TWI440299B - Voltage controlled oscillating device - Google Patents

Description

Voltage controlled oscillation device

The present invention relates to a voltage controlled oscillating device, and more particularly to a voltage controlled oscillating device operable in a wide frequency band.

Voltage-controlled oscillating devices are commonly used in various electronic devices in daily life, such as wireless transceiver systems for mobile phones, high-frequency measuring instruments, or analog digital broadcasting systems. The main function is to raise the original signal of lower frequency to Higher frequency carrier.

Referring to FIG. 1, a voltage controlled oscillating device 9 includes an inductor-capacitor resonant circuit 91, an interleaved coupling pair 92, and a voltage controlled current source 93.

The interleaved coupling pair 92 includes two NMOS transistors M ₁ , M ₂ , and the gates of each other are cross-connected with the other of the drains, and the voltage-controlled current source 93 is used to supply a fixed current to the NMOS transistors M ₁ , M ₂ . The input impedance of the interleaved coupling pair 92 can be regarded as a negative resistance, and the absolute value of the negative impedance is equal to the resistance value of the inductance-capacitance resonant circuit 91 to offset the parasitic resistance of the inductance-capacitance resonant circuit 91, when the absolute value of the negative impedance is greater than When the resistance value of the inductance-capacitance resonant circuit 91 is obtained, the interlaced coupling pair 92 can generate an oscillation signal.

The inductor-capacitor resonant circuit 91 includes two sets of inductors L _D1 , L _D2 , a varactor 911 connected between the two sets of inductors L _D1 , L _D2 , a bias resistor R _B , a fixed voltage terminal V _DD , and a Control voltage terminal V _ctrl and two outputs , Wherein, the equivalent inductance values of the two sets of inductors L _D1 and L _D2 are L, and the equivalent capacitance of the varactor 911 is C for generating the resonance frequency 1/2π . If it is desired to adjust the output frequency, the control voltage of the control voltage terminal V _ctrl can be changed to change the capacitance value of the varactor 911, and thus, the two outputs of the voltage controlled oscillating device 9 The frequency of the outputted oscillating signal also changes.

However, the adjustable capacitance range C _min to C _{max of the} varactor 911 of the inductor-capacitor resonant circuit 91 can only obtain a limited frequency range; 1/2π To 1/2π In addition, the wide frequency band range cannot be obtained. In addition, the relevant parameters of the voltage controlled oscillation device 9 include output voltage amplitude, phase noise, etc., and it is generally desired that the amplitude of the output voltage is large to reduce phase noise.

Accordingly, it is an object of the present invention to provide a voltage controlled oscillation device which can obtain a wide frequency band range, has a large amplitude of an output voltage, and reduces phase noise.

Thus, the voltage controlled oscillating device of the present invention comprises an inductor-capacitor resonant circuit, an interleaved coupling pair and two sets of feedback varactors.

The inductor-capacitor resonant circuit has a first control terminal and two output terminals that receive a first control voltage, and has an inductor module and a capacitor module electrically connected to the first control terminal and the two output terminals, and the inductor module The module and the capacitor module change the frequency of an outputted oscillation signal as the first control voltage changes.

The interleaved coupling pair includes two NMOS transistors electrically connected to the two output ends, and the gates of each other are cross-connected with the other of the drains, and the positive bias source of the voltage-controlled oscillating device is connected via the inductor module, The absolute value of the negative impedance generated by the interleaved coupling pair is greater than the equivalent resistance value of the inductor-capacitor resonant circuit, so that the interlaced coupling pair generates the oscillation signal.

Each of the feedback transformers has two connection ends, and the two connection ends of the respective feedback transformers are respectively connected to the 汲 terminal and the source terminal of each NMOS transistor, and each has a second control voltage for synchronous adjustment. The second control end is such that the frequency adjustment range Δ f of the oscillation signal is:

Wherein, L _{D 1 1 is} the equivalent inductance value of the inductance module, Δ C _{var1 is} the equivalent adjustable capacitance value of the capacitor module, and Δ C _var2 , 3 is the equivalent of the two sets of feedback _varactors Adjustable capacitance value.

In this embodiment, the voltage-controlled oscillating device further includes two sets of inductors respectively connected to the source terminals of the NMOS transistors, so that the frequency adjustment range Δ f of the oscillating signal is:

Where L _{D 11 is} the equivalent inductance value of the inductor module, L _S is the equivalent inductance value of the two sets of inductors, Δ C _{var1 is} the equivalent adjustable capacitance value of the capacitor module, and Δ C _{var2 3 is} the equivalent adjustable capacitance value of the two sets of feedback varactors.

