized in that: The switched capacitor circuit comprises: First switch; a second switch, wherein the first switch and the second switch are connected in series between the output terminal of the reference current source and the ground voltage; a connection point between the first switch and the output terminal of the reference current source serves as an output terminal of the feedback voltage generating circuit to output the feedback voltage; a control terminal of the second switch receives the fed-back oscillation signal to switch based on the oscillation frequency of the oscillation signal; a control terminal of the first switch receives the fed-back oscillation signal through an inverter to switch based on the oscillation frequency of the inverse signal of the oscillation signal; The second capacitor is connected between a second node between the first switch and the second switch and the ground voltage.

8. The oscillation circuit according to claim 6, characterized in that: The feedback voltage generating circuit further comprises: A decoupling capacitor is connected in parallel with the switch capacitor circuit between the output end of the reference current source and the ground voltage.

9. The oscillation circuit according to claim 6, characterized in that: The reference current source comprises: The first transistor, a second transistor of the same type as the first transistor and proportional to the size of the first transistor, wherein a first channel end of the first transistor is connected to a first channel end of the second transistor, a control end of the first transistor is connected to a control end of the second transistor, and a second channel end of the second transistor serves as an output end of the feedback voltage generating circuit; a third transistor, a first channel end of which is connected to the second channel end of the first transistor, wherein the second channel end of the first transistor is connected to the control end of the first transistor; A second amplifier, a first input terminal of which is used to receive a second reference voltage, and an output terminal of which is connected to the control terminal of the third transistor; The second resistor is connected between the second channel end of the third transistor and the ground voltage, wherein a third node between the second resistor and the second channel end of the third transistor is connected to the second input end of the second amplifier.

10. The oscillation circuit according to claim 9, characterized in that: The second resistor is a low-temperature drift resistor inside the chip, or a low-temperature drift resistor outside the chip.

11. A chip, characterized in that: Comprising an oscillator circuit as described in any one of claims 1-10.

Images