In this embodiment, the voltage-controlled oscillating device further includes two buffer amplifiers respectively connected between the 汲 terminal of each NMOS transistor and each of the output terminals, and the gate terminal of each of the buffer amplifiers passes through the inductor module. A positive bias source is connected to the voltage controlled oscillating device.

In this embodiment, each of the buffer amplifiers of the voltage controlled oscillation device cooperates with a buffer amplifier positive bias source, and includes a common source stage transistor, an output inductor, a base resistor, and an output capacitor. The common source stage The source of the transistor is connected in an extreme manner, and the gate terminal of the common source transistor receives the oscillation signal outputted by the inductor-capacitor resonant circuit, and the base terminal of the common source transistor is connected to the base bias via the base resistor. The 汲 terminal of the common source transistor is connected to the buffer amplifier positive bias source via the output inductor.

The function of the voltage-controlled oscillating device of the present invention is to increase the frequency adjustment range of the oscillating signal by providing two sets of feedback varactors, and increase the amplitude of the output voltage of the voltage-controlled oscillating device by providing two sets of feedback varactors. At the same time, reduce phase noise.

The foregoing and other objects, features, and advantages of the invention are set forth in the <RTIgt;

Referring to FIG. 2, in a preferred embodiment of the present invention, the voltage controlled oscillating device 100 includes an inductor-capacitor resonant circuit 2, an interleaved coupling pair 3, and two sets of feedback varactors 11, 12.

The inductor-capacitor resonant circuit 2 has a first control terminal 101 and two output terminals 211, 212 that receive a first control voltage V _ctrl1 and has an inductance module electrically connected to the first control terminal 101 and the two output terminals 211, 212. The group 21 and a capacitor module 22, and the capacitor module 22 changes with the first control voltage V _ctrl1 , and the frequency of the oscillation signal outputted from the output terminals 211 and 212 also changes.

The interlaced pair 3 includes two NMOS transistors M ₁ , M ₂ electrically connected to the two output ends 211 , 212 , respectively , and the gates of each other are cross-connected with the other of the drains, and are connected via the inductor module 21 . The voltage controlled oscillating device positively biases the source 201. The absolute value of the negative impedance generated by the interleaved coupling pair 3 is greater than the equivalent resistance value of the OLED resonant circuit 2, so that the interlaced coupling pair 3 generates the oscillating signal.

The feedback varactor 11 has two connecting ends 111 and 112. The feedback varactor 12 has two connecting ends 121 and 122 respectively. The connecting ends 111 and 112 and the connecting ends 121 and 122 are respectively connected to the NMOS transistors M ₁ and M _{2 .} The 汲 extreme and the source are extreme, and each has a second control terminal 102 sharing a second control voltage V _ctrl2 for synchronous adjustment.

In this embodiment, the NMOS terminal and the source terminal of the two NMOS transistors M ₁ and M ₂ of the interleaved coupling pair 3 are respectively connected back to the varactors 11 and 12, and the capacitances of the varactors 11 and 12 are the same. The specification makes the feedback paths of the left and right sides completely symmetrical, and then connects the respective feedback _varactors 11, 12 to the same group of second control terminals 102, and uses the second control voltage V _{ctrl2 to} perform synchronous adjustment of the output frequency.

In this embodiment, the voltage-controlled oscillating device 100 further includes two sets of buffer amplifiers 41 and 42 respectively connected between the 汲 terminals of the NMOS transistors M ₁ and M ₂ and the respective output terminals 402 and 403. The gate terminal of 41, 42 is connected to the positive bias source 201 of the voltage controlled oscillation device via the inductor module 21.

In this embodiment, the two buffer amplifiers 41 and 42 are coupled to a buffer amplifier positive bias source 401, and the two buffer amplifiers 41 and 42 respectively include a common source transistor M ₃ , M ₄ , an output inductor L _D21 , L _{D22 .} , a base resistor R _B, and an output capacitor C _o1, C _o2, each of the common source stage transistor M _3, M ₄ and the source terminal connected to ground, each of the common source stage transistor M _3, M ₄ the gate terminal provided for receiving the second output of the LC resonant circuit oscillating signal, each of the common source stage transistor M _3, M ₄ the base terminal connected via the base resistor R _B to a base bias V _B, each of the common source stage transistor M _3, M _At the extreme of ₄ , the buffer amplifier positive bias source 401 is connected via the output inductors L _D21 , L _D22 .

In the case of addition of the two feedback varactors 11 and 12, the oscillation signal of the LC resonant circuit 2 outputs Δ f is the frequency adjustment range by Equation 1.

Wherein, L _{D 11} is the equivalent inductance value of the inductance module 21, Δ C _var1 is the equivalent adjustable capacitance value of the capacitance module 22, and Δ C _{var2, 3} are the two sets of feedback _varactors 11, 12, etc. Adjustable capacitance value.

Preferred embodiment according to the present embodiment, the voltage control oscillation means 100 further comprises adding an inductor L _S1 are respectively connected to each of the two NMOS transistors M _1, M source terminal of the inductor L _{S1 2,} L _S2, in, In the case of L _S2 , the oscillation signal output from the inductance-capacitance resonance circuit 2 is as the frequency adjustment range Δ f of Equation 2.

Among them, each parameter can refer to Formula 1, and L _S is the equivalent inductance value of the two sets of inductors L _S1 and L _S2 .

It can be observed from Equation 1 and Equation 2 that the frequency range of the voltage-controlled oscillation device 100 having the two sets of feedback varactors 11, 12 is wider than that of the voltage-controlled oscillator without the feedback of the varactors 11, 12, and In addition, after feedback to the varactors 11, 12, not only can the voltage controlled oscillator be adjusted to adjust the bandwidth, but also the output voltage swing can be increased to improve phase noise.

As is known to us, the phase noise of the voltage controlled oscillator circuit using the CMOS process of the voltage controlled oscillator device 100 is limited by the inductance of the resonant cavity or the quality factor of the variable capacitor (Q factor). In the preferred embodiment, The quality factors of the inductors L _D11 and L _S1 at a frequency of 24 GHz are 18.6 and 34.6, respectively. In addition, the preferred embodiment uses an accumulation mode varactor, and the incremental varactor has a higher capacitance quality. Factors, using a cumulative varactor to achieve a high quality factor cavity, exhibiting low phase noise characteristics; in addition, the voltage controlled oscillating device 100 is fabricated by TSMC 0.18-μm Mixed Signal RF CMOS process technology, and then by actual amount Measure the obtained verification value.

Referring to FIG. 3, taking the voltage-controlled oscillating device not added to the feedback varactors 11, 12 as an example, the output oscillating frequency can only regulate the oscillating frequency by using the first control voltage V _ctrl1 , and the oscillating frequency range is about 20.2 to 23.1 GHz; However, after the feedback containers 11 and 12 are added, the oscillation frequency outputted by the voltage controlled oscillation device 100 can be controlled not only by the first control voltage V _ctrl1 , but also by the second control voltage V _{ctrl2 ,} which can control the output frequency of the oscillation signal. The frequency adjustment range of the voltage controlled oscillation device 100 is increased.

Referring to FIG. 4, comparing the output voltage swing of the voltage-controlled oscillating device 100 of the present invention without adding the varactors 11, 12 and the enthalpy terminals of the feedback varactors 11, 12 is added to the feedback varactors 11, 12 The unmodified varactors 11, 12 have a large voltage swing.

Referring to FIG. 5, comparing the phase noise of the voltage-controlled oscillating device 100 of the present invention without adding the varactors 11, 12 and the feedback varactors 11, 12, the phase of the varactors 11, 12 can be obtained. The noise is -105.8 dBc/Hz at an offset carrier frequency of 1 MHz, and after the feedback varactors 11, 12 are added, the phase noise obtained is -108.1 dBc/Hz, and it is known that the voltage controlled oscillation device 100 of the present invention is added. The feedback of the varactors 11, 12 significantly reduces the phase noise.

In summary, the voltage control oscillating device 100 of the present invention has the effect of increasing the frequency adjustment range of the oscillating signal by providing two sets of feedback varactors 11, 12, and by providing two sets of feedback varactors 11, The amplitude of the output voltage of the voltage controlled oscillation device 100 is increased while the phase noise is reduced, so that the object of the present invention can be achieved.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

[知知]

9. . . Voltage controlled oscillation device

91. . . Inductance and capacitance resonance circuit

911. . . Variable container

92. . . Interlaced pair

93. . . Voltage controlled current source

[This creation]

100. . . Voltage controlled oscillation device

101. . . First control terminal

102. . . Second control terminal

11,12. . . Feedback varactor

111, 112, 121, 122. . . Connection end

2. . . Inductance and capacitance resonance circuit

201. . . Voltage controlled oscillator positive bias source

twenty one. . . Inductor module

211, 212, 402, 403. . . Output

twenty two. . . Capacitor module

3. . . Interlaced pair

41, 42. . . Buffer amplifier

401. . . Buffer amplifier positive bias source

C _o1 , C _o2 . . . Output capacitor

L _D11 , L _D12 . . . inductance

L _D21 , L _D22 . . . Output inductance

L _S1 , L _S2 . . . Inductor

M ₁ , M ₂ . . . Transistor

M ₃ , M ₄ . . . Common source transistor

R _B . . . Base resistance

V _B . . . Base bias

V _buf . . . Buffer amplifier positive bias

V _ctrl1 . . . First control voltage

V _ctrl2 . . . Second control voltage

V _DD . . . Voltage controlled oscillator device is biased

Figure 1 is a circuit diagram showing a conventional voltage controlled oscillation device;

Figure 2 is a circuit diagram showing a preferred embodiment of the voltage controlled oscillation device of the present invention;

3 is a graph illustrating that the voltage controlled oscillation device of the present invention utilizes a first control voltage and a second control voltage to regulate different ranges of oscillation frequencies;

Figure 4 is a graph illustrating the voltage swing of the output voltage of the voltage controlled oscillating device of the present invention without adding the varactor and the return varactor; and

Figure 5 is a graph illustrating the phase noise of the voltage controlled oscillating device of the present invention without the return of the varactor and the addition of the varactor.

100. . . Voltage controlled oscillation device

101. . . First control terminal

102. . . Second control terminal

11,12. . . Feedback varactor

111, 112, 121, 122. . . Connection end

2. . . Inductance and capacitance resonance circuit

201. . . Voltage controlled oscillator positive bias source

twenty one. . . Inductor module

211, 212, 402, 403. . . Output

twenty two. . . Capacitor module

3. . . Interlaced pair

41, 42. . . Buffer amplifier

401. . . Buffer amplifier positive bias source

C _o1 , C _o2 . . . Output capacitor

L _D11 , L _D12 . . . inductance

L _D21 , L _D22 . . . Output inductance

L _S1 , L _S2 . . . Inductor

M ₁ , M ₂ . . . Transistor

M ₃ , M ₄ . . . Common source transistor

R _B . . . Base resistance

V _B . . . Base bias

V _buf . . . Buffer amplifier positive bias

V _ctrl1 . . . First control voltage

V _ctrl2 . . . Second control voltage

V _DD . . . Voltage controlled oscillator device is biased

Claims (4)

A voltage-controlled oscillating device includes: an inductor-capacitor resonant circuit having a first control terminal and two output terminals for receiving a first control voltage, and an inductor module electrically connected to the first control terminal and the two output terminals And a capacitor module, wherein the inductor module and the capacitor module change the frequency of an output of the oscillation signal as the first control voltage changes; an interleaved coupling pair includes two NMOSs electrically connected to the two outputs respectively a transistor, and the gates of each other are cross-connected with the other of the drain electrodes, the absolute value of the negative impedance generated by the interleaved coupling pair is greater than the equivalent resistance value of the inductor-capacitor resonant circuit, so that the interlaced pair generates the oscillation signal; And two sets of feedback varactors respectively have two connection ends, and two connection ends of the two sets of feedback varactors are respectively connected to the 汲 extremes and the source terminals of the NMOS transistors, and the two sets of feedback varactors have common A second control voltage is provided for a second control terminal for synchronous adjustment. The voltage-controlled oscillating device according to claim 1, further comprising two sets of inductors respectively connected to source terminals of the NMOS transistors. The voltage-controlled oscillating device according to claim 1 or 2, further comprising two sets of buffer amplifiers respectively connected between the 汲 terminal of each NMOS transistor and each of the output terminals, and the gate terminals of the buffer amplifiers The positive bias source of the voltage controlled oscillating device is connected via the inductor module. The voltage-controlled oscillating device according to claim 3, wherein each of the buffer amplifiers cooperates with a buffer amplifier positive bias source, and includes a common source stage transistor, an output inductor, a base resistor and an output capacitor. The source terminal of the common source stage transistor is connected to the source, and the gate terminal of the common source stage transistor receives an oscillation signal outputted by the inductor-capacitor resonant circuit, and the base terminal of the common source stage transistor is connected to the base resistor via the base resistor The base bias voltage, the 汲 terminal of the common source stage transistor is connected to the buffer amplifier positive bias source via the output inductor.